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Percutaneous transluminal coronary angioplasty in patients with prior coronary artery bypass grafting
J
THoRAc CARDIOVASC SURG
1987;93:268-75
Percutaneous transluminal coronary angioplasty in patients with prior coronary artery bypass grafting Long-term results In 83 patients with previous coronary artery bypass grafting, 92 percutaneous transluminal coronary angioplasty attempts were done, 33 in a venous bypass graft (success rate 97 %) and 59 in a native coronary artery (success rate 86.4 %). There were no procedural-related deaths and two myocardial infarctions. Forty-six percent of the patients with successful angioplasty after previous bypass grafting remain symptom free after 5 years versus 79 % of the patients without previous bypass grafting (p < 0.001). Long-term success rates for native vessel angioplasty as compared with bypass graft angioplasty are similar. Patients with a short interval between the recurrrnce of angina after bypass, grafting and the angioplasty attempt have a better chance of long-term success. Repeat angiography indicates that a restenosis occurs after angioplasty of a venous graft in 31 % and in the native system in 28.6 % and that signs of progression of coronary artery disease elsewhere are present in 30 %. Of the 83 patients, 11 had reoperation eventually. We conclude that percutaneous transluminal coronary angioplasty after coronary bypass grafting gives less satisfactory results than a primary procedure, that angioplasty provides symptomatic relief in a smaUer number of patients than in those with primary angioplasty, but that symptomatic relief is often sufficient to further postpone or prevent bypass grafting and can be achieved with low mortality and low complication rates.
Sjef M. P. G. Ernst, M.D., Taco A. van der Feltz, M.D., Carl A. P. L. Ascoop, M.D., Egbert T. Bal, M.D., Freddy E. E. Vermeulen, M.D., Paul J. Knaepen, M.D., Leo van Bogerijen, M.D., Eduard J. M. van den Berg, M.D., and H. W. Thijs Plokker, M.D., Ph.D., Nieuwegein, Utrecht. The Netherlands
Although percutaneous transluminal coronary angioplasty (PTCA) is an attractive alternative to reoperation in patients with prior coronary artery bypass grafting (CABG) and severe angina pectoris resulting from stenoses either in the vein graft or in the native coronary arteries,':' the long-term effect of this procedure is not known. This study evaluates this procedure as a longterm effective method of treatment of patients with prior CABG and return of disabling symptoms. From the Departments of Cardiology and Cardiovascular Surgery, St. Antonius Hospital, Nieuwegein, Utrecht, The Netherlands. Supported by the Dutch Heart Foundation. Received for publication Dec. 31, 1985. Accepted for publication March 17, 1986. Address for reprints: Dr. H. W. Thijs Plokker, St. Antonius Hospital, P.O. Box 2500, 3430 EM Nieuwegein, The Netherlands.
268
Patients and methods Among the 1989 patients who hadPTCA in our institution from April 1, 1980, to October 1, 1985, the first 1,352 patients had a follow-up period of at least 6 months. Among these there were 83 patients (66 men and 17 women) who had prior CABG. During this same period 259 patients had coronary reoperation in our institution. Therefore approximately 25% of patients who needed a reoperation were estimated to be managed effectively by balloon angioplasty. The age of these 83 patients varied from 28 to 80 years with a mean of 58.7 ± 7.8 years. All patients had disabling symptoms of angina pectoris and were candidates for a repeat bypass operation. Seventeen percent of the patients were in Canadian Heart Association Class II, 55% were in Class III, and 28% were in Class IV. In 75% of the patients PTCA was done electively. Thirty-five percent
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of the patients had a myocardial infarction in the past. In these 83 patients, 92 angioplasty attempts were made. Thirty-three lesions in a venous bypass graft were attempted and 59 in a native coronary artery. Of the 59 segments in the native system, 18 were in the right coronary artery, 31 were in the left anterior descending artery, and 10 were in the circumflex artery. In 29 cases these were new stenoses or stenoses that had not been of significant importance at the time of CABG (less than 50% luminal diameter obstruction). There were 13 "old" stenoses, because of which a single bypass graft had been placed and had become occluded; there were 13 old stenoses, for which a sequential vein graft had been placed and had become occluded; and there were four old stenoses, for which no bypass graft had been placed either because of a surgical error or because the vessel had been considered too small for grafting at the time of operation ( <1.5 mm). In comparing the groups with PTCA in the native vessel and PTCA in the bypass graft, there were no differences in sex, age, or previous myocardial infarction. However, there were slight differences in symptoms (53% of the patients with bypass graft stenoses had emergency PTCA because of unstable angina versus 25% of the patients with PTCA attempts in the native vessels). Of the 33 graft stenoses, only three were in grafts implanted less than 1 year before, four in grafts' implanted less than 3 years before, two less than 3 years, four less than 4 years, five less than 6 years, six less than 8 years, four less than 10 years, and one more than 10 years before. Three patients had a graft stenosis after two previous bypass procedures, and one patient had a graft stenosis after three previous surgical attempts. Twenty-eight graft stenoses were considered atherosclerotic lesions, all in the body of the vein graft. There were only five stenoses at the distal anastomotic site, which might be considered to be due to either a technical problem or intimal hyperplasia. Primary success was defined as a reduction of diameter stenosis by 20% or more without complications during the procedure, such as death, emergency CABG, or myocardial infarction, and with functional improvement.' Angiographic recurrence was defined as a loss of 50% or more of the initial diameter gain.' All patients were receiving anticoagulants before, during, and after PTCA, but after the procedure they also received either 325 mg of acetylsalicylic acid or 300 mg of dipyridamole per day, and calcium entry blockers. Significance of the difference was assessed by the chi
PTCA in patients with prior CABG
269
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Fig. 1. Actuarial angina-free curves for patients who had a successful percutaneous transluminal coronary angioplasty (PTCA). Solid line. patients without previous coronary artery bypass graft (CABG). Dotted line, patients with previous CABG.
square analysis. Event-free actuarial curves were based op the absence of recurrence of angina pectoris, myocardial infarction, repeat PTCA, CABG, and death. Significance of the difference between acturial curves was assessed by the log-rank or Mantel-Haenszel test. Results There were no procedural-related deaths, and 88% of the procedures were fully uncomplicated. The primary success rate per patient was 91.5% (76/83); the success rate per stenosis was 91.3% (84/92). The success rate in the bypass graft was significantly higher than in the native vessel: 97% (32/33) versus 86.4 (51/59). The success rate for "old" stenoses in the native vessel was 90% and for "new" stenoses, 86% (25/29). One patient had a subendocardial myocardial infarction, and one patient had a transmural myocardial infarction, both shortly after a successful PTCA. Three patients had elective CABG after the PTCA attempt failed. There were no emergency CABG procedures required after unsuccessful PTCA. The stenoses decreased from 81.52% ± 8.75% before PTCA to 19.06% ± 13.69% immediately after PTCA. There were no significant differences in stenosis reduction between graft stenoses and native vessel stenoses. The "age" of the bypass graft did not influence the angiographic result. There were no distal embolizations of bypass graft atheroma during PTCA.
The Journal of Thoracic and Cardiovascular Surgery
2 7 0 Ernst et al.
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Fig. 2. Actuarial angina-free curves for patients who had successful PTCA after previous CABO. Solid line. patients who had successful PTCA of a venous bypass graft. Dotted line. patients who had successful PTCA of a native vessel segment.
Fig. 3. Actuarial angina-free curves for patients who had successful PTCA after previous CABO. Solid line, patients who could be completely revascularized by PTCA. Dotted line. patients who were incompletely revascularized by PTCA.
