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Impact of Different Patency Criteria on Long-term Results of Femoropopliteal Angioplasty: Analysis of 106 Consecutive Patients with Claudication
Jascular Therapy
Impact of Different Patency Criteria on ~ o n g - t e r m Results of ~emoropopliteal Angioplasty: Analysis of 106 Consecutive Patients with Claudicationl Pekka J. Matsi, MD Hannu I. Manninen, MD, MSc Index terms: Arteries, extremities, 92.128,92.721 Arteries, stenosis or obstruction, 92.721 Arteries, transluminal angioplasty, 92.128
JVIR 1995; 6:159-163 Abbreviations: ABI = ankle-brachial index, PTA = percutaneous transluminal angioplasty
PURPOSE: To assess the impact of different patency criteria on long-term results after percutaneous transluminal angioplasty (PTA) of femoropopliteal arteries. PATIENTS AND METHODS: The results of femoropoplitealPTA in 106 consecutive patients with claudication (140 treated limbs) were analyzed. The treated artery segment was considered patent if (a) the ankle-brachial index (ABI) had increased by more than 0.10 initially and not deteriorated by more than 0.15 from the maximum early postprocedural level and ( b )the ABI was consistently at least 0.15 above the preprocedural level. The third criteria was based on patients' subjective assessment of patency. Initial failures were either included or excluded and both primary (the outcome of the original PTA) and secondary patency (also repeated PTAs included) were determined. RESULTS: When the different criteria were applied, the patency rates at 3 years ranged from 42%to 82%in this patient population. CONCLUSION: These results stress the importance of uniform criteria when results of different kind of vascular interventions are reported. lack of uniform standards for evaluating and reporting the results of therapeutic interventions for peripheral vascular disease has contributed to a variation in the reported long-term patencies of percutaneous transluminal angioplasty (PTA) (1,2). Both objective criteria, based mainly on the ankle-brachial index (ABI), and subjective assessment of patency, on the basis of palpable pulses or continued symptomatic improvement, have been used (1,2). Estimations of primary patency (the outcome of the original PTA) and secondary patency (including repeated PTAs) have not been clearly differentiated in published reports. Finally, initial failures have been either included in or excluded from the results. The published 5year patencies following femoropopliteal angioplasty have varied from T H E
'
From the Department of Clinical Radiology, Kuopio University Hospital, Puijonlaaksontie 2, FIN-70210 Kuopio, Finland. Received May 12,1994; revision requested August 10; revision received September 19; accepted September 28. Address reprint requests to P.J.M. O SCVIR, 1995
38% to 73% (3-5). To overcome these problems, the Standards of Practice Committee of the Society of Cardiovascular and Intementional Radiology (SCVIR) and the editorial board of the Journal of Vascular and Interuentional Radiology (JVIR)have decided to adopt a modified version of the "Standards for Evaluating and Reporting the Results of Surgical and Percutaneous Therapy for Peripheral Arterial Disease" proposed by Rutherford and Becker (1).According to this recommendation, patency should be determined by objective means, which include angiography, duplex or color flow ultrasound (US), computed tomography, magnetic resonance imaging, radionuclide angiography, or appropriate segmental limb pressure index. Recently, a new version of this recommendation applied specifically to pe-
160
Journal of Vascular and Interventional Radiology
March-April 1995
Results of Kaplan-Meier Analysis Secondary Patency Rate (%)
Primary Patency Rate (%) Patency Criteria Rutherford ABI > 0.15 Subjective
Initial Failures Included
Initial Failures Excluded
Initial Failures Included
Initial Failures Excluded
1y
2~
3~
1Y
2~
3~
1~
2~
3~
1~
2~
3Y
47 (4) 48 (4) 59 (4)
42 (5) 44 (5) 56 (5)
42 (5) 44 (5) 56 (5)
52 (5) 53 (5) 66 (5)
47 (5) 49 (5) 63 (5)
47 (5) 49 (5) 63 (5)
63 (4) 64 (4) 75 (4)
59 (4) 61 (4) 73 (4)
59 (4) 61 (4) 73 (4)
71 (4) 72 (4) 84 (3)
66 (5) 68 (5) 82 (4)
66 (5) 68 (5) 82 (4)
Note.-Numbers
in parentheses are standard errors.
ripheral endovascular procedures has been published in the Journal of Vascular Surgery (6). We recently reported our results of femoropopliteal angioplasty in 106 consecutive patients with claudication by using the criteria of Rutherford and Becker (7). The purpose of this work is to evaluate how the achieved results change when different kinds of objective and subjective patency criteria are used.
