Surgical revascularization following unsuccessful percutaneous transluminal coronary angioplasty

J

THoRAc CARDIOVASC SURG

84:342-348, 1982

Surgical revascularization following unsuccessful percutaneous transluminal coronary angioplasty From September, 1980, through August, 1981, 353 patients underwent attempted percutaneous transluminal coronary angioplasty (PTCA). Twenty-seven patients (7.6%) subsequently underwent elective myocardial revascularization without death or complicating PTCA. Surgical support in the first 2 months involved a fully-staffed operating room standing idle. During the last 10 months, patients requiring emergency revascularization were accommodated in the first operating room available. All 17 patients undergoing emergency revascularization had severe chest pain and 12 patients had ST-segment elevation on the electrocardiogram. The average time from onset of ischemia to revascularization was 135 minutes and did not change over the period of study. Improvement in the electrocardiogram and myocardial function were frequently noted with restoration offlow by the vein graft. Two patients (12%) required inotropic drug support following revascularization. All 12 patients with ST-segment elevation preoperatively had elevated myocardial enzyme levels postoperatively, including five patients (29%) with new Q waves on the electrocardiogram. Myocardial necrosis did not correlate with time to revascularization, number of diseased vessels, the artery being instrumented, the mechanism of ischemia, or the presence of collateral flow. There were no deaths. Because of the high incidence of myocardial infarction despite prompt revascularization, we now routinely insert the intra-aortic balloon pump in the catheterization laboratory in patients with refractory myocardial ischemia requiring emergency revascularization, Prompt safe revascularization for acute ischemia following PTCA can be achieved without expensive and inefficient standby of cardiac surgical facilities. Transmural myocardial ischemia following complicated PTCA is frequently 'associated with evidence of myocardial necrosis despite prompt surgical revascularization. Greater salvage of ischemic myocardium may be possible if the intra-aortic balloon pump is used in the interval between PTCA-induced injury and surgical revascularization.

Douglas A. Murphy, M.D., Joseph M. Craver, M.D., Ellis L. Jones, M.D., Andreas R. Gruentzig, M.D., Spencer B. King III, M.D., and Charles R. Hatcher, Jr., M.D.,

Atlanta, Ga.

Acute myocardial ischemia complicating percutaneous transluminal coronary angioplasty (PTCA) often necessitates emergency myocardial revascularization.' Immediate availability of cardiac surgical personnel and facilities is a prerequisite for any institution performing PTCA.2-4 The role and organization of this surgical support continues to be defined as PTCA evolves in the care of patients with coronary artery disease. This report reviews the surgical experience

with patients having undergone PTCA during the first year of active clinical experience with PTCA at Emory University Hospital (EUH). Materials and methods

From the Joseph B. Whitehead Department of Surgery, Emory University School of Medicine, Atlanta, Ga. Received for publication Dec. 17, 1981. Accepted for publication Jan. 26, 1982. Address for reprints: Joseph M. Craver, M.D., Emory University Clinic, 1365 Clifton Rd., NE, Atlanta, Ga. 30322.

From September, 1980, through August, 1981, 353 patients underwent attempted PICA at EUH (Fig. 1). Surgical support for a PICA procedure performed during the first 2 months of the study period involved a cardiac operating room standing empty with a full contingent of personnel available. In the third and fourth months of the study period, PICA procedures were performed at times when a cardiac operating room was empty between elective operations and at the end of the day. During the last 8 months of the study period, there was no formal coordination between PICA procedures

342

0022-5223/82/090342+07$00.70/0 © 1982 The C. V. Mosby Co.