Long-term clinical results
The completeness of revascularization at the time of PTCA does not influence the results (Fig. 3). Of the patients who could be completely revascularized by PTCA after CABG, 58% were angina free after 5 years, whereas 27.5% were symptom free after incomplete revascularization by PTCA after previous CABO (p = 0.461). The presence of only one severe (not bypassed) stenosis that could be successfullydilated was associated with 73.6% of the patients with previous CABG being asymptomatic after 5 years, whereas of the patients without previous CABG, 81.7% were asymptomatic 5 years after successful PTCA of the only substantial stenosis present (p = 0.170) (Fig. 4). Complete revascularization was considered possible in oIily 66% of the patients with previous CABG versus 79% of the patients without previous CABG. The duration of anginal complaints recurring after CABG and therefore before PTCA also influences the results. When anginal complaints had been present for less than 6 months, the chance of recurrence was much smaller than for the patients who had had angina pectoris for a longer period before PTCA (p = 0.07) (Fig. 5).
The actuarial angina-free curve for those patients who had a successful PTCA is given in Fig. 1. The mean follow-up period was 19.26 ± 10.95 months. After 5 years, 46% of the patients were free of angina pectoris and had had no myocardial infarction. There were-no myocardial infarctions during the period following PTCA after previous CABG. One patient died 3 months after successful PTCA of a bypass graft. No postmortem study was done. In comparing this group of patients with previous CABG with the patients who had PTCA without previous CABG in our institution, we found that 79% of the latter group are symptomless after 5 years versus 46% in the CABG group (p < 0.001). In comparing patients who had a successful PTCA of a bypass graft with those who had a successful PTCA of a native vessel after CABG, there is no statistically significant difference (p = 0.585) between the percentages of patients who are angina free after 5 years, but both groups are relatively small (Fig. 2). If symptoms recur, this happens in the same interval after PTCA for both groups (after bypass graft dilatation, mean 13.85 ± 11.73 months; after native vessel dilatation, mean 12.53 ± 11.74 months. If angina pectoris recurred, there were relatively fewer patients with Canadian Heart Association Class III or IV symptoms in the group of patients with PTCA of the native vessel (38%) than in the group of patients with previous bypass graft dilatation (52%) (p < 0.001).
Long-term angiographic results As is often the case in studies evaluating the angiographic success rate late after PTCA, the recurrence rates are heavily influenced by the definition of recurrence and by the presence or absence of symptoms, an
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PTCA in patients with prior CABG
271
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Fig. 4. Actuarial angina-free curves for patients with only one severe bypassed stenosis, which could be successfully dilated. 'Solid line, patients without previous CABO. Dotted line, patients with previous CABO.
influence that can be eliminated only by doing control angiography in all patients. However, since patients with previous CABG and recurring angina pectoris, for which they have had a repeat angiogram followed by PTCA, already had least three angiographic studies, it is even more likely for the asymptomatic patients in this group to refuse repeat angiography than for the patients who had PTCA without previous CABG. Forty-one of the 83 patients with successful PTCA after previous CABG had a repeat angiogram, that is 49% (as compared with 62% of our patients without previousCABG). Whereas the degree of stenosis immediately after successful PTCA did not differ between the two groups, the mean stenosis at follow-up angiography did differ (37.6% ± 35.32% versus 30.35% ± 29.36% without previousCABG). The mean stenosis in the graft late after PTCA was 42.56% ± 35.44% versus 33.82% ± 35.50% in the native vessel after PTCA following previous CABG. A restenosis occurred in 31% of the patients with PTCA of a graft stenosis versus 28.6% of the patients with PTCA in the native system. In the patients restudied after PTCA following CABG, no less than 30% showed signs of progression elsewherein the coronary arteries or in the bypass grafts (new stenoses >50%). This progression was seen in only 11% of the patients who had PTCA without previous CABG. The left ventricular function improved or remained unchanged in all patients but one with a control
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Fig. 5. Actuarial angina-free curves for patients who had successful PTCA after previous CABO. Solid line, patients who had (recurrence of) anginal complaints for more than 6 months before PTCA.
angiographic study. All 42 patients who refused a control coronary angiogram and 25 patients who had a control coronary angiogram were further treated conservatively. Six patients had a second PTCA (two bypass graft stenoses and four native vessel stenoses). Eight patients had a reoperation (three mainly because of a restenosis in the bypass graft and five because of native vessel disease), and two patients had a second PTCA for a new stenosis elsewhere in the coronary arteries. From the total group of 83 patients who were all candidates for reoperation, 11 patients (13.2%) had reoperation, three because of a failed PTCA attempt and eight because of recurrence of a stenosis. Discussion Although CABG has been proved an excellent method of treatment of obstructive coronary artery disease, and especially an excellent method of symptomatic treatment, angina pectoris recurs or progresses in about 5% of the patients per year,u·6 Therefore many prior bypass patients are likely to have symptoms of ischemia usually related to progression of the disease within the native coronary artery and/or the vein graft. As repeat myocardial revascularization procedures are associated with a higher incidence of complications and less good symptomatic relief,' PTCA has been given a chance to obtain at least symptomatic improvement. Our results indicate that PTCA of a bypass graft can be done with a high success rate, a low complication rate, very low mortality, and few complications, inde-
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2 7 2 Ernst et al.
pendent of the age of the bypass graft. Distal embolization of a coronary artery bypass graft atheroma, which has been described and is believed to be especially possible in "old" grafts, was not encountered by us." Also, the recurrence rate of bypass stenoses does not seem to be as high as previously suggested.l' especially if one takes into account that most of the stenoses in the bypass grafts in our series were in the mid-saphenous vein graft, of which others? reported that patency was unfavorable compared with patency rates for PTCA of distal (vein graft to coronary artery) anastomoses, of which only few were present in our series. PTCA of stenoses already present at the time of operation could be anticipated to yield better primary results than PTCA of new stenoses. However, this was not the case in our group, with the success rate of PTCA for "old" stenoses being even higher than the newly acquired lesions. One might also expect that PTCA of "new" stenoses in the coronary arteries would yield as good a symptomatic effect as in patients without previous CABG if the "new" stenosis is the only cause of ischemia in such patients. However, this does not seem to be the case and can at least partially be explained by a higher incidence of progression of the disease elsewhere in the coronary arteries. Because this is unlikely to be due to the PTCA procedure itself, it could be that new stenoses develop at a higher rate and more diffusely in patients who have had previous CABG than in other coronary patients. This explanation may be emphasized by the fact that the rate of restenosis after successful PTCA in patients with previous CABG is similar to the restenosis rate in such segments in patients without previous CABG. It can be concluded that just as a second surgical myocardial revascularization gives less satisfactory results than a primary operation, PTCA provides symptomatic relief in a smaller number of patients than in those with a primary PTCA. However, symptomatic relief is often sufficient to further postpone or prevent CABG and can be achieved with a low mortality and a low complication rate. REFERENCES Dorros G, Johnson WD, Tector AJ, Schmahl TM, Kalush SL, Janke L. Percutaneous trans luminal coronary angioplasty in patients with prior coronary artery bypass grafting. J THORAC CARDIOVASC SURG 1984;87:17-26. 2 Jones EL, Douglas JS, Gruentzig AR, et al. Percutaneous saphenous vein angioplasty to avoid reoperative bypass surgery. Ann Thorac Surg 1983;36:389-94. 3 Block PL, Cowley MJ, Kaltenbach M, Kent KM, Simpson J. Percutaneous angioplasty of stenoses of bypass
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grafts or of bypass anastomotic sites. Am J Cardiol 1984;53:666-8. Kent K, Bentiroglio LG, Block PC, et al. Percutaneous transluminal coronary angioplasty: report of the National Heart, Lung, and Blood Institute. Am J Cardiol 1982; 49:2011-20. Meier B, King SB, Gruentzig AR, et al. Repeat coronary angioplasty. J Am Coli Cardiol 1984;4:463-6. Campeau L, Lesperance J, Hermann J, Corbara F, Grondin CM, Bourassa MG. Loss of improvement of angina between I and 7 years after aortocoronary bypass surgery: correlation with changes in vein grafts and in coronary arteries. Circulation 1978;60(Pt 2):1 1-5. Loop FD, Cosgrove OM, Kramer JR, et al. Late clinical and arteriographic results in 500 coronary artery reoperations. J THORAC CARDIOVASC SURG 1981;81:675-85. Aueron F, Gruentzig AR. Distal embolization of a coronary bypass graft atheroma during percutaneous transluminal coronary angioplasty. Am J Cardiol 1984;53:9534. Douglas JS Jr, Gruentzig AR, King SB, et al. Percutaneous transluminal coronary angioplasty in patients with prior coronary bypass surgery. J Am Coli Cardiol 1983; 4:745-54.
