Objective assessment of coronary angioplasty for multivessel disease: results of exercise stress testing

Percutaneous transluminal coronary angioplasty versus medical therapy for stable angina pectoris: outcomes for patients with double-vessel versus single-vessel coronary artery disease in a Veterans Affairs Cooperative randomized trial. Veterans Affairs ACME InvestigatorS

OBJECTIVES

This study sought to assess outcomes of men with double-vessel coronary artery disease randomly assigned to treatment by percutaneous transluminal coronary angioplasty (PTCA) or medical therapy, compared with previously reported outcomes for men with single-vessel disease.

BACKGROUND

We previously reported that PTCA provides better symptom relief and treadmill performance than medical therapy for men with stable angina pectoris due to single-vessel disease. Whether this advantage applies to patients with double-vessel disease is unknown.

METHODS

Male patients (n = 328) with stable angina pectoris and ischemia on treadmill testing were randomly assigned to PTCA or medical therapy; 101 patients had double-vessel disease, and 227 had single-vessel disease. Symptoms, treadmill performance, quality of life score, coronary stenosis and myocardial perfusion were compared at baseline and at 6 months. Patients were followed up for up to 6 years and underwent additional treadmill testing 2 to 3 years after randomization.

RESULTS

PTCA-treated and medically treated patients with double-vessel disease experienced comparable improvement in exercise duration (+1.2 vs. +1.3 min, respectively, p = 0.89), freedom from angina (53% and 36%, respectively, p = 0.09) and improvement of overall quality of life score (+1.3 vs. +4.4, respectively, p = 0.32) at 6 months compared with baseline. This contrasts with greater advantages favoring PTCA by these criteria in patients with single-vessel disease (p = 0.0001 to 0.02). Trends present at 6 months persisted at late follow-up. Patients undergoing double-vessel dilation had less complete initial revascularization (45% vs. 83%) and greater average stenosis of worst lesions at 6 months (74% vs. 56%). Likewise, patients with double-vessel disease showed less improved myocardial perfusion imaging (59% vs. 75%).

CONCLUSIONS

PTCA is beneficial in male patients with double-vessel disease; however, we cannot demonstrate the same advantage over medical therapy seen in similar patients with single-vessel disease. Less complete revascularization and greater restenosis for patients having multiple dilations would account for these findings. Alternatively, a type 2 error might be operative. Technical advances since completion of this trial might improve these outcomes. These findings warrant further investigation in a larger trial.

The importance of completeness of revascularization during long-term follow-up after coronary artery operations

Completeness of revascularization after coronary artery bypass operation has been shown to improve short- and medium-term outcome. The purpose of this study was to assess the independent contribution of completeness of revascularization to long-term outcome. A total of 2057 patients with multivessel disease with complete revascularization and 803 with incomplete revascularization, mean age 57 +/- 9 years, was studied. The patient groups were similar except for more prior myocardial infarctions, worse left ventricular function, and more three-vessel disease in the incomplete revascularization group. Complications of perioperative infarction and stroke were not different between those having complete versus incomplete revascularization. The hospital death rate for patients having complete revascularization during the period of study was 0.7% versus 1.5% for those having incomplete revascularization (p = 0.06). Length of hospital stay for the two groups of patients also was not different. At late follow-up (mean 11.7 years for complete and 10.8 years for incomplete) patients who had incomplete revascularization had a significantly higher prevalence of recurrent angina. Multivariate analysis demonstrated the strongest predictors of incomplete revascularization to be number of vessels diseased and left ventricular function (ejection fraction). The multivariate correlates of survival were older age, left ventricular dysfunction, and completeness of revascularization. Completeness of revascularization correlated with improved overall patient survival, as well as survival in patients with normal left ventricular function. Furthermore, the curves continued to separate over time, such that the difference was greater at 8 years than at 4 years, although by 12 years the curves started to converge.