PATIENTS AND METHODS Our patient population consisted of consecutive patients with claudication in whom the main lesion was in the femoropopliteal artery and in whom no earlier angioplasty or vascular surgery was performed in the treated limb. Altogether, 106 patients (with 140 limbs) fulfilling these criteria were treated during the study period (between October 1989 and December 1991) in the Department of Clinical Radiology of Kuopio University Hospital. The follow-up time was 12-36 months (mean, 19 months). Thirteen patients were lost to follow-up during the study period. The patients were followed up a t 1month, 3 months, 6 months, and yearly thereafter following PTA. The initial evaluation of the patients and follow-up investigations included subjective history, physical examination, and determination of ABI. Duplex US examination of the common femoral and popliteal arteries was performed in all patients immediately before PTA
and just before discharge. The patients' subjective self-evaluation of outcome was stratified into five categories: marked improvement, improvement, no change, mild worsening, marked worsening. Determination of the hemodynamic success of the PTA was based on the results a t duplex US. Doppler velocity waveforms were classified into three categories: normal (diastolic backflow present), no diastolic backflow, and no flow. Hemodynamic success was defined as an improvement in the category of the Doppler velocity waveform or a t least doubling of the peak velocity in the popliteal artery distal to the site of angioplasty. Two kinds of objective criteria were used in the determination of patency. First, the treated artery segment was considered patent if the resting ABI had increased by more than 0.10 initially and not deteriorated by more than 0.15 from the maximum early postprocedural level (the criteria of Rutherford and ~ e c k e r )Unless . otherwise mentioned, the objective success and failure in this report refer to these criteria. Second, the treated artery segment was considered patent if the resting ABI was consistently a t least 0.15 above the preprocedural level (6).When the patency rate was calculated with subjective criteria, the treatments that were successes according to objective ABI criteria were considered subjective successes. Also, the treatments that were failures according to objective ABI criteria were considered subjec-
tive successes if they were classified by the patient in the categories "marked improvement" or "improvement." If the results were classified by the patient in the categories "no change," "mild worsening," or "marked worsening" they were considered to be subjective failures. Follow-up angiography was performed when new invasive treatment was needed based on the clinical situation of the patient. The cumulative patency rate versus time of follow-up for the 140 treated limbs was calculated with the KaplanMeier method. The statistical difference between survival curves was determined by means of the log-rank (Mantel-Cox) test. The primary patency rate was based on the results of the original PTA. In calculations of the secondary patency rate, results of repeated PTA procedures were also included. In patients requiring surgical interventions, treatments were regarded as failures. Survival curves were generated both by including and excluding the initial failures in the analysis. The Pearson x2 test for discrete variables and univariate logistic regression analysis for continuous variables were applied to identify the determinants of subjective patency. P c .05 was considered the level of statistical significance.
RESULTS The hemodynamic success rate for all 140 treated limbs was 89%; 99% for femoropopliteal dilations
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% Patency rate
% Patency rate
om
1
l
0
O
I
0
Months
Months
2. Figures 1,2. (1)Results of survival analysis (Kaplan-Meiermethod) for the primary and secondary patency rates for all 140 treated limbs according to the different criteria used (see Table). Initial failures included. (2) Results of survival analysis (Kaplan-Meiermethod) for the primary and secondary patency rates according to the different criteria used (see Table) and excluding initial failures. Life-table data are available on request. 1.