Manuscript reviewers' comment Several centers have reported their results with percutaneous transluminal coronary angioplasty (PTCA) in the heterogeneous group of patients who experience recurrence of disabling angina pectoris after one or more coronary bypass operations (CABG).'·7 Elective reoperation necessarily expends the supply of conduits and limits future surgical options in a progressivedisease while exposing the patient to an operative mortality three to four times that of a primary CABG. 8. 1I The objectives and limitations of PTCA in this setting are similar to those in patients who have not been treated surgically, but the potential risks and benefits are greater and selection criteria must be more stringent. Early possible outcomes include the following: PTCA success yielding relief of angina without reoperation, PTCA failure resulting in elective or emergency reoperation, and complications that may include embolization of vein graft atheroma into the distal coronary circulation resulting in myocardial infarction. In the event of emergency reoperation, there is a further increased risk of surgical misadventure, a longer time to reperfusion compared to emergency primary operations and therefore more myocardial damage, and a greater likelihood of needing intra-aortic balloon pumping with its attendant complications. Emergency reoperation frequently results in a less complete revascularization than would be achieved in an elective procedure and in most cases mandates the use of venous conduits rather than the preferred internal mammary arteries. Given these considerations, it is imperative that as clear an understanding as possible be obtained of the short- and long-term results of PTCA in these patients.
Volume 93 Number 2 February 1987
Initial results. The high initial success rates reported by Ernst and associatesI (97% for venous grafts and 86% for native coronary arteries) are comparable with those previously reported?" These success rates underscore the fact that patients can be selected for favorable initial outcome. Higher vein graft success rates result from greater ease in reaching the stenosis because of the absence of tortuosity and branch points and less tendency for dissection and occlusion. Ernst and associatesdid not report the PTCA success rate for each native coronary artery, but current technology has improved the previously reduced primary success in right and circumflex coronary lesions.2.3.12 Currently available low profile, high pressure, steerable balloon catheter systems permit successful dilatation of old, fibrotic, and calcified lesions that were not amenable to angioplasty in the past. Although Ernst and associates report that only 66% of patients were completely revascularized, it is clear that symptom relief is the primary goal for therapy in most post-CABG patients, and dilation of only one or two of several stenotic vessels may achieve this result and delay the need for reoperation. Complications. The most common serious complication of PTCA, acute occlusion of the vessel being dilated, occurs in 3% to 5% of patients and results in acute myocardial infarction and/or the need for emergency CABG or emergency repeat PTCA.13 Ernst and associates report two myocardial infarctions (2.4%), no emergency repeat PTCAs, no emergency reoperations, no vein graft atheroemboli, and no deaths in 92 procedures in 83 patients. This very low complication rate, resulting from a combination of careful case selection and good angioplasty skills, would be expected to increase as more patients are treated. In three published reports>' of a total of 342 PTCA procedures in 291 patients, acute myocardial infarction occurred in 10 patients (3.7%), emergency bypass was needed in eight (2.9%), and three patients died (1.1 %). Deaths occurred in patients with multivessel disease and/or extensiveleft ventricular dysfunction. Notably, no deaths have occurred at Emory University Hospital with angioplasty in over 600 elective procedures in patients with prior CABG, a striking contrast to the 3% to 9% reported mortality for coronary reoperation."" The importance of case selection is emphasized by the realization that the ability to salvage myocardium that is acutely ischemic and infarcting because of acute coronary occlusion is limited when emergency reoperation is required. This is due to the technical difficulty of reoperative procedures and the longer time required to expose the involved coronary artery and to reestablish coronary blood flow. Consequently, one can expect a higher risk of PTCA in this setting. This risk is determined by the likelihood of acute coronary occlusion, the amount of jeopardized myocardium, residual left ventricular function, and collateral flow, the last item being difficult to estimate and unreliable if systemic hypotension occurs. The recently improved ability to place perfusion catheters in the distal coronary artery to temporarily reinstitute coronary flow permits a degree of stabilization and avoidance of myocardial injury in many patients and rescue of others in whom acute occlusion would produce cardiogenic shock." Unfortunately,
PTCA in patients with prior CABG
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the ability to place these "bailout" catheters is not predictable and their efficacy is reduced if systemic hypotension occurs. Intra-aortic balloon pumping, used routinely in our experience when hemodynamic instability occurs after PTCA, is of substantial benefit but may be inadequate in severely compromised patients. Therefore, before selecting PTCA in a patient who has had a prior operation, one must estimate the likely consequences of acute occlusion while keeping in mind the reduced opportunities for surgical rescue and myocardial salvage if emergency reoperation is required. Embolization of vein graft atheroma, described initially with reoperations," was not observed by Ernst and associates in 33 vein graft PTCA procedures nor by Douglas,' Dorros," Corbelli,' in a total of 141 PTCAs but has occurred in 3% of 235 vein graft angioplasty attempts in our subsequent experience at Emory University Hospital." Embolization is more likely with PTCA in proximal and mid-vein graft stenosis when the grafts have been in place for over 3 years and when stenoses are eccentric, shaggy, large, or multiple. Fortunately, the majority of vein graft atheroemboli in our experience have been small because of the selection of discrete, smooth stenoses for PTCA. The ability for successful surgical intervention in vein graft atheroemboli is limited by fragmentation of the atheroma producing multiple occlusions at the level of the microcirculation. Restenosis. Ernst and associates report that restenosis occurred in 28.6% of native coronary artery lesions and in 31% of vein grafts. As in our experience,' approximately half of the native coronary artery lesions were present at the time of CABG. Unfortunately, the number of patients undergoing late recatheterization was small. Further studies in patients with prior CABG may show a lower native coronary artery restenosis rate compared to that of patients undergoing a primary PTCA, because a larger number of patients will have chronic stenoses that are less likely to recur. Results in vein grafts reported by Ernst and associates are at variance with our experience, which indicates a higher restenosis rate in the proximal and midportions of vein grafts (exceeding 50%) as compared to the junction of the vein graft and coronary artery (the distal anastomosis), where less than 20% of patients undergoing recatheterization have restenosis."!' Ernst and associates do not report the number of vein grafts restudied. However, if the restudy rate of vein grafts was similar to the overall rate of 49%, 17 patients would have undergone recatheterization and this small sample size may contribute to these different results. In addition, it was not stated whether the denominator used in the calculation of restenosis rates was the number of patients catheterized or the total number in the group. The latter method would give a falsely low estimate of the acutal restenosis rate determined if the entire group was restudied. Very favorable long-term results with PTCA at the distal anastomosis have led us to recatheterize most patients with recurrence of angina postoperatively. The less favorable longterm results with PTCA in other vein graft sites have engendered a more conservative approach and selection of only the more ideal lesions for PTCA.
2 7 4 Ernst et al.