The value of exercise electrocardiography testing in the identification of coronary restenosis: a probability analysis

We studied by means of probability analysis the role of exercise ECG in identifying coronary restenosis. A total of 213 patients were independently evaluated by clinical history, conventional assessment of the exercise ECG ('yes or no' statement), D score (a discriminant function derived from exercise ECG), and coronariography, 5.4 +/- 2.8 months after successful coronary angioplasty. The initial probability of restenosis (30%), that is, the prevalence of the condition, was radically changed by the result of clinical history (77% for patients with angina vs. 17% for those without angina). By contrast, ECG binary assessment, due to its low accuracy (70% vs 82% of clinical history, P < 0.005), was unable to significantly change the established probabilities after symptomatic evaluation. Finally, D score, which greatly enhanced specificity (92% vs. 76% of bivariate assessment, P < 0.0001), proved to be useful in changing the probability (from 32% to 76% or to 25%) of patients (n = 34) with a discordant result (no angina/positive exercise ECG). When this stepwise approach was tested in 46 new patients, predicted and observed probabilities were actually very similar. We conclude that exercise ECG has a very limited role in identifying coronary restenosis if positive responses are not adjusted with a weighted score which takes into account other exercise derived factors.

Value and limitations of exercise stress testing to predict the functional results of coronary artery bypass grafting

To assess the value of exercise stress testing to predict the functional result of revascularization, 90 patients were evaluated by coronary angiography and exercise testing pre and postoperatively. Patients were classified on the basis of the postoperative angiogram in a group with successful surgery and a group with unsuccessful surgery. The predictive accuracy positive of ST segment depression to detect unsuccessful surgery was 67% The predictive accuracy negative was 61%. The best predictor of unsuccessful surgery was residual angina pectoris after revascularization with predictive value positive and negative of 85% and 60%, respectively. Thus exercise stress testing has limited value to accurately predict the degree of revascularization.

Pitfalls in the color Doppler diagnosis of valvular regurgitation

Color Doppler flow mapping of the regurgitant jet is frequently used as a means of assessing the severity of valvular regurgitation. Although convenient, this method of assessing valvular regurgitation is subject to a number of hemodynamic and technical factors that may limit its accuracy. Variations in hemodynamic and structural factors such as orifice size, jet geometry, receiving chamber constraints, afterload, fluid viscosity, heart rate, and cardiac output may have profound effects on the measured regurgitant jet area. Variations in scanning and machine factors, such as scanning direction, Doppler angle, frame rate, color display algorithms, pulse repetition frequency (PRF), system gain, packet size, carrier frequency, wall filter, and transmit power have been shown to alter the measured regurgitant jet area significantly. Despite these limitations, color flow Doppler provides a relatively reliable noninvasive method for semiquantitative assessment of valvular regurgitation. Obviously, standardization of the design and application of the various available color mapping algorithms, as well as other machine and hemodynamic factors, would help provide more reliable and reproducible quantitative information about the degree of valvular insufficiency.

Quantification of asymmetric valvular regurgitant jets by color Doppler ultrasound in vitro

Accurate quantification of regurgitant jets in natural and prosthetic heart valves has been a goal of health care workers and researchers for many years. One promising new method applies the law of conservation of momentum transfer to velocities measured by color Doppler ultrasound to calculate the flow rate in the jet. One complicating factor is that regurgitant jets from real heart valves may be highly asymmetric. The purpose of this investigation was to determine whether the accurate calculation of the flow rate in asymmetric jets imaged by color Doppler requires an asymmetric formulation of the conservation of momentum transfer, combined with a method for imaging the jet in three dimensions. Asymmetric jets issuing from narrow slits were imaged in an in vitro, steady flow system. The ultrasound transducer was rotated around the jet axis to image the jet in three dimensions. The three-dimensional imaging confirmed that jets from slits are indeed asymmetric, but become relatively axisymmetric far from the orifice. Images were analyzed by computer and the calculated flows compared to measured flows. The accuracy of an asymmetric formulation of the conservation of momentum transfer method was compared to a simpler, axisymmetric formulation. If axisymmetry was assumed in asymmetric jets, significant errors in the calculated flow rates occurred. In these cases, the calculated flow also varied widely with distance from the orifice. When asymmetry was taken into account, the errors were considerably reduced. The results suggest that, in asymmetric jets, the momentum transfer is convected around the jet axis.