and 80% for femoropopliteal recanalizations (7). The cumulative primary and secondary patencies versus time of follow-up according to the different criteria used and including/excluding initial failures are shown in the Table and Figures 1 and 2. Statistically, there were no significant differences among patency rates obtained with the three criteria, but when the ABI criteria proposed by Rutherford and Becker were compared with subjective criteria, the difference in survival curves nearly reached statistical significance (P= .06). Primary patency rates differed significantly (all P = .01) from secondary patency rates when any of the criteria were applied, whereas inclusion or exclusion of initial failures did not result in significant differences between survival curves (P = .14-.19) By far, the best long-term results were obtained by applying patients' subjective selfevaluation of outcome. By using the
objective ABI criteria, the results were identical except for three cases of femoropopliteal recanalizations in which the criteria of Rutherford and Becker showed restenosis, while the other objective criteria showed patency. All three patients were subjective successes according to the criteria used. With the criteria of Rutherford and Becker, primary patency was lost during the follow-up period in 59 of the 140 treated limbs. In 36 of these 59 legs, restenosis (stenosis of at least 50% of normal diameter) was also angiographically verified and three patients who had undergone repeated angiography (failed PTAs according to the criterion of the ABI) showed development of a new lesion, while there was no restenosis a t the angioplasty site. PTA procedures in 24 of the 59 limbs (41%)were not failures with subjective criteria (13 classified as marked improvement and 11as improve-
ment by the patients). Among all patients whose primary treatment was successful, those who were subjective successes according to the criteria used at the end of follow-up had statistically significantly higher ABI values than those who were not (mean, 0.82 vs 0.60, respectively; P < .01). There were no significant differences between the ABI values of those patients with subjective success but objective failure and the patients with both subjective and objective failures. Among the patients with objective failures, those with subjective successes had slightly, though not statistically significantly, better runoff (when dichotomized as two to three Ygood runoffl vs zero or one ["poor" runoffl patent calf vessels) than those with subjective failures: 16 of 24 (67%)had good runoff in the former group versus 15 of 35 (43%) in the latter group (P = .07). There were no significant differences between the other tested variables: severity of the treated lesion (stenosis vs occlusion), severity of claudication (Fontaine IIA vs IIB), extensiveness of atherosclerotic disease in the treated limb (number of vessels with occlusions or stenosis over 50%), gender or age of the patient, or prevalence of diabetes. PTA procedures in five patients were objective successes but subjective failures. Further clinical and radiologic examinations revealed that besides claudication caused by atherosclerotic lower limb disease, two of them had spinal stenosis, one suffered from syndroma ischiadicum, and one had knee arthrosis. One patient was not known to have any other medical explanation for his symptoms.
DISCUSSION PTA was first introduced in 1964 and becamk an accepted technique in the mid-1970s when balloon catheters were developed. Since then it has gained broad acceptance in clinical practice. However, the greater
162
Journal of Vascular and Interventional Radiology
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than 30% range of differences in reported outcomes of both iliac and femoropopliteal balloon angioplasty have made the literature on this subject quite confusing (1,2). Variations in long-term results can be partly due to differences in patient selection but are without doubt partly due to the lack of uniform and objective criteria for defining successful outcome. SCVIWJVlR have recently adopted objective criteria (proposed by Rutherford and Becker) for evaluating and reporting the results of percutaneous therapy for peripheral arterial disease. According to these criteria ABI is one of objective means for determining patency. With ABI measurements, patency is determined by a consistent rise in the ABI (an increase of more than 0.10, and a less than 0.15 decrease below the early postprocedural maximum). By these standards initial failures must be included in the analysis, and primary and secondary patencies are clearly differentiated. Although ABI is an objective criteria for patency it does not help distinguish restenosis from a new lesion. In our work, 66% of restenoses according to ABI criteria were also angiographically verified and in 8% of cases, the reason for failure was a new lesion while the PTA-treated artery segment was widely patent. The increase in ABI after PTA can be minimal in cases of severe infrapopliteal disease, and on the other hand it can give erroneously high values in patients with calcified distal runoff vessels. However, its noninvasiveness and wide availability favor its use in routine clinical practice. Using the Rutherford criteria, we obtained primary patency rates of 47% a t 1year and 42% a t 2 and 3 years, which are seemingly low with respect to those reported by others (4,8-11). As far as we know, these strict objective ABI criteria have not been used as the sole determinant of outcome by other groups; other criteria, such as Doppler frequency analysis, treadmill exercise test, and subjective improvement, have been