Long-term clinical results. Consequences of restenosis at the angioplasty site (and progression of disease in native coronary arteries and vein grafts) include recurrence of angina, myocardial infarction, and sudden death. Ernst and associates report that a mean follow-up of 19.26 months, no myocardial infarctions were observed, one patient had died suddenly, 11 patients (13%) had required reoperation, and the 5 year actuarial projection indicated 46% of patients were asymptomatic. Because the longest follow-up was 5.5 years, the number of patients actually followed up for 5 years was small. The projected symptomatic results with PTCA, however, appear similar to the 5.5 year follow-up data of Loop and Cosgrove" for reoperative CABG; they reported that 53% of patients were asymptomatic but 12% of the surgical patients had died during this follow-up period. Results of any revascularization procedure are limited by the progressive nature of the disease. Many post-CABG patients in our experience have had more than one PTCA procedure over the years as new stenoses have developed. This ability to achieve effective revascularization while avoiding multiple operations is a significant benefit. Implications of this study. The report by Ernst and associates I parallels previous studies indicating that in carefully selected post-CABG patients, PTCA can be performed with satisfactory safety and good long-term results. Usefulness of this study to make clinical decisions is limited by the lack of guidelines for patient selection for PTCA and by the low restudy rate. Selection of post-CABG patients for PTCA. PTCA should be considered in post-CABG patients when symptoms are disabling and angiographically suitable lesions are presentin the native coronary arteries, vein grafts (distal anastomosis better than midportion or proximal lesions), or internal mammary artery anastomoses. PTCA should be avoided if ( I) acute occlusion of the vessel or vessels dilated would produce cardiogenic shock, (2) the vessel to be dilated is of major importance and intra-aortic balloon pumping is not feasible because of iliac disease or if venous conduits are not readily available, or (3) if multiple or large, irregular vein graft lesions are present suggesting a high risk of distal embolization.
John S. Douglas, Jr., M.D. Spencer B. King Ill, M.D. Gary S. Roubin, M.B., Ph.D. Andreas Gruentzig Cardiovascular Center Departments of Medicine and Radiology Emory University School of Medicine Atlanta, Ga. 30322 REFERENCES 1. Ernst SMPG, van der Feltz TA, Ascoop CAPL, et al. Percutaneous transluminal coronary angioplasty in patients with prior coronary artery bypass grafting: longterm results. J THORAC CARDIOVASC SURG 1987;93:26875. 2. Douglas JS, Gruentzig AR, King SB, et al. Percutaneous transluminal coronary angioplasty in patients with prior
The Journal of Thoracic and Cardiovascular Surgery
coronary bypass surgery. J Am Coli Cardiol 1983;2:74554. 3. Corbelli J, Franco I, Hollman J, Simpfendorfer C, Galan K. Percutaneous transluminal coronary angioplasty after previous coronary artery bypass surgery. Am J Cardiol 1985;56:398-403. 4. Dorros G, Johnson WD, Tector AJ, Schmahl TM, Kalush SL, Janke L. Percutaneous transluminal coronary angioplasty in patients with prior coronary artery bypass grafting. J THORAC CARDIOVASC SURG 1984;87:17-26. 5. Reeder GS, Bresnahan JF, Holmes DR, et al. Angioplasty for aortocoronary bypass graft stenosis. Mayo Clin Proc 1986;61:14-9. 6. Block PC, Cowley MJ, Kaltenbach M, Kent KM, Simpson J. Percutaneous angioplasty of stenoses of bypass grafts or of bypass graft anastomotic sites. Am J Cardiol 1984;53:666-8. 7. Zaidi AR, Hollman JL. Percutaneous angioplasty of internal mammary artery graft stenosis: case report and discussion. Cathet Cardiovasc Diagn 1985;11:603-8. 8. Lytle BW, Loop FD, Cosgrove DM, et al. Fifteen hundred coronary reoperations: results and determinants of early and late survival. J Am Coli Cardiol 1986; 7:31A. 9. Hall RB, Elayda MA, Gray AG, Cooley DA. Reoperation for coronary artery disease. J Am Coli Cardiol 1986;7:32A. 10. Brenowitz J, Dorros G, Schley L, Johnson WD. Coronary artery bypass graft surgery for the third time or more: the results of 90 consecutive operations. J Am Coli Cardiol 1986;7:31A. 11. Kirklin JW, Barratt-Boyes BG. Cardiac surgery: morphology, diagnostic criteria, natural history, techniques, results and indications. New York: John Wiley and Sons, 1986;256. 12. Anderson HV, Leimgruber PP, Roubin GS, Douglas JS Jr, King SB III, Gruentzig AR. Primary angiographic success rates of percutaneous transluminal coronary angioplasty. Am J Cardiol 1985;56:712-7; 13. Bredlau CE, Roubin GS, Leimgruber PP, Douglas JS Jr, King SB III, Gruentzig AR. In-hospital morbidity and mortality in patients undergoing elective coronary angioplasty. Circulation 1985;72:1044-52. 14. Hinohara T, Simpson JB, Phillips HR, et al. Transluminal catheter reperfusion: A new technique to reestablish blood flow after coronary occlusion during percutaneous transluminal coronary angioplasty. Am J Cardiol 1986; 57:684-6. 15. Keon WJ, Heggtveit HA, Leduc J. Perioperative myocardial infarction caused by atheroembolism. J THORAe CARDIOVASC SURG 1982;84:849-55. 16. Douglas J, King S, Robinson K, Schlumpf M. Percutaneous transluminal angioplasty in aortocoronary venous graft stenosis: immediate results and complications. Circulation 1986;74(Pt 2):11363. 17. Douglas J, King S, Roubin G, Schlumpf M. Percutaneous angioplasty of venous aortocoronary graft stenoses: late
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angiographic and clinical outcome. Circulation 1986; 74(Pt 2):I1281. 18. Loop FD, Cosgrove DM. Repeat coronary bypass surgery: selection of cases, surgical risks, and long-term outlook. Mod Cone Cardiovasc Dis 1986;55:31-6.
Response We are pleased that our manuscript is being enhanced by the discussion of our colleagues from Emory University. However, among their comments are two points that perhaps need further clarification. With regard to restenosis rates, we agree that the percentage of patients being restudied angiographically (49%) is not large, but it is much larger than in any other report on PTCA in this subgroup of patients. Such patients are more likely to refuse control angiography than are primary PTCA candidates. The denominator used in the calculation of restenosis rates is obviously the number of patients having a repeat angiographic study. Therefore, it is more likely that we encountered a falsely high estimate of the actual restenosis rate than a falsely low one.
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We disagree with Douglas and associates about the lack of implications of our study for clinical decision making. The definition of angiographically suitable lesions will always remain a point of discussion. However, we have demonstrated that middle or proximal vein graft lesions can also be safely dilated with better results than those reported elsewhere in the literature. We agree that PTCA of multiple, very large, or highly irregular graft lesions should be avoided, but this is also true of lesions in the native coronary system. Therefore, we do not believe this warrants new guidelines. We cannot understand why one should avoid PTCA in vessels in which occlusion might produce cardiogenic shock. Instead, we base our decisions on angiographic suitability rather than myocardial areas at risk. Our good success with PTCA of proximal stenoses in large jump or snake grafts (not specifically mentioned) underlines this. H. W Thijs Plokker, M.D., Ph.D. Sjef M. P. G. Ernst, M.D. Nieuwegein, Utrecht, The Netherlands
Bound volumes available to subscribers Bound volumes of THE JOURNAL OF THORACIC AND CARDIOVASCULAR SURGERY are available to subscribers (only) for the 1987 issues from the Publisher, at a costof $49.00 ($66.00 international) for Vol. 93 (January-June) and Vol. 94 (July-December). Shipping charges are included. Each bound volume contains a subject and author index and all advertising is removed. Copies are shipped within 60 days after publication of the last issue of the volume. The binding is durable buckram with the JOURNAL name, volume number, and year stamped ingold on thespine. Payment must accompany all orders. ContactThe C. V. Mosby Company, Circulation Department, 11830 Westline Industrial Drive, St. Louis, Missouri 63146, USA; phone (800) 325-4177, ext. 351. Subscriptions must be in force to qualify. Bound volumes are not available in place of a regular JOURNAL subscription.