Safety and clinical use of exercise testing one to three days after percutaneous transluminal coronary angioplasty

To evaluate both the safety and clinical use of predischarge symptom-limited exercise testing after successful uncomplicated percutaneous transluminal coronary angioplasty (PTCA), 100 patients were randomized to undergo exercise testing (n = 50) or no exercise testing (n = 50). There were no differences in clinical or angiographic characteristics between the groups. Exercise testing was performed 38 +/- 14 hours after PTCA. Patients who exercised achieved 71 +/- 12% of predicted maximal heart rate, with 38% reaching greater than or equal to stage III of the Bruce protocol. No patient in either group developed cardiac complications during 48-hour follow-up. Of the 11 patients with a positive test result, 92% had angiographically incomplete revascularization. Attending physicians (n = 16) were questioned both before and after exercise testing about when, after discharge, they would allow their patient to perform each of 11 specific activities of daily living. Questionnaires were administered to physicians at similar time frames for patients in the no-exercise group. Comparison of the responses between initial and repeat questionnaires showed that patients in the exercise group (with a test result negative for ischemia) were allowed to perform 7 of 11 activities, including return to work, earlier (p less than 0.05) than the no-exercise patients. These data indicate that in this well-defined group of patients, symptom-limited exercise testing early after PTCA appears to be safe, and alters physician management in allowing patients with a negative test result to return to various activities at an earlier date. Such testing may be useful in counseling patients after PTCA.

Transesophageal echocardiography

Transesophageal echocardiography has provided a new acoustic window to the heart, the great vessels, and the mediastinum. It provides anatomical, functional hemodynamic, and blood flow information. High-quality visualization of left atrial appendage, thoracic aorta, atrial septum, and mitral valvular apparatus can be obtained readily. We discuss historical and technical aspects of transesophageal echocardiography, anatomical views, and major clinical indications for this procedure. These indications include intracardiac masses, thoracic aortic dissection, endocarditis, prosthetic and native cardiac valve function assessment, as well as its value in the detection of intracardiac source of systemic emboli. Furthermore, the role of transesophageal echocardiography in the assessment of coronary artery and congenital heart disease and as an intraoperative diagnostic and monitoring technique is discussed.

PTCA in patients with stable angina pectoris and multivessel disease: is incomplete revascularization acceptable?

Of all coronary angioplasties performed nowadays, 40% of the patients have multivessel disease. Angioplasty in patients with multivessel disease can be performed with a high immediate clinical success rate and an acceptable major complication rate. However, complete anatomic revascularization with coronary angioplasty is achieved in only 32 to 59%. This raises concern about the immediate and long-term outcome of patients in whom incomplete revascularization is achieved. This report reviews the literature and provides evidence that incomplete revascularization with coronary angioplasty is a safe and effective treatment in selected patients with multivessel disease, provided that adequate (functional) revascularization can be achieved. Adequate revascularization includes dilation of all significant lesions supplying large areas of viable myocardium.

A comparison of angioplasty with medical therapy in the treatment of single-vessel coronary artery disease. Veterans Affairs ACME Investigators

BACKGROUND

Despite the widespread use of percutaneous transluminal coronary angioplasty (PTCA), only a few prospective trials have assessed its efficacy. We compared the effects of PTCA with those of medical therapy on angina and exercise tolerance in patients with stable single-vessel coronary artery disease.

METHODS

Patients with 70 to 99 percent stenosis of one epicardial coronary artery and with exercise-induced myocardial ischemia were randomly assigned either to undergo PTCA or to receive medical therapy and were evaluated monthly. The patients assigned to PTCA were urged to have repeat angioplasty if their symptoms suggested restenosis. After six months, all the patients had repeat exercise testing and coronary angiography.

RESULTS

A total of 107 patients were randomly assigned to medical therapy and 105 to PTCA. PTCA was clinically successful in 80 of the 100 patients who actually had the procedure, with an initial reduction in mean percent stenosis from 76 to 36 percent. Two patients in the PTCA group required emergency coronary-artery bypass surgery. By six months after the procedure, 16 patients had had repeat PTCA. Myocardial infarction occurred in five patients assigned to PTCA and in three patients assigned to medical therapy. At six months 64 percent of the patients in the PTCA group (61 of 96) were free of angina, as compared with 46 percent of the medically treated patients (47 of 102; P less than 0.01). The patients in the PTCA group were able to increase their total duration of exercise more than the medical patients (2.1 vs. 0.5 minutes, P less than 0.0001) and were able to exercise longer without angina on treadmill testing (P less than 0.01).