utilized additionally in outcome evaluation (8-12). Further, we had a large number of patients with longsegment disease with a higher restenosis rate (7). In addition to using the ABI criteria of Rutherford and Becker, we also performed separate calculations applying ABI criteria proposed in the most recent recommendation of Ahn et al, in which the ABI must remain consistently a t least 0.15 above the preprocedural level to indicate patency (6). This produced long-term results that were only slightly better than those based on the criteria of Rutherford and Becker, however (Table). There was no difference in primary patency rate with use of either criteria when the treated femoropopliteal lesion was a stenosis. The difference was due to three cases of femoropopliteal recanalizations, in which ABI decreased more than 0.15 below the early postprocedural maximum but remained still a t least 0.15 above the preprocedural level. By far the best outcome figures were achieved by using the patients' subjective self-evaluation as the criteria for primary patency: 59% a t 1year and 56% at 2 and 3 years. If initial failures (15 of 140 limbs) are excluded, the 3-year primary patency rate is 5%-7% higher in this patient population, but in a population consisting solely of recanalizations with more initial failures, the difference would be greater. If initial failures are excluded, the reported results of angioplasty are based on the subset of patients with good initial technical outcome. This kind of data becomes less useful as a tool for predicting the potential benefit of PTA compared with surgical procedures. The secondary patency rate is useful in comparison of different kinds of vascular interventions, because it reflects the ultimate success that can be achieved. With the criteria of Rutherford and Becker the secondary patency rate was 59% at 3 years, and with subjective criteria it was 73% a t 3 years. Excluding initial failures, the secondary patency
rates a t 3 years were 66% and 82%, respectively. So, there is a range as great as 40% (42%-82%) in achieved patency rates a t 3 years in our patient population, depending on the outcome criteria used (Table). It is evident that conclusions based on the results of PTA, concerning for instance the clinical utility of this therapy, may be totally contradictory depending on how the results are reported. To find factors influencing subjective satisfaction, the subgroup of patients with objective failure but subjective success was compared with those with both objective and subjective failure. As many as 24 of 59 patients (41%)with objective failure reported subjective improvement in their symptoms a t the time of objective failure and did not require additional invasive treatment. Subjective satisfaction was slightly, though not statistically significantly, associated with good peripheral runoff. The association can be due to the ability of patients with good runoff to form sufficient collaterals to be able to benefit from exercise therapy. It is known that for the majority of patients with claudication, improvement in walking distance and subjective satisfaction can be achieved with a simple exercise program (13). One can assume that in critical ischemia the meaning of different criteria is not as great, because treatment failures lead more easily to bypass operations or amputations (14). On the other hand, in claudicants the long-term risk for amputation is low (15). It would be ideal if we could recognize those claudicants who will develop critical ischemia and perhaps prevent or a t least delay this event by means of PTA. It is useful to realize that controversies in PTA results depending on the criteria used are not important for the patient with claudication for whom subjective improvement is the most essential factor. On the other hand, subjective failures after angioplasty can be due to other than atherosclerotic lower limb disease, as was
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found in four patients in our study. The range of 42%-82%of achieved patency rates at 3 years in our patient population stresses the importance of uniform criteria when angioplasty results are reported. Our work shows that there is a minimal difference in patency rates with use of the ABI criteria of either Rutherford and Becker or Ahn et al. Articles published using one or the other criteria can still be compared quite well. Applying solely subjective improvement as a patency criterion gives erroneously high patency rates compared with objective criteria and makes comparison of different kind of therapeutic interventions unreliable. References 1. Rutherford RB, Becker GJ. Standards for evaluating and reporting the results of surgical and percutaneous therapy for peripheral arterial disease. JVIR 1991; 2:169-174. 2. Rutherford RB. Standards for evaluating results of interventional therapy for peripheral vascular disease. Circulation 1991; 83(supplI):I6-1-11.
3. Becker GJ, Katzen BT, Dake MD. Noncoronary angioplasty. Radiology 1989; 170:921-940. 4. Capek P, McLean GK, Berkowitz HD. femoropopliteal angioplasty, factors influencing long-term success. Circulation 1991; 83(suppl 1):I70-1-80. 5. Johnston KW. Femoral and popliteal arteries: reanalysis of results of balloon angioplasty. Radiology 1992; 183:767-771. 6. Ahn SS, Rutherford RB, Becker GJ, et al. Reporting standards for lower extremity arterial endovascular procedures. J Vasc Surg 1993; 17:1103-1107. 7. Matsi PJ, Manninen HI, Vanninen RL, et al. Femoropopliteal angioplasty in patients with claudication: primary and secondary patencies in 140 limbs with 1-3-year follow-up. Radiology 1994; 191:727-733. 8. Gallino A, Mahler F, Probst P, Nachbur B. Percutaneous transluminal angioplasty of the arteries of the lower limbs: a 5-year follow-up. Circulation 1984; 70:619-623. 9. Hewes RC, White RI Jr, Murray RR, et al. Long-term results of superficial femoral artery angioplasty. AJR 1986; 146:1025-1029. 10. Murray RR Jr, Hewes RC, White RI, et al. Long-segment femoro-
11.
12.
13.
14.