THoRAc CARDIOVASC SURG
1987;93:268-75
Percutaneous transluminal coronary angioplasty in patients with prior coronary artery bypass grafting Long-term results In 83 patients with previous coronary artery bypass grafting, 92 percutaneous transluminal coronary angioplasty attempts were done, 33 in a venous bypass graft (success rate 97 %) and 59 in a native coronary artery (success rate 86.4 %). There were no procedural-related deaths and two myocardial infarctions. Forty-six percent of the patients with successful angioplasty after previous bypass grafting remain symptom free after 5 years versus 79 % of the patients without previous bypass grafting (p < 0.001). Long-term success rates for native vessel angioplasty as compared with bypass graft angioplasty are similar. Patients with a short interval between the recurrrnce of angina after bypass, grafting and the angioplasty attempt have a better chance of long-term success. Repeat angiography indicates that a restenosis occurs after angioplasty of a venous graft in 31 % and in the native system in 28.6 % and that signs of progression of coronary artery disease elsewhere are present in 30 %. Of the 83 patients, 11 had reoperation eventually. We conclude that percutaneous transluminal coronary angioplasty after coronary bypass grafting gives less satisfactory results than a primary procedure, that angioplasty provides symptomatic relief in a smaUer number of patients than in those with primary angioplasty, but that symptomatic relief is often sufficient to further postpone or prevent bypass grafting and can be achieved with low mortality and low complication rates.
Sjef M. P. G. Ernst, M.D., Taco A. van der Feltz, M.D., Carl A. P. L. Ascoop, M.D., Egbert T. Bal, M.D., Freddy E. E. Vermeulen, M.D., Paul J. Knaepen, M.D., Leo van Bogerijen, M.D., Eduard J. M. van den Berg, M.D., and H. W. Thijs Plokker, M.D., Ph.D., Nieuwegein, Utrecht. The Netherlands
Although percutaneous transluminal coronary angioplasty (PTCA) is an attractive alternative to reoperation in patients with prior coronary artery bypass grafting (CABG) and severe angina pectoris resulting from stenoses either in the vein graft or in the native coronary arteries,':' the long-term effect of this procedure is not known. This study evaluates this procedure as a longterm effective method of treatment of patients with prior CABG and return of disabling symptoms. From the Departments of Cardiology and Cardiovascular Surgery, St. Antonius Hospital, Nieuwegein, Utrecht, The Netherlands. Supported by the Dutch Heart Foundation. Received for publication Dec. 31, 1985. Accepted for publication March 17, 1986. Address for reprints: Dr. H. W. Thijs Plokker, St. Antonius Hospital, P.O. Box 2500, 3430 EM Nieuwegein, The Netherlands.
268
Patients and methods Among the 1989 patients who hadPTCA in our institution from April 1, 1980, to October 1, 1985, the first 1,352 patients had a follow-up period of at least 6 months. Among these there were 83 patients (66 men and 17 women) who had prior CABG. During this same period 259 patients had coronary reoperation in our institution. Therefore approximately 25% of patients who needed a reoperation were estimated to be managed effectively by balloon angioplasty. The age of these 83 patients varied from 28 to 80 years with a mean of 58.7 ± 7.8 years. All patients had disabling symptoms of angina pectoris and were candidates for a repeat bypass operation. Seventeen percent of the patients were in Canadian Heart Association Class II, 55% were in Class III, and 28% were in Class IV. In 75% of the patients PTCA was done electively. Thirty-five percent
Volume 93 Number 2 February 1987
of the patients had a myocardial infarction in the past. In these 83 patients, 92 angioplasty attempts were made. Thirty-three lesions in a venous bypass graft were attempted and 59 in a native coronary artery. Of the 59 segments in the native system, 18 were in the right coronary artery, 31 were in the left anterior descending artery, and 10 were in the circumflex artery. In 29 cases these were new stenoses or stenoses that had not been of significant importance at the time of CABG (less than 50% luminal diameter obstruction). There were 13 "old" stenoses, because of which a single bypass graft had been placed and had become occluded; there were 13 old stenoses, for which a sequential vein graft had been placed and had become occluded; and there were four old stenoses, for which no bypass graft had been placed either because of a surgical error or because the vessel had been considered too small for grafting at the time of operation ( <1.5 mm). In comparing the groups with PTCA in the native vessel and PTCA in the bypass graft, there were no differences in sex, age, or previous myocardial infarction. However, there were slight differences in symptoms (53% of the patients with bypass graft stenoses had emergency PTCA because of unstable angina versus 25% of the patients with PTCA attempts in the native vessels). Of the 33 graft stenoses, only three were in grafts implanted less than 1 year before, four in grafts' implanted less than 3 years before, two less than 3 years, four less than 4 years, five less than 6 years, six less than 8 years, four less than 10 years, and one more than 10 years before. Three patients had a graft stenosis after two previous bypass procedures, and one patient had a graft stenosis after three previous surgical attempts. Twenty-eight graft stenoses were considered atherosclerotic lesions, all in the body of the vein graft. There were only five stenoses at the distal anastomotic site, which might be considered to be due to either a technical problem or intimal hyperplasia. Primary success was defined as a reduction of diameter stenosis by 20% or more without complications during the procedure, such as death, emergency CABG, or myocardial infarction, and with functional improvement.' Angiographic recurrence was defined as a loss of 50% or more of the initial diameter gain.' All patients were receiving anticoagulants before, during, and after PTCA, but after the procedure they also received either 325 mg of acetylsalicylic acid or 300 mg of dipyridamole per day, and calcium entry blockers. Significance of the difference was assessed by the chi
PTCA in patients with prior CABG
269
%
100
79,2
......•......~
. ................................
'.
46,6
6
12 18 24 30 36 42 48 54 60
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Fig. 1. Actuarial angina-free curves for patients who had a successful percutaneous transluminal coronary angioplasty (PTCA). Solid line. patients without previous coronary artery bypass graft (CABG). Dotted line, patients with previous CABG.
square analysis. Event-free actuarial curves were based op the absence of recurrence of angina pectoris, myocardial infarction, repeat PTCA, CABG, and death. Significance of the difference between acturial curves was assessed by the log-rank or Mantel-Haenszel test. Results There were no procedural-related deaths, and 88% of the procedures were fully uncomplicated. The primary success rate per patient was 91.5% (76/83); the success rate per stenosis was 91.3% (84/92). The success rate in the bypass graft was significantly higher than in the native vessel: 97% (32/33) versus 86.4 (51/59). The success rate for "old" stenoses in the native vessel was 90% and for "new" stenoses, 86% (25/29). One patient had a subendocardial myocardial infarction, and one patient had a transmural myocardial infarction, both shortly after a successful PTCA. Three patients had elective CABG after the PTCA attempt failed. There were no emergency CABG procedures required after unsuccessful PTCA. The stenoses decreased from 81.52% ± 8.75% before PTCA to 19.06% ± 13.69% immediately after PTCA. There were no significant differences in stenosis reduction between graft stenoses and native vessel stenoses. The "age" of the bypass graft did not influence the angiographic result. There were no distal embolizations of bypass graft atheroma during PTCA.
The Journal of Thoracic and Cardiovascular Surgery
2 7 0 Ernst et al.
57,6
'.'.
........... "
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- ------
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.
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12 18 24 30 36 42 48 54 60
\
,
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.
12 18 24 30 36 42 48 54 60
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months
Fig. 2. Actuarial angina-free curves for patients who had successful PTCA after previous CABO. Solid line. patients who had successful PTCA of a venous bypass graft. Dotted line. patients who had successful PTCA of a native vessel segment.