Volume 84 Number 3 September. 1982

and the cardiac surgical schedule. Patients who required emergency myocardial revascularization following PTCA during the last 8 months of the study were accommodated in the first operating room available. There are four cardiac surgical operating rooms at EUH. Patients requiring elective revascularization following unsuccessful but uncomplicated PTCA underwent the operation the same day during the first 2 months of the study but were placed on the elective schedule during the last 10 months of the study period. This report is based on the hospital records of 44 patients who underwent attempted PTCA and subsequent myocardial revascularization at EDH. The protocol and technical aspects of the PTCA procedure have been previously described in detail. 5 The EDH protocol for cardiac anesthesia and operation for this group of patients was the same as prescribed for the patients undergoing emergency cardiac revascularization and has been previously reported. 6. 7 Rapid cannulation techniques were employed to get the patient on full cardiopulmonary bypass as quickly as possible, so that the work interval required of the acutely ischemic myocardium would be reduced. Following completion of the coronary revascularization, the heart in a normally conducted or paced rhythm was perfused on bypass with the ventricle empty for a minimum of 30 minutes prior to any attempt to wean from cardiopulmonary bypass. It was during this "rest" interval that we often observed improvement in color and contractility in the previously discolored, akinetic ischemic area. Substantiation of these benefits of limited prolongation of cardiopulmonary bypass has recently been reported." Evidence of myocardial infarction was determinedby postoperative electrocardiographic changes and elevations in myocardial and total serum creatine kinase. The 44 patients are divided into two groups. Group I is composed of 27 patients who underwent uncomplicated but unsuccessful PTCA and subsequently had elective myocardial revascularization at EDH. Group II is composed of 17 patients who had acute myocardial ischemia during attempted PTCA and underwent emergency myocardial revascularization. Additionally, there were four patients who had unsuccessful, uncomplicated PTCA and chose to return to their home city for elective revascularization. They are not included in this analysis. Results Group I: Elective operation following attempted PTCA. Twenty-seven patients (27/353, 7.6%) had unsuccessful, uncomplicated PTCA and subsequently underwent myocardial revascularization at EUH. The

Percutaneous transluminal coronary angioplasty

343

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Fig. 1. PTCA caseload by month in its first year at Emory University Hospital, September, 1980, to September, 198I. PTCA. Percutaneous transluminal coronary angioplasty.

group comprised 22 men aged 38 to 62 years, mean 50.6 years, and four women aged 36 to 72 years, mean 51 years. Seventeen patients (62%) had one-vessel disease, seven patients (26%) had two-vessel disease, and one patient (4%) had three-vessel disease. Two patients (8%) had undergone previous bypass grafting and presented with stenosis of their native nonbypassed right coronary arteries. All patients had normal ventricular function and limiting angina despite medical regimens. In 25 patients (93%), the PTCA was not successful because the stenotic lesion could not be reached or crossed with the dilating catheter. One patient had successful coronary dilatation with a 30 mm Hg reduction in the gradient across the lesion, but continued to have angina secondary to medically refractory coronary spasm. One patient had a dissection of the right coronary artery with no ischemic symptoms or signs and was electively revascularized. The average delay from failed PTCA until elective operation during the last 10 months of the study period was 2.2 days. There were no perioperative myocardial infarctions. One patient required re-exploration for bleeding following revascularization, which had been performed within 24 hours after PTCA. There were no deaths. Group II: Emergency operation following attempted PTCA. Seventeen patients (17/353, 4.8%) underwent emergency myocardial revascularization following attempted PTCA. Data on each of the 17 individuals are presented in Table I. There were 14 men aged 36 to 67 years, mean age 53.3 years, and three women aged 59 to 68 years, mean 62.3 years. Thirteen patients (76%) had one-vessel disease, two (12%) had two-vessel disease, and one patient (6%) had threevessel disease. One patient (6%) had undergone previous myocardial revascularization, but stenosis had developed in the vein graft to the right coronary artery.

The Journal of Thoracic and Cardiovascular Surgery

344 Murphy et al.

Table I. Patients requiring emergency revascularization following PTCA Patient I

2 3 4 5 6 7 8 9 10 II

12 13

14 15 16 17

67 72

43 55 38 59 52 48 56 53 60

50 55 54 68 36 58

M M M M M F

M M M M F

M M M F

M M

No. of diseased coronary arteries

PTCA

Injury

Ischemic ECG signs

Myocardial infarction

One One Two Three One One One One One One One One One Two One One Two

LAD RCA LAD RCA RCA RCA LAD LAD RCA RCA LAD LAD RCA RCA graft LAD LAD LAD

Dissection Dissection Occlusion Dissection Dissection Dissection Occlusion Occlusion Dissection Dissection Dissection Occlusion Dissection Occlusion Dissection Dissection Dissection

ST No No ST ST No No ST ST ST ST ST ST ST ST ST No

Yes No No Yes Yes No No Yes Yes Yes Yes Yes Yes Yes Yes Yes No

Legend: PTCA. Percutaneous transluminal coronary angioplasty. ECG, Electrocardiographic. LAD. Left anterior descending coronary artery. RCA, Right coronary artery.