15.
popliteal stenoses: is angioplasty a boon or a bust? Radiology 1987; 162:473-476. Krepel VM,van Andel GJ, van Erp WFM, Breslau PJ. Percutaneous transluminal angioplasty of the femoropopliteal artery: initial and long-term results. Radiology 1985; 156:325-328. Johnston KW, Rae M, Hogg-Johnston SA, et al. Five-year results of a prospective study of percutaneous transluminal angioplasty. Ann Surg 1987; 206:403-413. Creasy TS, McMillan PJ, Fletcher EWL, Collin J , Morris PJ. Is percutaneous transluminal angioplasty better than exercise for claudication? Preliminary results from a prospective randomised trial. Eur J Vasc Surg 1990; 4:135-140. Matsi PJ, Manninen HI, Suhonen MT, Pirinen AE, Soimakallio S. Chronic critical lower-limb ischemia: prospective trial of angioplasty with 1-36 months follow-up. Radiology 1993; 188:381-387. Hertzer NR. The natural history of peripheral vascular disease: implications for its management. Circulation 1991; 83 (supp1I):I-12-1-19.
Impact of Different Patency Criteria on ~ o n g - t e r m Results of ~emoropopliteal Angioplasty: Analysis of 106 Consecutive Patients with Claudicationl Pekka J. Matsi, MD Hannu I. Manninen, MD, MSc Index terms: Arteries, extremities, 92.128,92.721 Arteries, stenosis or obstruction, 92.721 Arteries, transluminal angioplasty, 92.128
JVIR 1995; 6:159-163 Abbreviations: ABI = ankle-brachial index, PTA = percutaneous transluminal angioplasty
PURPOSE: To assess the impact of different patency criteria on long-term results after percutaneous transluminal angioplasty (PTA) of femoropopliteal arteries. PATIENTS AND METHODS: The results of femoropoplitealPTA in 106 consecutive patients with claudication (140 treated limbs) were analyzed. The treated artery segment was considered patent if (a) the ankle-brachial index (ABI) had increased by more than 0.10 initially and not deteriorated by more than 0.15 from the maximum early postprocedural level and ( b )the ABI was consistently at least 0.15 above the preprocedural level. The third criteria was based on patients' subjective assessment of patency. Initial failures were either included or excluded and both primary (the outcome of the original PTA) and secondary patency (also repeated PTAs included) were determined. RESULTS: When the different criteria were applied, the patency rates at 3 years ranged from 42%to 82%in this patient population. CONCLUSION: These results stress the importance of uniform criteria when results of different kind of vascular interventions are reported. lack of uniform standards for evaluating and reporting the results of therapeutic interventions for peripheral vascular disease has contributed to a variation in the reported long-term patencies of percutaneous transluminal angioplasty (PTA) (1,2). Both objective criteria, based mainly on the ankle-brachial index (ABI), and subjective assessment of patency, on the basis of palpable pulses or continued symptomatic improvement, have been used (1,2). Estimations of primary patency (the outcome of the original PTA) and secondary patency (including repeated PTAs) have not been clearly differentiated in published reports. Finally, initial failures have been either included in or excluded from the results. The published 5year patencies following femoropopliteal angioplasty have varied from T H E
'
From the Department of Clinical Radiology, Kuopio University Hospital, Puijonlaaksontie 2, FIN-70210 Kuopio, Finland. Received May 12,1994; revision requested August 10; revision received September 19; accepted September 28. Address reprint requests to P.J.M. O SCVIR, 1995
38% to 73% (3-5). To overcome these problems, the Standards of Practice Committee of the Society of Cardiovascular and Intementional Radiology (SCVIR) and the editorial board of the Journal of Vascular and Interuentional Radiology (JVIR)have decided to adopt a modified version of the "Standards for Evaluating and Reporting the Results of Surgical and Percutaneous Therapy for Peripheral Arterial Disease" proposed by Rutherford and Becker (1).According to this recommendation, patency should be determined by objective means, which include angiography, duplex or color flow ultrasound (US), computed tomography, magnetic resonance imaging, radionuclide angiography, or appropriate segmental limb pressure index. Recently, a new version of this recommendation applied specifically to pe-
160
Journal of Vascular and Interventional Radiology
March-April 1995
Results of Kaplan-Meier Analysis Secondary Patency Rate (%)
Primary Patency Rate (%) Patency Criteria Rutherford ABI > 0.15 Subjective
Initial Failures Included
Initial Failures Excluded
Initial Failures Included
Initial Failures Excluded
1y
2~
3~
1Y
2~
3~
1~
2~
3~
1~
2~
3Y
47 (4) 48 (4) 59 (4)
42 (5) 44 (5) 56 (5)
42 (5) 44 (5) 56 (5)
52 (5) 53 (5) 66 (5)
47 (5) 49 (5) 63 (5)
47 (5) 49 (5) 63 (5)
63 (4) 64 (4) 75 (4)
59 (4) 61 (4) 73 (4)
59 (4) 61 (4) 73 (4)
71 (4) 72 (4) 84 (3)
66 (5) 68 (5) 82 (4)
66 (5) 68 (5) 82 (4)
Note.-Numbers
in parentheses are standard errors.
ripheral endovascular procedures has been published in the Journal of Vascular Surgery (6). We recently reported our results of femoropopliteal angioplasty in 106 consecutive patients with claudication by using the criteria of Rutherford and Becker (7). The purpose of this work is to evaluate how the achieved results change when different kinds of objective and subjective patency criteria are used.