Fig. 3. Actuarial angina-free curves for patients who had successful PTCA after previous CABO. Solid line, patients who could be completely revascularized by PTCA. Dotted line. patients who were incompletely revascularized by PTCA.
Long-term clinical results
The completeness of revascularization at the time of PTCA does not influence the results (Fig. 3). Of the patients who could be completely revascularized by PTCA after CABG, 58% were angina free after 5 years, whereas 27.5% were symptom free after incomplete revascularization by PTCA after previous CABO (p = 0.461). The presence of only one severe (not bypassed) stenosis that could be successfullydilated was associated with 73.6% of the patients with previous CABG being asymptomatic after 5 years, whereas of the patients without previous CABG, 81.7% were asymptomatic 5 years after successful PTCA of the only substantial stenosis present (p = 0.170) (Fig. 4). Complete revascularization was considered possible in oIily 66% of the patients with previous CABG versus 79% of the patients without previous CABG. The duration of anginal complaints recurring after CABG and therefore before PTCA also influences the results. When anginal complaints had been present for less than 6 months, the chance of recurrence was much smaller than for the patients who had had angina pectoris for a longer period before PTCA (p = 0.07) (Fig. 5).
The actuarial angina-free curve for those patients who had a successful PTCA is given in Fig. 1. The mean follow-up period was 19.26 ± 10.95 months. After 5 years, 46% of the patients were free of angina pectoris and had had no myocardial infarction. There were-no myocardial infarctions during the period following PTCA after previous CABG. One patient died 3 months after successful PTCA of a bypass graft. No postmortem study was done. In comparing this group of patients with previous CABG with the patients who had PTCA without previous CABG in our institution, we found that 79% of the latter group are symptomless after 5 years versus 46% in the CABG group (p < 0.001). In comparing patients who had a successful PTCA of a bypass graft with those who had a successful PTCA of a native vessel after CABG, there is no statistically significant difference (p = 0.585) between the percentages of patients who are angina free after 5 years, but both groups are relatively small (Fig. 2). If symptoms recur, this happens in the same interval after PTCA for both groups (after bypass graft dilatation, mean 13.85 ± 11.73 months; after native vessel dilatation, mean 12.53 ± 11.74 months. If angina pectoris recurred, there were relatively fewer patients with Canadian Heart Association Class III or IV symptoms in the group of patients with PTCA of the native vessel (38%) than in the group of patients with previous bypass graft dilatation (52%) (p < 0.001).
Long-term angiographic results As is often the case in studies evaluating the angiographic success rate late after PTCA, the recurrence rates are heavily influenced by the definition of recurrence and by the presence or absence of symptoms, an
Volume 93 Number 2 February 1987
PTCA in patients with prior CABG
271
100"10
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Fig. 4. Actuarial angina-free curves for patients with only one severe bypassed stenosis, which could be successfully dilated. 'Solid line, patients without previous CABO. Dotted line, patients with previous CABO.
influence that can be eliminated only by doing control angiography in all patients. However, since patients with previous CABG and recurring angina pectoris, for which they have had a repeat angiogram followed by PTCA, already had least three angiographic studies, it is even more likely for the asymptomatic patients in this group to refuse repeat angiography than for the patients who had PTCA without previous CABG. Forty-one of the 83 patients with successful PTCA after previous CABG had a repeat angiogram, that is 49% (as compared with 62% of our patients without previousCABG). Whereas the degree of stenosis immediately after successful PTCA did not differ between the two groups, the mean stenosis at follow-up angiography did differ (37.6% ± 35.32% versus 30.35% ± 29.36% without previousCABG). The mean stenosis in the graft late after PTCA was 42.56% ± 35.44% versus 33.82% ± 35.50% in the native vessel after PTCA following previous CABG. A restenosis occurred in 31% of the patients with PTCA of a graft stenosis versus 28.6% of the patients with PTCA in the native system. In the patients restudied after PTCA following CABG, no less than 30% showed signs of progression elsewherein the coronary arteries or in the bypass grafts (new stenoses >50%). This progression was seen in only 11% of the patients who had PTCA without previous CABG. The left ventricular function improved or remained unchanged in all patients but one with a control
""
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.................................
12 18 24 30 36 42 48 54 60 months
Fig. 5. Actuarial angina-free curves for patients who had successful PTCA after previous CABO. Solid line, patients who had (recurrence of) anginal complaints for more than 6 months before PTCA.
angiographic study. All 42 patients who refused a control coronary angiogram and 25 patients who had a control coronary angiogram were further treated conservatively. Six patients had a second PTCA (two bypass graft stenoses and four native vessel stenoses). Eight patients had a reoperation (three mainly because of a restenosis in the bypass graft and five because of native vessel disease), and two patients had a second PTCA for a new stenosis elsewhere in the coronary arteries. From the total group of 83 patients who were all candidates for reoperation, 11 patients (13.2%) had reoperation, three because of a failed PTCA attempt and eight because of recurrence of a stenosis. Discussion Although CABG has been proved an excellent method of treatment of obstructive coronary artery disease, and especially an excellent method of symptomatic treatment, angina pectoris recurs or progresses in about 5% of the patients per year,u·6 Therefore many prior bypass patients are likely to have symptoms of ischemia usually related to progression of the disease within the native coronary artery and/or the vein graft. As repeat myocardial revascularization procedures are associated with a higher incidence of complications and less good symptomatic relief,' PTCA has been given a chance to obtain at least symptomatic improvement. Our results indicate that PTCA of a bypass graft can be done with a high success rate, a low complication rate, very low mortality, and few complications, inde-
The Journal of Thoracic and Cardiovascular Surgery
2 7 2 Ernst et al.
pendent of the age of the bypass graft. Distal embolization of a coronary artery bypass graft atheroma, which has been described and is believed to be especially possible in "old" grafts, was not encountered by us." Also, the recurrence rate of bypass stenoses does not seem to be as high as previously suggested.l' especially if one takes into account that most of the stenoses in the bypass grafts in our series were in the mid-saphenous vein graft, of which others? reported that patency was unfavorable compared with patency rates for PTCA of distal (vein graft to coronary artery) anastomoses, of which only few were present in our series. PTCA of stenoses already present at the time of operation could be anticipated to yield better primary results than PTCA of new stenoses. However, this was not the case in our group, with the success rate of PTCA for "old" stenoses being even higher than the newly acquired lesions. One might also expect that PTCA of "new" stenoses in the coronary arteries would yield as good a symptomatic effect as in patients without previous CABG if the "new" stenosis is the only cause of ischemia in such patients. However, this does not seem to be the case and can at least partially be explained by a higher incidence of progression of the disease elsewhere in the coronary arteries. Because this is unlikely to be due to the PTCA procedure itself, it could be that new stenoses develop at a higher rate and more diffusely in patients who have had previous CABG than in other coronary patients. This explanation may be emphasized by the fact that the rate of restenosis after successful PTCA in patients with previous CABG is similar to the restenosis rate in such segments in patients without previous CABG. It can be concluded that just as a second surgical myocardial revascularization gives less satisfactory results than a primary operation, PTCA provides symptomatic relief in a smaller number of patients than in those with a primary PTCA. However, symptomatic relief is often sufficient to further postpone or prevent CABG and can be achieved with a low mortality and a low complication rate. REFERENCES Dorros G, Johnson WD, Tector AJ, Schmahl TM, Kalush SL, Janke L. Percutaneous trans luminal coronary angioplasty in patients with prior coronary artery bypass grafting. J THORAC CARDIOVASC SURG 1984;87:17-26. 2 Jones EL, Douglas JS, Gruentzig AR, et al. Percutaneous saphenous vein angioplasty to avoid reoperative bypass surgery. Ann Thorac Surg 1983;36:389-94. 3 Block PL, Cowley MJ, Kaltenbach M, Kent KM, Simpson J. Percutaneous angioplasty of stenoses of bypass
4
5 6
7
8
9
grafts or of bypass anastomotic sites. Am J Cardiol 1984;53:666-8. Kent K, Bentiroglio LG, Block PC, et al. Percutaneous transluminal coronary angioplasty: report of the National Heart, Lung, and Blood Institute. Am J Cardiol 1982; 49:2011-20. Meier B, King SB, Gruentzig AR, et al. Repeat coronary angioplasty. J Am Coli Cardiol 1984;4:463-6. Campeau L, Lesperance J, Hermann J, Corbara F, Grondin CM, Bourassa MG. Loss of improvement of angina between I and 7 years after aortocoronary bypass surgery: correlation with changes in vein grafts and in coronary arteries. Circulation 1978;60(Pt 2):1 1-5. Loop FD, Cosgrove OM, Kramer JR, et al. Late clinical and arteriographic results in 500 coronary artery reoperations. J THORAC CARDIOVASC SURG 1981;81:675-85. Aueron F, Gruentzig AR. Distal embolization of a coronary bypass graft atheroma during percutaneous transluminal coronary angioplasty. Am J Cardiol 1984;53:9534. Douglas JS Jr, Gruentzig AR, King SB, et al. Percutaneous transluminal coronary angioplasty in patients with prior coronary bypass surgery. J Am Coli Cardiol 1983; 4:745-54.
