Effect of Percutaneous TransluminalCoronary Angioplasty on Exercise inPatients With and Without Previous

Myocardial InfarctionBjørn Jørgensen, MD, Svein Simonsen, MD, PhD, Kolbjørn Forfang, MD, PhD,

Knut Endresen, MD, PhD, and Erik Thaulow, MD, PhD

Improvement in exercise capacity is an important clinicaleffect of percutaneous transluminal coronary angio-plasty (PTCA), and was assessed in patients with andwithout previous myocardial infarction (MI) undergoingPTCA. We prospectively followed patients with exercisetesting before and 2 weeks after angioplasty in 415patients, 170 (41%) of whom had a previous MI. A thirdexercise test was performed 20 6 2 weeks after PTCA in403 patients. From left ventricular angiography ob-tained before PTCA, regional dyskinesia was classifiedinto anterior or posterior locations. Both patients withand without previous MI had a significant increase inexercise capacity from before to 2 and 20 weeks afterPTCA (previous MI: 31.9% and 29.3%; no MI: 50.7%and 38.2%; p <0.0001 [analysis of variance]). In pa-tients with MI and anterior dyskinesia, in whom lesions

on the left anterior descending artery were dilated orposterior dyskinesia in whom lesions on the right coro-nary artery were dilated, exercise capacity increasedsignificantly from before to 2 and 20 weeks after PTCA(left anterior descending artery: 53.1% and 39.7%, p<0.0001; right coronary artery: 16.9% and 27.6%, p 50.01 [analysis of variance]). Multivariate regressionanalysis revealed that male sex, no previous MI, anddilation of left anterior descending artery were signifi-cantly associated with increased exercise capacity afterangioplasty adjusted for age and smoking habits,whereas left ventricular ejection fraction and end-dia-stolic pressure were not associated with increased exer-cise capacity. Q1998 by Excerpta Medica, Inc.

(Am J Cardiol 1998;82:1030–1033)

C linical improvement with reinforcement of exer-cise capacity can be quantified by exercise testing,

and is well documented in patients undergoing angio-plasty.1–4 Myocardial infarction (MI) injures the myo-cardium and may reduce left ventricular function.Amelioration of both normal and dyskinetic left ven-tricular function has been demonstrated after revascu-larization.3,5–9 Nevertheless, it remains to be shownwhether improvement of regional myocardial bloodsupply by angioplasty gives rise to an increase inexercise capacity in patients with previous MI, andalso if an increase in exercise capacity is achievablefor patients with dyskinetic myocardial regions andprevious MI. This study investigates the improvementin exercise capacity with respect to patients with dys-kinetic left ventricles and previous MI compared withpatients without MI, and evaluates the predictivevalue of left ventricular ejection fraction and end-diastolic pressure on change in exercise capacity afterangioplasty.

METHODSPatients: From 1992 to 1996, patients included in

the Coronary AngioPlasty Amlodipine REstenosisStudy (CAPARES),10 which was designed to studythe effect of the calcium channel antagonist amlodip-

ine on restenosis after PTCA, underwent exercise test-ing before and after PTCA. Inclusion criteria werestable angina pectoris, age,70 years, no previouscoronary intervention, coronary artery stenosis suit-able for PTCA, and satisfactory angiographic post-PTCA result without major in-hospital complications.A total of 415 consecutive patients underwent exercisetesting 2 weeks before and 2 weeks after successfulangioplasty, and made up the main study population.A third exercise test was performed after 20 weeks inconnection with an angiographic follow-up in 403patients. The diagnosis of previous MI was based onmedical history and hospital records, documentingeither creatine kinase levels.2 SDs from normalmean value, or presence of abnormal Q-waves on theelectrocardiogram. Beta-blocker medication was con-tinued throughout the study to avoid influence onexercise test performance by withdrawal. The studymedication was started after the first exercise test, andhad no impact on exercise capacity after PTCA. Allpatients gave written informed consent to the studyand approved by the local ethics committee.

Exercise test: The exercise tests were performed inthe upright position, on a computer-controlled (Sie-mens Megacart, Siemens-Elema AB, Solna, Sweden),electrically braked ergometer bicycle. The startingload was 50 W (2.94 kJ/min) and was increased step-wise by 50 W every sixth minute. The patients wereencouraged to continue the exercise test until exhaus-tion. The test was discontinued earlier if 1 of thefollowing events occurred: increasing angina, severe

From the Department of Cardiology, Rikshospitalet, University of Oslo,Oslo, Norway. Manuscript received February 10, 1998; revisedmanuscript received and accepted June 4, 1998.

Address for reprints: Bjørn Jørgensen, MD, Kardiologisk seksjon,Medisinsk avdeling B., Rikshospitalet, N-0027 Oslo, Norway.