PATIENTS AND METHODS Our patient population consisted of consecutive patients with claudication in whom the main lesion was in the femoropopliteal artery and in whom no earlier angioplasty or vascular surgery was performed in the treated limb. Altogether, 106 patients (with 140 limbs) fulfilling these criteria were treated during the study period (between October 1989 and December 1991) in the Department of Clinical Radiology of Kuopio University Hospital. The follow-up time was 12-36 months (mean, 19 months). Thirteen patients were lost to follow-up during the study period. The patients were followed up a t 1month, 3 months, 6 months, and yearly thereafter following PTA. The initial evaluation of the patients and follow-up investigations included subjective history, physical examination, and determination of ABI. Duplex US examination of the common femoral and popliteal arteries was performed in all patients immediately before PTA
and just before discharge. The patients' subjective self-evaluation of outcome was stratified into five categories: marked improvement, improvement, no change, mild worsening, marked worsening. Determination of the hemodynamic success of the PTA was based on the results a t duplex US. Doppler velocity waveforms were classified into three categories: normal (diastolic backflow present), no diastolic backflow, and no flow. Hemodynamic success was defined as an improvement in the category of the Doppler velocity waveform or a t least doubling of the peak velocity in the popliteal artery distal to the site of angioplasty. Two kinds of objective criteria were used in the determination of patency. First, the treated artery segment was considered patent if the resting ABI had increased by more than 0.10 initially and not deteriorated by more than 0.15 from the maximum early postprocedural level (the criteria of Rutherford and ~ e c k e r )Unless . otherwise mentioned, the objective success and failure in this report refer to these criteria. Second, the treated artery segment was considered patent if the resting ABI was consistently a t least 0.15 above the preprocedural level (6).When the patency rate was calculated with subjective criteria, the treatments that were successes according to objective ABI criteria were considered subjective successes. Also, the treatments that were failures according to objective ABI criteria were considered subjec-
tive successes if they were classified by the patient in the categories "marked improvement" or "improvement." If the results were classified by the patient in the categories "no change," "mild worsening," or "marked worsening" they were considered to be subjective failures. Follow-up angiography was performed when new invasive treatment was needed based on the clinical situation of the patient. The cumulative patency rate versus time of follow-up for the 140 treated limbs was calculated with the KaplanMeier method. The statistical difference between survival curves was determined by means of the log-rank (Mantel-Cox) test. The primary patency rate was based on the results of the original PTA. In calculations of the secondary patency rate, results of repeated PTA procedures were also included. In patients requiring surgical interventions, treatments were regarded as failures. Survival curves were generated both by including and excluding the initial failures in the analysis. The Pearson x2 test for discrete variables and univariate logistic regression analysis for continuous variables were applied to identify the determinants of subjective patency. P c .05 was considered the level of statistical significance.
RESULTS The hemodynamic success rate for all 140 treated limbs was 89%; 99% for femoropopliteal dilations
Matsi and Manninen
161
Volume 6 Number 2
% Patency rate
% Patency rate
om
1
l
0
O
I
0
Months
Months
2. Figures 1,2. (1)Results of survival analysis (Kaplan-Meiermethod) for the primary and secondary patency rates for all 140 treated limbs according to the different criteria used (see Table). Initial failures included. (2) Results of survival analysis (Kaplan-Meiermethod) for the primary and secondary patency rates according to the different criteria used (see Table) and excluding initial failures. Life-table data are available on request. 1.