Manuscript reviewers' comment Several centers have reported their results with percutaneous transluminal coronary angioplasty (PTCA) in the heterogeneous group of patients who experience recurrence of disabling angina pectoris after one or more coronary bypass operations (CABG).'·7 Elective reoperation necessarily expends the supply of conduits and limits future surgical options in a progressivedisease while exposing the patient to an operative mortality three to four times that of a primary CABG. 8. 1I The objectives and limitations of PTCA in this setting are similar to those in patients who have not been treated surgically, but the potential risks and benefits are greater and selection criteria must be more stringent. Early possible outcomes include the following: PTCA success yielding relief of angina without reoperation, PTCA failure resulting in elective or emergency reoperation, and complications that may include embolization of vein graft atheroma into the distal coronary circulation resulting in myocardial infarction. In the event of emergency reoperation, there is a further increased risk of surgical misadventure, a longer time to reperfusion compared to emergency primary operations and therefore more myocardial damage, and a greater likelihood of needing intra-aortic balloon pumping with its attendant complications. Emergency reoperation frequently results in a less complete revascularization than would be achieved in an elective procedure and in most cases mandates the use of venous conduits rather than the preferred internal mammary arteries. Given these considerations, it is imperative that as clear an understanding as possible be obtained of the short- and long-term results of PTCA in these patients.
Volume 93 Number 2 February 1987
Initial results. The high initial success rates reported by Ernst and associatesI (97% for venous grafts and 86% for native coronary arteries) are comparable with those previously reported?" These success rates underscore the fact that patients can be selected for favorable initial outcome. Higher vein graft success rates result from greater ease in reaching the stenosis because of the absence of tortuosity and branch points and less tendency for dissection and occlusion. Ernst and associatesdid not report the PTCA success rate for each native coronary artery, but current technology has improved the previously reduced primary success in right and circumflex coronary lesions.2.3.12 Currently available low profile, high pressure, steerable balloon catheter systems permit successful dilatation of old, fibrotic, and calcified lesions that were not amenable to angioplasty in the past. Although Ernst and associates report that only 66% of patients were completely revascularized, it is clear that symptom relief is the primary goal for therapy in most post-CABG patients, and dilation of only one or two of several stenotic vessels may achieve this result and delay the need for reoperation. Complications. The most common serious complication of PTCA, acute occlusion of the vessel being dilated, occurs in 3% to 5% of patients and results in acute myocardial infarction and/or the need for emergency CABG or emergency repeat PTCA.13 Ernst and associates report two myocardial infarctions (2.4%), no emergency repeat PTCAs, no emergency reoperations, no vein graft atheroemboli, and no deaths in 92 procedures in 83 patients. This very low complication rate, resulting from a combination of careful case selection and good angioplasty skills, would be expected to increase as more patients are treated. In three published reports>' of a total of 342 PTCA procedures in 291 patients, acute myocardial infarction occurred in 10 patients (3.7%), emergency bypass was needed in eight (2.9%), and three patients died (1.1 %). Deaths occurred in patients with multivessel disease and/or extensiveleft ventricular dysfunction. Notably, no deaths have occurred at Emory University Hospital with angioplasty in over 600 elective procedures in patients with prior CABG, a striking contrast to the 3% to 9% reported mortality for coronary reoperation."" The importance of case selection is emphasized by the realization that the ability to salvage myocardium that is acutely ischemic and infarcting because of acute coronary occlusion is limited when emergency reoperation is required. This is due to the technical difficulty of reoperative procedures and the longer time required to expose the involved coronary artery and to reestablish coronary blood flow. Consequently, one can expect a higher risk of PTCA in this setting. This risk is determined by the likelihood of acute coronary occlusion, the amount of jeopardized myocardium, residual left ventricular function, and collateral flow, the last item being difficult to estimate and unreliable if systemic hypotension occurs. The recently improved ability to place perfusion catheters in the distal coronary artery to temporarily reinstitute coronary flow permits a degree of stabilization and avoidance of myocardial injury in many patients and rescue of others in whom acute occlusion would produce cardiogenic shock." Unfortunately,
PTCA in patients with prior CABG
273
the ability to place these "bailout" catheters is not predictable and their efficacy is reduced if systemic hypotension occurs. Intra-aortic balloon pumping, used routinely in our experience when hemodynamic instability occurs after PTCA, is of substantial benefit but may be inadequate in severely compromised patients. Therefore, before selecting PTCA in a patient who has had a prior operation, one must estimate the likely consequences of acute occlusion while keeping in mind the reduced opportunities for surgical rescue and myocardial salvage if emergency reoperation is required. Embolization of vein graft atheroma, described initially with reoperations," was not observed by Ernst and associates in 33 vein graft PTCA procedures nor by Douglas,' Dorros," Corbelli,' in a total of 141 PTCAs but has occurred in 3% of 235 vein graft angioplasty attempts in our subsequent experience at Emory University Hospital." Embolization is more likely with PTCA in proximal and mid-vein graft stenosis when the grafts have been in place for over 3 years and when stenoses are eccentric, shaggy, large, or multiple. Fortunately, the majority of vein graft atheroemboli in our experience have been small because of the selection of discrete, smooth stenoses for PTCA. The ability for successful surgical intervention in vein graft atheroemboli is limited by fragmentation of the atheroma producing multiple occlusions at the level of the microcirculation. Restenosis. Ernst and associates report that restenosis occurred in 28.6% of native coronary artery lesions and in 31% of vein grafts. As in our experience,' approximately half of the native coronary artery lesions were present at the time of CABG. Unfortunately, the number of patients undergoing late recatheterization was small. Further studies in patients with prior CABG may show a lower native coronary artery restenosis rate compared to that of patients undergoing a primary PTCA, because a larger number of patients will have chronic stenoses that are less likely to recur. Results in vein grafts reported by Ernst and associates are at variance with our experience, which indicates a higher restenosis rate in the proximal and midportions of vein grafts (exceeding 50%) as compared to the junction of the vein graft and coronary artery (the distal anastomosis), where less than 20% of patients undergoing recatheterization have restenosis."!' Ernst and associates do not report the number of vein grafts restudied. However, if the restudy rate of vein grafts was similar to the overall rate of 49%, 17 patients would have undergone recatheterization and this small sample size may contribute to these different results. In addition, it was not stated whether the denominator used in the calculation of restenosis rates was the number of patients catheterized or the total number in the group. The latter method would give a falsely low estimate of the acutal restenosis rate determined if the entire group was restudied. Very favorable long-term results with PTCA at the distal anastomosis have led us to recatheterize most patients with recurrence of angina postoperatively. The less favorable longterm results with PTCA in other vein graft sites have engendered a more conservative approach and selection of only the more ideal lesions for PTCA.