Table II. Operative results for emergency surgical revascularization for acute myocardial ischemia complicating PTCA

Complications

Myocardial infarction New Q waves on ECG Loss of R waves on ECG Elevated myocardial enzymes Bleeding necessitating re-exploration Inotropic support required

12 5 3 4 1 2

71 29 18 24 5.9 12

All patients had normal ventricular function and limiting angina despite medical regimens. The indication for emergency operation in all 17 patients was ischemic cardiac pain secondary to interruption of flow in the instrumented artery. In every case, the ischemia was unresponsive to intracoronary nitroglycerin, calcium blockers, and attempts to reopen the acutely occluded artery with streptokinase." In 12 patients, the unremitting pain was accompanied by ST-segment elevation in electrocardiographic leads, reflecting the distribution of the instrumented artery. Immediate angiograms demonstrated that 12 patients had severe dissections of the instrumented artery and five had total occlusions. At operation, seven patients had obviously discolored and dysfunctional myocardium distal to the injured artery. Four patients with coronary artery dissections had

gross periarterial hemorrhage. Twelve patients received single bypass grafts and five patients received two grafts, The average time from the onset of pain in the catheterization laboratory to perfusion of the ischemic myocardium by completed aorta-coronary artery vein grafts was 135 minutes, ranging from 75 to 210 minutes. This time interval did not change significantly over the study period despite the relaxation in the coordination of the PTCA and cardiac surgical schedules. Improvement in electrocardiographic signs of myocardial injury and return of contractility in the ischemic area were frequently noted with restoration of flow to the segment of ischemic muscle. Only two patients required inotropic drug support to be separated from cardiopulmonary bypass. In both cases, this support was successfully discontinued within 24 hours. The results of operation for Group II patients are presented in Table II. The 12 patients who arrived in the operating room with signs of acute ischemia on the electrocardiogram showed evidence of myocardial infarction on postoperative studies. Five patients had transmural myocardial infarctions as manifested by new Q waves in postoperative electrocardiograms and elevated myocardial enzymes. In all instances, the injury occurred in the distribution of the instrumented artery. In seven additional patients, myocardial infarction was evidenced by elevated myocardial enzymes; three of these patients also had loss of R-wave voltage in leads predicted by the location of the PTCA injury. All 12 patients with electrocardiographic changes pre-

Volume84 Number3 September, 1982

operatively had evidence of myocardial infarction postoperatively. There was no correlation between postoperative myocardial infarction and the time interval from injury to revascularization, the number of diseased native vessels, the coronary artery being instrumented, the anatomic mechanism provoking the acute ischemia (i.e., occlusion vs. dissection), or the presence or absence of visible collateral flow to the distal diseased coronary artery. Postoperatively, all of the patients had a greater than normal bleeding time, attributed to the antiplatelet agents administered prior to PICA. Mediastinal drainage was increased postoperatively in all patients, but only one required re-exploration. One patient required repair of a false aneurysm of the femoral artery at the catheterization site. The angioplasty catheters are now routinely left in place in the femoral vessels until the patient's systemic heparinization has been reversed after cardiopulmonary bypass. The average hospital stay following operation was 7.7 days. No patients required therapy for congestive heart failure at discharge, but two patients were on a regimen of long-term antiarrhythmic therapy when discharged. There were no hospital deaths. Follow-up data were available on 15 of 17 patients. Two could not be reached and have not seen their physician since PICA and operation. The other 15 patients are alive 7 to 17 months following operation. Fourteen of the 15 patients are free of cardiac symptoms and without physical limitations. One has anginal symptoms suspected to be associated with coronary spasm, which had been demonstrated prior to PICA. Followup ventricular function studies and coronary arteriography have not been routinely performed. Discussion

Immediate availability of cardiac surgical facilities and personnel is a prerequisite for a PICA program. Most important the capability of performing immediate myocardial revascularization when acute ischemia with hemodynamic decompensation develops as a complication of PICA. In our series, 4.6% of patients undergoing PICA required emergency coronary bypass. This rate is less than a nationwide registry citing a 7% incidence of emergency operation following PICA. 1 Less urgent but also important is the capability to perform elective myocardial revascularization for patients whose symptoms could not be improved by PICA. The criteria for operation in these patients are the same as in non-PICA patients. The patient undergoing PICA for proximal, singlevessel disease of short duration may be subjected to