and 80% for femoropopliteal recanalizations (7). The cumulative primary and secondary patencies versus time of follow-up according to the different criteria used and including/excluding initial failures are shown in the Table and Figures 1 and 2. Statistically, there were no significant differences among patency rates obtained with the three criteria, but when the ABI criteria proposed by Rutherford and Becker were compared with subjective criteria, the difference in survival curves nearly reached statistical significance (P= .06). Primary patency rates differed significantly (all P = .01) from secondary patency rates when any of the criteria were applied, whereas inclusion or exclusion of initial failures did not result in significant differences between survival curves (P = .14-.19) By far, the best long-term results were obtained by applying patients' subjective selfevaluation of outcome. By using the
objective ABI criteria, the results were identical except for three cases of femoropopliteal recanalizations in which the criteria of Rutherford and Becker showed restenosis, while the other objective criteria showed patency. All three patients were subjective successes according to the criteria used. With the criteria of Rutherford and Becker, primary patency was lost during the follow-up period in 59 of the 140 treated limbs. In 36 of these 59 legs, restenosis (stenosis of at least 50% of normal diameter) was also angiographically verified and three patients who had undergone repeated angiography (failed PTAs according to the criterion of the ABI) showed development of a new lesion, while there was no restenosis a t the angioplasty site. PTA procedures in 24 of the 59 limbs (41%)were not failures with subjective criteria (13 classified as marked improvement and 11as improve-
ment by the patients). Among all patients whose primary treatment was successful, those who were subjective successes according to the criteria used at the end of follow-up had statistically significantly higher ABI values than those who were not (mean, 0.82 vs 0.60, respectively; P < .01). There were no significant differences between the ABI values of those patients with subjective success but objective failure and the patients with both subjective and objective failures. Among the patients with objective failures, those with subjective successes had slightly, though not statistically significantly, better runoff (when dichotomized as two to three Ygood runoffl vs zero or one ["poor" runoffl patent calf vessels) than those with subjective failures: 16 of 24 (67%)had good runoff in the former group versus 15 of 35 (43%) in the latter group (P = .07). There were no significant differences between the other tested variables: severity of the treated lesion (stenosis vs occlusion), severity of claudication (Fontaine IIA vs IIB), extensiveness of atherosclerotic disease in the treated limb (number of vessels with occlusions or stenosis over 50%), gender or age of the patient, or prevalence of diabetes. PTA procedures in five patients were objective successes but subjective failures. Further clinical and radiologic examinations revealed that besides claudication caused by atherosclerotic lower limb disease, two of them had spinal stenosis, one suffered from syndroma ischiadicum, and one had knee arthrosis. One patient was not known to have any other medical explanation for his symptoms.
DISCUSSION PTA was first introduced in 1964 and becamk an accepted technique in the mid-1970s when balloon catheters were developed. Since then it has gained broad acceptance in clinical practice. However, the greater
162
Journal of Vascular and Interventional Radiology
March-April 1995
than 30% range of differences in reported outcomes of both iliac and femoropopliteal balloon angioplasty have made the literature on this subject quite confusing (1,2). Variations in long-term results can be partly due to differences in patient selection but are without doubt partly due to the lack of uniform and objective criteria for defining successful outcome. SCVIWJVlR have recently adopted objective criteria (proposed by Rutherford and Becker) for evaluating and reporting the results of percutaneous therapy for peripheral arterial disease. According to these criteria ABI is one of objective means for determining patency. With ABI measurements, patency is determined by a consistent rise in the ABI (an increase of more than 0.10, and a less than 0.15 decrease below the early postprocedural maximum). By these standards initial failures must be included in the analysis, and primary and secondary patencies are clearly differentiated. Although ABI is an objective criteria for patency it does not help distinguish restenosis from a new lesion. In our work, 66% of restenoses according to ABI criteria were also angiographically verified and in 8% of cases, the reason for failure was a new lesion while the PTA-treated artery segment was widely patent. The increase in ABI after PTA can be minimal in cases of severe infrapopliteal disease, and on the other hand it can give erroneously high values in patients with calcified distal runoff vessels. However, its noninvasiveness and wide availability favor its use in routine clinical practice. Using the Rutherford criteria, we obtained primary patency rates of 47% a t 1year and 42% a t 2 and 3 years, which are seemingly low with respect to those reported by others (4,8-11). As far as we know, these strict objective ABI criteria have not been used as the sole determinant of outcome by other groups; other criteria, such as Doppler frequency analysis, treadmill exercise test, and subjective improvement, have been