2 7 4 Ernst et al.
Long-term clinical results. Consequences of restenosis at the angioplasty site (and progression of disease in native coronary arteries and vein grafts) include recurrence of angina, myocardial infarction, and sudden death. Ernst and associates report that a mean follow-up of 19.26 months, no myocardial infarctions were observed, one patient had died suddenly, 11 patients (13%) had required reoperation, and the 5 year actuarial projection indicated 46% of patients were asymptomatic. Because the longest follow-up was 5.5 years, the number of patients actually followed up for 5 years was small. The projected symptomatic results with PTCA, however, appear similar to the 5.5 year follow-up data of Loop and Cosgrove" for reoperative CABG; they reported that 53% of patients were asymptomatic but 12% of the surgical patients had died during this follow-up period. Results of any revascularization procedure are limited by the progressive nature of the disease. Many post-CABG patients in our experience have had more than one PTCA procedure over the years as new stenoses have developed. This ability to achieve effective revascularization while avoiding multiple operations is a significant benefit. Implications of this study. The report by Ernst and associates I parallels previous studies indicating that in carefully selected post-CABG patients, PTCA can be performed with satisfactory safety and good long-term results. Usefulness of this study to make clinical decisions is limited by the lack of guidelines for patient selection for PTCA and by the low restudy rate. Selection of post-CABG patients for PTCA. PTCA should be considered in post-CABG patients when symptoms are disabling and angiographically suitable lesions are presentin the native coronary arteries, vein grafts (distal anastomosis better than midportion or proximal lesions), or internal mammary artery anastomoses. PTCA should be avoided if ( I) acute occlusion of the vessel or vessels dilated would produce cardiogenic shock, (2) the vessel to be dilated is of major importance and intra-aortic balloon pumping is not feasible because of iliac disease or if venous conduits are not readily available, or (3) if multiple or large, irregular vein graft lesions are present suggesting a high risk of distal embolization.
John S. Douglas, Jr., M.D. Spencer B. King Ill, M.D. Gary S. Roubin, M.B., Ph.D. Andreas Gruentzig Cardiovascular Center Departments of Medicine and Radiology Emory University School of Medicine Atlanta, Ga. 30322 REFERENCES 1. Ernst SMPG, van der Feltz TA, Ascoop CAPL, et al. Percutaneous transluminal coronary angioplasty in patients with prior coronary artery bypass grafting: longterm results. J THORAC CARDIOVASC SURG 1987;93:26875. 2. Douglas JS, Gruentzig AR, King SB, et al. Percutaneous transluminal coronary angioplasty in patients with prior
The Journal of Thoracic and Cardiovascular Surgery
coronary bypass surgery. J Am Coli Cardiol 1983;2:74554. 3. Corbelli J, Franco I, Hollman J, Simpfendorfer C, Galan K. Percutaneous transluminal coronary angioplasty after previous coronary artery bypass surgery. Am J Cardiol 1985;56:398-403. 4. Dorros G, Johnson WD, Tector AJ, Schmahl TM, Kalush SL, Janke L. Percutaneous transluminal coronary angioplasty in patients with prior coronary artery bypass grafting. J THORAC CARDIOVASC SURG 1984;87:17-26. 5. Reeder GS, Bresnahan JF, Holmes DR, et al. Angioplasty for aortocoronary bypass graft stenosis. Mayo Clin Proc 1986;61:14-9. 6. Block PC, Cowley MJ, Kaltenbach M, Kent KM, Simpson J. Percutaneous angioplasty of stenoses of bypass grafts or of bypass graft anastomotic sites. Am J Cardiol 1984;53:666-8. 7. Zaidi AR, Hollman JL. Percutaneous angioplasty of internal mammary artery graft stenosis: case report and discussion. Cathet Cardiovasc Diagn 1985;11:603-8. 8. Lytle BW, Loop FD, Cosgrove DM, et al. Fifteen hundred coronary reoperations: results and determinants of early and late survival. J Am Coli Cardiol 1986; 7:31A. 9. Hall RB, Elayda MA, Gray AG, Cooley DA. Reoperation for coronary artery disease. J Am Coli Cardiol 1986;7:32A. 10. Brenowitz J, Dorros G, Schley L, Johnson WD. Coronary artery bypass graft surgery for the third time or more: the results of 90 consecutive operations. J Am Coli Cardiol 1986;7:31A. 11. Kirklin JW, Barratt-Boyes BG. Cardiac surgery: morphology, diagnostic criteria, natural history, techniques, results and indications. New York: John Wiley and Sons, 1986;256. 12. Anderson HV, Leimgruber PP, Roubin GS, Douglas JS Jr, King SB III, Gruentzig AR. Primary angiographic success rates of percutaneous transluminal coronary angioplasty. Am J Cardiol 1985;56:712-7; 13. Bredlau CE, Roubin GS, Leimgruber PP, Douglas JS Jr, King SB III, Gruentzig AR. In-hospital morbidity and mortality in patients undergoing elective coronary angioplasty. Circulation 1985;72:1044-52. 14. Hinohara T, Simpson JB, Phillips HR, et al. Transluminal catheter reperfusion: A new technique to reestablish blood flow after coronary occlusion during percutaneous transluminal coronary angioplasty. Am J Cardiol 1986; 57:684-6. 15. Keon WJ, Heggtveit HA, Leduc J. Perioperative myocardial infarction caused by atheroembolism. J THORAe CARDIOVASC SURG 1982;84:849-55. 16. Douglas J, King S, Robinson K, Schlumpf M. Percutaneous transluminal angioplasty in aortocoronary venous graft stenosis: immediate results and complications. Circulation 1986;74(Pt 2):11363. 17. Douglas J, King S, Roubin G, Schlumpf M. Percutaneous angioplasty of venous aortocoronary graft stenoses: late
Volume 93 Number 2 February 1987
angiographic and clinical outcome. Circulation 1986; 74(Pt 2):I1281. 18. Loop FD, Cosgrove DM. Repeat coronary bypass surgery: selection of cases, surgical risks, and long-term outlook. Mod Cone Cardiovasc Dis 1986;55:31-6.
Response We are pleased that our manuscript is being enhanced by the discussion of our colleagues from Emory University. However, among their comments are two points that perhaps need further clarification. With regard to restenosis rates, we agree that the percentage of patients being restudied angiographically (49%) is not large, but it is much larger than in any other report on PTCA in this subgroup of patients. Such patients are more likely to refuse control angiography than are primary PTCA candidates. The denominator used in the calculation of restenosis rates is obviously the number of patients having a repeat angiographic study. Therefore, it is more likely that we encountered a falsely high estimate of the actual restenosis rate than a falsely low one.
PTCA in patients with prior CABG
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We disagree with Douglas and associates about the lack of implications of our study for clinical decision making. The definition of angiographically suitable lesions will always remain a point of discussion. However, we have demonstrated that middle or proximal vein graft lesions can also be safely dilated with better results than those reported elsewhere in the literature. We agree that PTCA of multiple, very large, or highly irregular graft lesions should be avoided, but this is also true of lesions in the native coronary system. Therefore, we do not believe this warrants new guidelines. We cannot understand why one should avoid PTCA in vessels in which occlusion might produce cardiogenic shock. Instead, we base our decisions on angiographic suitability rather than myocardial areas at risk. Our good success with PTCA of proximal stenoses in large jump or snake grafts (not specifically mentioned) underlines this. H. W Thijs Plokker, M.D., Ph.D. Sjef M. P. G. Ernst, M.D. Nieuwegein, Utrecht, The Netherlands
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