CONCLUSIONS

For patients with single-vessel coronary artery disease, PTCA offers earlier and more complete relief of angina than medical therapy and is associated with better performance on the exercise test. However, PTCA initially costs more than medical treatment and is associated with a higher frequency of complications.

Prognosis of culprit lesion PTCA in acute myocardial infarction for multi versus single vessel disease

We studied 417 patients undergoing single vessel culprit lesion percutaneous transluminal coronary angioplasty (PTCA) for acute myocardial infarction to determine the impact of disease in other vessels. Group A (189 patients, 45%) had coronary artery disease (greater than or equal to 70% stenosis) in at least 1 additional vessel while Group B (228 patients, 55%) did not. The groups were similar in sex distribution (A = 75% male, B = 76%), number of lesions in the single culprit vessel dilated (1 lesion in 83% A, 80% B), and PTCA success (A = 92%, B-94%) (all p = NS). Group A patients were older (63 +/- 10 vs. 56 +/- 11 years) and had more prior myocardial infarctions (27% vs. 7%), and more prior coronary artery bypass grafting (15% vs. 0.4%) (all p less than .01). Group A patients were more likely to have repeat catheterization (48% vs. 32%, p less than .005) although restenosis of the infarct-related vessel was similar (A = 24%, B = 16%) (p = NS). Group A was more likely to need angioplasty in a 2nd vessel (23% vs. 8%) and to need coronary artery bypass grafting (20% vs. 8%) (both p less than .001). Cumulative mortality was higher in Group A at 1 month (10% vs. 5%), 1 year (11% vs. 6%), and long-term (13% vs. 7%). This difference appeared to be due to the impact of lower mean ejection fraction in Group A.

CONCLUSION

Treatment of acute myocardial infarction by direct PTCA of the culprit lesion can be performed with a high likelihood of success in patients with or without multivessel coronary artery disease.(ABSTRACT TRUNCATED AT 250 WORDS)

Percutaneous transluminal coronary angioplasty of the left coronary artery in patients with chronic occlusion of the right coronary artery: clinical and functional results

The safety and therapeutic benefits of percutaneous transluminal coronary angioplasty of the left anterior descending coronary artery, the left circumflex coronary artery or both were assessed in 61 patients with chronic (greater than 3 months) occlusion of the right coronary artery. Recanalization of the right coronary artery was not performed before dilatation of left coronary artery lesions. All lesions could be dilated without an acute ischemic event in the catheterization laboratory. However, three patients underwent coronary artery bypass surgery within the first 8 days after coronary angioplasty. There were no in-hospital deaths. Of the remaining 58 patients, 51 (88%) had repeat angiography at a mean of 5.2 +/- 2.5 months. Patients were divided into two groups according to the presence (n = 17) or absence (n = 34) of restenosis defined as greater than or equal to 50% diameter stenosis at the dilated site. Baseline characteristics were comparable. The mean value for angina functional class at follow-up was significantly better in the group without than in the group with restenosis (0.4 +/- 0.6 vs 2.1 +/- 1.1, respectively; p less than 0.001). Sixty-five percent of the patients without restenosis were asymptomatic at follow-up. Seventy-five percent of the predicted maximal physical capacity was reached by 76% of the patients without restenosis compared with 33% in the group with restenosis (p less than 0.05).(ABSTRACT TRUNCATED AT 250 WORDS)

Multivessel coronary angioplasty from 1980 to 1989: procedural results and long-term outcome

From June 1980 to January 1989, 3,186 patients had coronary angioplasty of two (2,399 patients) or three (787 patients) of the three major epicardial coronary systems. A mean of 3.6 lesions (range 2 to 14) were dilated per patient, with a 96% success rate. Acute complications were seen in 94 patients (2.9%) and included Q wave infarction in 47 (1.4%), urgent coronary artery bypass surgery in 33 (1%) and death in 31 (1%). Multivariate correlates of in-hospital death included impaired left ventricular function, age greater than or equal to 70 years and female gender. Complete long-term follow-up data were available for the first 700 patients and the follow-up period averaged 54 +/- 15 months in duration. Actuarial 1 and 5 year survival rates were 97% and 88%, respectively, and were not different in patients with two or three vessel disease. By Cox regression analysis, age greater than or equal to 70 years, left ventricular ejection fraction less than or equal to 40% and prior coronary artery bypass surgery were associated with an increased mortality rate during the follow-up period. Repeat revascularization procedures were required in 322 patients (46%). Restenosis resulted in either repeat angioplasty or bypass surgery in 227 patients (32%). Repeat coronary angioplasty was performed for isolated restenosis in 126 patients (18%), for restenosis and disease progression at new sites in 85 patients (12%) and for new disease progression alone in 54 patients (8%). Coronary bypass surgery was required in 110 patients (16%) during the follow-up period.(ABSTRACT TRUNCATED AT 250 WORDS)