Percutaneous transluminal coronary angioplasty

3 45

profound myocardial ischemia if the stenosis in the diseased artery is abruptly increased by dissection or ocelusion." Twelve of our patients had transmural myocardial ischemia in this setting and another five patients had persistent ischemic chest pain without electrocardiographic changes. The ischemia may be caused by coronary dissection with mechanical limitation of flow but may also occur with lesser degrees of arterial dissection associated with severe coronary spasm. Some degree of arterial dissection is evident in the majority of PICA patients as a result of the dilatation itself, but the determinants of coronary arterial spasm which is frequently associated are poorly understood;" Administration of nifedipine and intracoronary nitroglycerin may alleviate coronary spasm in many cases, although often the relief is only transient. Coronary occlusion may result from extreme spasm or exposure to the blood of a thrombogenic surface secondary to disruption of the atheromatous plaque." In such instances, intracoronary passage of a catheter with distal infusion of streptokinase may temporarily reopen the coronary artery and eliminate the myocardial ischemia. 9. 11 These measures are carried out while preparations are being made for surgical revascularization. If the ischemic process persists, emergency myocardial revascularization is undertaken and no time delay has been incurred. ,The objectives of emergency surgical revascularization are to support the acutely ischemic myocardium with rapid institution of cardiopulmonary bypass and to bypass the process provoking the acute ischemia. In this manner, the extent of myocardial necrosis is limited and the acutely ischemic myocardium, which otherwise might have become necrotic, is reclaimed. 7. 12-17 The natural history of acute coronary artery injury occurring during cardiac catheterization is not well documented. Bourassa and Noble'" reported on three patients with right coronary artery dissections who were treated conservatively and had no myocardial infarctions despite evidence of ischemic pain in two patients. Guss and associates." reporting on coronary occlusion during coronary angiography at the Massachusetts General Hospital, described five patients with right coronary artery dissections with transmural ischemia who were treated medically. Four of these patients developed transmural infarctions, but none of them died. This is in distinct contrast to a large series of catheter-induced coronary occlusions managed medically in a Veterans Administration Hospital study, in which the mortality was 86%.20 Studies with a canine model have shown significant salvage of ischemic myocardium when revasculariza-

The Journal of

346 Murphy et al.

Thoracic and Cardiovascular

Surgery

tion is performed within 3 hours of coronary occlusion. 12 - 14 Similar observations have been made in patients when acute ischemia from coronary thrombosis is reversed with streptokinase. II With the patient in the hospital and the coronary anatomy well defined at the time of PTCA-related arterial injury, revascularization can be achieved within 3 hours of the onset of the ischemic insult. Cohn and associates" reported on six patients with coronary occlusion occurring during cardiac catheterization who underwent operation within 3 hours, with no deaths. The 17 patients in the present report underwent emergency revascularization for acute ischemia following PTCA, again with no deaths. Although emergency revascularization for acute ischemia following PTCA was performed with no deaths, the degree of salvage of acutely ischemic myocardium is difficult to quantify. Twelve of our patients were taken to operation during the evolution of an acute myocardial infarction with transmural ischemic electrocardiographic changes persisting from the time of PTCA injury, despite maximal medical therapy and angiocatheter techniques. Ischemic changes appeared to improve only with re-establishment of flow to the injured myocardium via the completed aorta-coronary graft. All 12 of these patients, however, still manifested evidence of myocardial injury ·postoperatively. This is similar to the experience of others. 2, 5, 21 However, the relative size of the infarction compared to the size it might have attained had it been allowed to evolve without revascularization cannot be directly determined. Absolute values of serum enzymes are difficult to interpret because size of myocardial infarctions may be overestimated from serum creatine kinase determinations taken following reperfusion of ischemic myocardium." Five other patients in our series had refractory ischemic pain without electrocardiographic changes at the time of PTCA arterial injury. All underwent emergency revascularization. None of these patients had evidence of myocardial infarction by electrocardiographic or enzyme criteria postoperatively; however, their clinical course had they been treated medically is unknown. Recent technical advances using thallium 201 may in the future allow documentation of myocardial salvage in patients undergoing operation for ischemia after unsuccessful PTCA. II The value of objective documentation of preservation of left ventricular function in these patients will be important, not only in assessing the efficacy of operative therapy in these patients, but also in the overall evaluation of PTCA as a therapeutic modality. We advocate emergency surgical revascularization for all patients with refractory acute ischemia com-