utilized additionally in outcome evaluation (8-12). Further, we had a large number of patients with longsegment disease with a higher restenosis rate (7). In addition to using the ABI criteria of Rutherford and Becker, we also performed separate calculations applying ABI criteria proposed in the most recent recommendation of Ahn et al, in which the ABI must remain consistently a t least 0.15 above the preprocedural level to indicate patency (6). This produced long-term results that were only slightly better than those based on the criteria of Rutherford and Becker, however (Table). There was no difference in primary patency rate with use of either criteria when the treated femoropopliteal lesion was a stenosis. The difference was due to three cases of femoropopliteal recanalizations, in which ABI decreased more than 0.15 below the early postprocedural maximum but remained still a t least 0.15 above the preprocedural level. By far the best outcome figures were achieved by using the patients' subjective self-evaluation as the criteria for primary patency: 59% a t 1year and 56% at 2 and 3 years. If initial failures (15 of 140 limbs) are excluded, the 3-year primary patency rate is 5%-7% higher in this patient population, but in a population consisting solely of recanalizations with more initial failures, the difference would be greater. If initial failures are excluded, the reported results of angioplasty are based on the subset of patients with good initial technical outcome. This kind of data becomes less useful as a tool for predicting the potential benefit of PTA compared with surgical procedures. The secondary patency rate is useful in comparison of different kinds of vascular interventions, because it reflects the ultimate success that can be achieved. With the criteria of Rutherford and Becker the secondary patency rate was 59% at 3 years, and with subjective criteria it was 73% a t 3 years. Excluding initial failures, the secondary patency
rates a t 3 years were 66% and 82%, respectively. So, there is a range as great as 40% (42%-82%) in achieved patency rates a t 3 years in our patient population, depending on the outcome criteria used (Table). It is evident that conclusions based on the results of PTA, concerning for instance the clinical utility of this therapy, may be totally contradictory depending on how the results are reported. To find factors influencing subjective satisfaction, the subgroup of patients with objective failure but subjective success was compared with those with both objective and subjective failure. As many as 24 of 59 patients (41%)with objective failure reported subjective improvement in their symptoms a t the time of objective failure and did not require additional invasive treatment. Subjective satisfaction was slightly, though not statistically significantly, associated with good peripheral runoff. The association can be due to the ability of patients with good runoff to form sufficient collaterals to be able to benefit from exercise therapy. It is known that for the majority of patients with claudication, improvement in walking distance and subjective satisfaction can be achieved with a simple exercise program (13). One can assume that in critical ischemia the meaning of different criteria is not as great, because treatment failures lead more easily to bypass operations or amputations (14). On the other hand, in claudicants the long-term risk for amputation is low (15). It would be ideal if we could recognize those claudicants who will develop critical ischemia and perhaps prevent or a t least delay this event by means of PTA. It is useful to realize that controversies in PTA results depending on the criteria used are not important for the patient with claudication for whom subjective improvement is the most essential factor. On the other hand, subjective failures after angioplasty can be due to other than atherosclerotic lower limb disease, as was
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found in four patients in our study. The range of 42%-82%of achieved patency rates at 3 years in our patient population stresses the importance of uniform criteria when angioplasty results are reported. Our work shows that there is a minimal difference in patency rates with use of the ABI criteria of either Rutherford and Becker or Ahn et al. Articles published using one or the other criteria can still be compared quite well. Applying solely subjective improvement as a patency criterion gives erroneously high patency rates compared with objective criteria and makes comparison of different kind of therapeutic interventions unreliable. References 1. Rutherford RB, Becker GJ. Standards for evaluating and reporting the results of surgical and percutaneous therapy for peripheral arterial disease. JVIR 1991; 2:169-174. 2. Rutherford RB. Standards for evaluating results of interventional therapy for peripheral vascular disease. Circulation 1991; 83(supplI):I6-1-11.
3. Becker GJ, Katzen BT, Dake MD. Noncoronary angioplasty. Radiology 1989; 170:921-940. 4. Capek P, McLean GK, Berkowitz HD. femoropopliteal angioplasty, factors influencing long-term success. Circulation 1991; 83(suppl 1):I70-1-80. 5. Johnston KW. Femoral and popliteal arteries: reanalysis of results of balloon angioplasty. Radiology 1992; 183:767-771. 6. Ahn SS, Rutherford RB, Becker GJ, et al. Reporting standards for lower extremity arterial endovascular procedures. J Vasc Surg 1993; 17:1103-1107. 7. Matsi PJ, Manninen HI, Vanninen RL, et al. Femoropopliteal angioplasty in patients with claudication: primary and secondary patencies in 140 limbs with 1-3-year follow-up. Radiology 1994; 191:727-733. 8. Gallino A, Mahler F, Probst P, Nachbur B. Percutaneous transluminal angioplasty of the arteries of the lower limbs: a 5-year follow-up. Circulation 1984; 70:619-623. 9. Hewes RC, White RI Jr, Murray RR, et al. Long-term results of superficial femoral artery angioplasty. AJR 1986; 146:1025-1029. 10. Murray RR Jr, Hewes RC, White RI, et al. Long-segment femoro-
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