Successful multiple segment coronary angioplasty: effect of completeness of revascularization in single-vessel multilesions and multivessels

A long-term follow-up study was performed to evaluate the long-term value of performing multiple dilatations according to their procedural (single-vessel multilesion or mutltivessel dilatations) and anatomic types (single-vessel disease with multiple dilatations or multivessel disease dilatations with complete and incomplete revascularization). From 1980 until 1988, 248 patients met the following criteria: (1) at least two lesions dilated (range: 2 to 4) and (2) all attempted lesions successfully dilated. The mean length of follow-up was 33 months. The end points analyzed were death, myocardial infarction, redilatation, and bypass surgery. No differences were found for these events between the single-vessel multilesion group (144 patients) and the multivessel group (104 patients). The 4.5-year probability of event-free survival was 68% and 70%, respectively, for the multilesion group and the multivessel group. In the event-free patients, 57% versus 59% were asymptomatic and 45% versus 46% were not taking antianginal drugs. In the anatomic subgroups, there were less event-free patients in the cohort of incompletely revascularized multivessel disease patients (55% of 55 patients) when compared with the cohort of those who were completely revascularized (84% of 79 patients) or when compared with the single-vessel disease multiple dilatation patients (74% of 107 patients). The 4.5-year event-free survival probability for each group was 44%, 78%, and 74%, respectively. This difference was caused by more infarctions (9% versus 2% versus 4%, respectively) and bypass operations in the multivessel disease, incomplete revascularization group (20% versus 5% versus 10%, respectively). In event-free patients, improvement of angina was similar and was documented in over 85% of patients in each group. Furthermore, the number of asymptomatic patients at follow-up was similar in all groups except that within the incomplete revascularization group, less patients were free of antianginal drugs (21% versus 51% versus 48%). Finally, 48% of the entire cohort performed an exercise test 4.6 months (mean) after dilatation and no difference was found in any of the variables in any group. About 10% of the patients experienced angina and approximately 30% had a positive exercise test for ischemia by ST segment criteria. The functional performance in every group was over 90% of the predicted work load. These results suggest that completeness of revascularization in multivessel disease patients is an important prognostic variable. However, the symptomatic improvement after dilatation is very rewarding in all subsets of patients and argues in favor of the continued use of multiple dilatations as a treatment strategy.

PTCA of the left coronary artery when the right coronary artery is chronically occluded

Angioplasty of the left coronary artery was undertaken in 65 patients with a chronic total occlusion of the right coronary artery (CLOSED RCA) and in 105 patients with no significant disease in the right coronary artery (OPEN RCA). No patient had attempted dilatation of the right coronary artery. CLOSED RCA versus OPEN RCA patients differed with respect to presence of poor left ventricular (LV) function (12% versus 4%, p = 0.07), number of stenoses per patient (2.2 versus 1.8, p less than 0.05), and stenoses in both left anterior descending and left circumflex artery (39% versus 23%, p less than 0.05). Procedural complications were low for both CLOSED RCA (one death) and OPEN RCA (one emergency bypass surgery) patients. At late follow-up (mean = 17 months), there was no difference in survival between CLOSED RCA and OPEN RCA patients (95% versus 93%, p = NS). Late cardiac events (death, bypass surgery, or myocardial infarction) occurred in 26% of CLOSED RCA patients and in 16% of OPEN RCA patients (p = ns). The absence of angina at follow-up was more frequent in OPEN RCA compared with CLOSED RCA patients (84% versus 61%, p less than 0.01). Angioplasty of the left coronary artery can be performed in CLOSED RCA patients without excessive procedural risk; however, at follow-up continued anginal symptoms are common.