plicating PTCA, despite the persistent evidence of myocardial infarction following the revascularization and the absence of objective evidence that emergency revascularization has salvaged ischemic myocardium. Although we lack definitive evidence of myocardial salvage from prompt revascularization, we remain impressed by improvement in measurable hemodynamic parameters (decreased pulmonary capillary wedge pressure, increased cardiac index, lower inotrope requirements) and clinical observations of improved electrocardiographic signs and myocardial contractility when blood flow is restored to the ischemic muscle. In an effort to minimize the extent of myocardial necrosis occurring before coronary flow can be reestablished by vein graft, we are currently evaluating the efficacy of early institution of intra-aortic balloon pumping in patients with persistent acute ischemia complicating PTCA. 23 Insertion of the intra-aortic balloon catheter can be expedited by passage of a flexible guide wire into the opposite femoral artery while pharmacologic and angioplastic attempts to reverse the acute ischemia are being made. If measures to treat the acute ischemia are successful, the guide wire may be harmlessly removed. If persistent ischemia is refractory to therapeutic measures, prompt percutaneous insertion of the intra-aortic balloon catheter can be carried out over the guide wire. Preparation in advance of the groin opposite that used for the PTCA catheterization expedites the prompt insertion of the guide wire and balloon pump catheter by the percutaneous technique. Theoretically, intra-aortic balloon pumping may reduce the severity of myocardial ischemia by systolic afterload reduction and diastolic augmentation of coronary blood flow and thereby may contribute to greater myocardial salvage with subsequent surgical revascularization. 16, 23 Intra-aortic balloon pumping may be particularly helpful when a cardiac operating room is not immediately available. Identification of patients who may be at increased risk of ischemic injury during PTCA is aided by the following: (1) absence of visible collateral vessels to the artery distal to the proximal occluding stenosis, (2) measurement via the PTCA catheter of low pressure in the artery distal to the stenosis prior to performance of the angioplasty, (3) occurrence of pain and ST-T signs of ischemia when the PTCA balloon is inflated and the artery completely obstructed. For these patients and any other patients believed to be at high risk, it is advisable to have support procedures as well as the intra-aortic balloon pump on standby in the angioplasty suite at the time of PTCA. We presently consider the indications for emergency

Volume 84 Number 3 September, 1982

revascularization following PTCA to apply to two groups of patients: (1) patients with coronary arterial injury resulting in ischemic pain associated with electrocardiographic changes of ischemia, and (2) patients with coronary arterial injury and acute ischemic pain in the absence of electrocardiographic changes if the extent of myocardium in jeopardy is likely to be clinically significant in case of infarction;" In both groups of patients, the decision for surgical revascularization is made after attempts to reverse any components of spasm or thrombosis have been exhausted and our clinical impression is that myocardial infarction is imminent and progressive. It is our belief, based primarily on clinical observations, that these patients are best served by emergency revascularization in an attempt to arrest the continuing ischemic process and salvage myocardium. Large coronary dissections with limitation of flow but neither symptoms nor electrocardiographic changes may be considered for nonoperative therapy or semielective operation. The extent of myocardium at jeopardy and the available collateral blood supply to the area should be considered in deciding on elective surgical revascularization or nonoperative therapy. Smaller, limited dissections without symptoms are common following PTCA and should not be considered an indication for operation." Likewise, occlusions of small coronary arteries or branches with or without symptoms may be handled medically. The organization of surgical support for the PTCA team has matured over the past year at our institution. Numerous authors have advocated having complete cardiac surgery teams on a standby basis."? In our initial 2 months with PTCA, we had an open cardiac operating room as a backup. As our experience with PTCA increased, surgical backup evolved to a system in which the patient requiring emergency revascularization is accommodated in the first available operating room by the first available surgical and anesthesia team. This system has functioned well without any increase in the time period from the onset of ischemia to revascularization. This organization has allowed our cardiac surgery facilities to function with maximum efficiency while still providing proficient support for an active PTCA program. Smaller institutions may find it advisable to coordinate plans whereby the PTCA procedures would be done during natural breaks or at the end of the day's surgical schedule. However, inefficient utilization of cardiac surgical facilities and personnel is to be avoided, since this would increase the indirect costs of a PTCA program and must be considered in any analysis comparing the cost of PTCA to that of primary surgical coronary revascularization.

Percutaneous transluminal coronary angioplasty

3 47

We would like to thank Mr. Tom Thompkins for his assistance in gathering this material.

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The Journal of Thoracic and Cardiovascular Surgery

21 Vlietstra RE, Holmes DR, Smith HC, Hartzler GO, Orszulak TA: Percutaneous transluminal coronary angioplasty. Initial Mayo Clinic experience. Mayo Clin Proc 56:287-293, 1981 22 Vatner SF, Barg H, Manders WT, Maroko PR: Effects of coronary artery reperfusion on myocardial infarct size calculated from creatine kinase. J Clin Invest 63: 10481056, 1978 23 Gold HK, Leinbach RC, Sanders CA, Buckley MJ, Mundth ED, Austen WG: Intra-aortic balloon pumping for control of recurrent myocardial ischemia. Circulation 47:1197-2037,1973 24 Rackley CE, Russell RO, Mantle JA, Rogers WJ, Papapietro SE: Modem approach to myocardial infarction. Determination of prognosis and therapy. Am Heart J 101: 75-85, 1981 25 Geraci AR, Krishnaswanii V, Selman MW: Aortacoronary dissection complicating coronary arteriography. J THORAC CARDIOVASC SURG 65:695-698, 1973