The effect of complete and incomplete revascularization on exercise variables in patients undergoing coronary angioplasty

To investigate the effects of complete and incomplete revascularization on the response to exercise, 25 patients underwent symptom-limited exercise testing with continuous assessment of gas exchange a mean of 5 +/- 4 days prior to and 18 +/- 12 days following percutaneous transluminal coronary angioplasty. All antianginal medications were discontinued for testing. Revascularization was considered complete if all stenoses were reduced to less than 50% diameter (13 patients), and incomplete if one or more stenoses remained (12 patients). Consistent improvements in ST-segment depression were observed after angioplasty at matched submaximal exercise levels (mean range 0.5-0.8 mm; p less than 0.05), and were accompanied by a reduction in angina. Significant increases in heart rate and systolic blood pressure were observed at peak exercise following angioplasty in both groups. Gas exchange variables were significantly improved at maximal exercise, with a similar increase in oxygen uptake observed in both groups following angioplasty (mean increase 3.3-3.7 ml/kg/min; p less than 0.01). Thus, incomplete revascularization following coronary angioplasty resulted in hemodynamic, electrocardiographic, symptomatic, and gas exchange responses to exercise that were comparable to complete revascularization.

Augmented myocardial perfusion reserve after coronary angioplasty quantified by positron emission tomography with H2(15)O

Effects of coronary angioplasty on myocardial flow reserve have been difficult to characterize noninvasively because conventional imaging techniques cannot quantitate blood flow in absolute terms. The effects of coronary angioplasty on myocardial perfusion and perfusion reserve were delineated with positron emission tomography and oxygen-15-labeled water (H2(15)O) in 13 patients before and after single vessel angioplasty. In 11 patients, angioplasty was successful (minimal cross-sectional area increased from 0.60 +/- 0.59 to 3.45 +/- 1.09 mm2, p less than 0.001). In these patients, regional H2(15)O radioactivity (the ratio of nutritional perfusion in regions distal to the stenosis compared with regions supplied by angiographically normal arteries) at rest before angioplasty was 55 +/- 22% of peak myocardial radioactivity and did not increase significantly afterward (70 +/- 16%, p = NS). However, after administration of intravenous dipyridamole, hyperemic perfusion in regions distal to a stenosis averaged only 39 +/- 18% of peak myocardial counts before angioplasty, but increased to 66 +/- 22% after angioplasty (p less than 0.02). Perfusion reserve in the two patients in whom angioplasty was angiographically unsuccessful showed no change. Quantitative estimates of perfusion in absolute rather than relative terms were obtained with positron emission tomographic data from seven of the patients with successful angioplasty. At rest, perfusion in regions distal to a stenosis was not different from the values in regions supplied by normal coronary arteries (1.54 +/- 0.54 compared with 1.46 +/- 0.38 ml/g per min, p = NS).(ABSTRACT TRUNCATED AT 250 WORDS)

Prognostic value of early exercise stress testing after successful coronary angioplasty: importance of the degree of revascularization

The prognostic value of early exercise testing after successful coronary angioplasty was determined in 196 and 225 consecutive patients with single-vessel and multivessel coronary disease, respectively, who underwent a symptom-limited exercise test within 30 days of the procedure. The incidence of exercise-induced ST segment depression greater than or equal to 1 mm was significantly greater in patients with multivessel versus single-vessel disease (27% versus 14%; p less than 0.005) and in patients with multivessel coronary disease who had incomplete versus complete revascularization (36% versus 10%; p less than 0.001). An abnormal exercise ECG result was associated with a significantly increased risk of cardiac events in patients with multivessel disease but not in patients with single-vessel disease. Exercise-induced angina occurred in a small and similar proportion of patients with single and multivessel coronary disease (8% versus 12%). The presence of exercise-induced angina was associated with a higher incidence of follow-up cardiac events in patients with multivessel disease and incomplete revascularization (52% versus 33%; p less than 0.05). Exercise duration was significantly less in patients with multivessel disease who had a subsequent cardiac event compared with that in patients who did not have such an event (458 +/- 168 versus 519 +/- 156 seconds; p = 0.01). Thus an abnormal exercise ECG finding within 1 month of successful coronary angioplasty is predictive of subsequent cardiac events in patients who have multivessel disease. The prognostic content of the test might be further improved if the test were performed several months after the procedure when the risk of restenosis is greatest.