1030 ©1998 by Excerpta Medica, Inc. 0002-9149/98/$19.00All rights reserved. PII S0002-9149(98)00549-9

dyspnea, sudden dizziness, headache or nausea,.3couplet ventricular beats, atrial fibrillation or flutter, adrop in systolic blood pressure by.20 mm Hg, or anincrease in systolic blood pressure.300 mm Hg.Exercise capacity was defined as the cumulated workperformed (workload in watts times duration of exer-cise in minutes) divided by the body weight (W3min/kg).11

Coronary angiography, angioplasty, and left ventric-ular analysis: Angioplasty was performed according tostandard clinical practice by the femoral approach.Complete revascularization was defined as a success-ful angioplasty and no other diameter stenosis$50%in the major coronary arteries not treated with PTCA.Identical angiographic views were taken immediatelybefore and after PTCA, and at follow-up. Left ven-tricular angiograms were obtained in the 30° rightanterior oblique projection. Left ventricular ejectionfraction was calculated by the area-length method, andend-diastolic pressure was measured by an intraven-tricular saline-filled catheter connected to an externalpressure transducer. All angiograms were analyzed bythe Cardiovascular Angiography Analysis System (PieMedical Imaging, Maastricht, Netherlands), and quan-titative analysis was carried out as described earlier bySerruys et al.12

Statistical analysis: Continuous variables are ex-pressed as means6 SD. Differences between meanswere tested with a 2-tailed Student’st test. Compari-son of the 3 exercise tests was performed using anal-ysis of variance. The Mann-Whitney U test was usedto compare groups with variables showing skeweddistributions. Categorical variables are expressed ascounts and percentages, and were compared usingFisher’s exact test. From an exploratory correlationmatrix, variables correlated with change in exercisecapacity were incorporated in a multivariate linearregression model and left ventricular ejection fractionand end-diastolic pressure were added to the model ascovariates, with change in exercise capacity from be-fore to after PTCA as the dependent variable. Thelevel of significance was set at 0.05.

RESULTSThe clinical and angiographic baseline variables

are shown in Table I. Patients with previous MI weresignificantly younger and had a lower left ventricularejection fraction than the patients without MI. Signif-icantly more patients in the MI group were on angio-tensin-converting enzyme inhibitors, but this did notaffect the results. Angioplasty on either the left ante-rior descending artery alone, or in combination withthe left circumflex artery and/or the right coronaryartery was performed more frequently among patientswithout previous MI. The mean change in minimalluminal diameter from before angioplasty to immedi-ately after angioplasty (early gain), and from beforeangioplasty to 20 weeks follow-up angiography (netgain) were equal in the patients with previous MI andin those without (0.936 0.47 mm vs 0.936 0.46 mmand 0.696 0.49 mm vs 0.626 0.58 mm). The resultsfrom the 3 exercise tests are shown in Table II. Exer-

cise capacity before PTCA was the same in patientswith and without MI, and all groups had a significantincrease in exercise capacity after PTCA. Men with-out MI had a significantly higher increase in exercisecapacity from before to 2 weeks after PTCA comparedwith men with previous MI (9.16 8.3 W 3 min/kg[53%] vs 5.86 7.1 W 3 min/kg [33%], p,0.001).The most marked increase in exercise capacity(10.0 6 8.7 W 3 min/kg [57%]) was seen in menwithout MI when angioplasty involved the left ante-rior descending artery. In patients with MI and adyskinetic left ventricle, exercise capacity increasedsignificantly from before to 2 and 20 weeks afterPTCA when angioplasty was performed on the leftanterior descending artery in patients with anterior leftventricular dyskinesia, and also when angioplasty wasperformed on the right coronary artery in patients withposterior left ventricular dyskinesia (Table III). Mul-tivariate regression analysis revealed that neither theleft ventricular ejection fraction nor end-diastolicpressure were associated with change in exercise ca-pacity (Table IV).

DISCUSSIONImprovement of left ventricular function after re-

vascularization has been shown both at rest and duringexercise in several studies using various imaging tech-niques,3,5–9,19,20and this improvement may cause an

TABLE I Baseline Clinical and Angiographic Characteristicsof Patients With and Without Previous Myocardial Infarction

CharacteristicNoninfarction

(n 5 245)Infarction(n 5 170)

Age (yrs) 56 6 8 54 6 9*Body mass index (kg/m2) 26 6 3 26 6 3Smoker 58 (23.7) 39 (22.9)Diabetes mellitus 13 (5.3) 9 (5.3)Systemic hypertension 57 (23.3) 40 (23.5)Angina status (CCS)

I 37 (15.4) 24 (15.0)II 111 (46.1) 85 (53.1)III–IV 93 (38.6) 51 (31.9)

Medicationb blocker 218 (90.1) 158 (92.9)

Calcium antagonist 129 (52.7) 82 (48.2)Angiotensin-convertingenzyme inhibitor

14 (5.7) 28 (16.5)*

End-diastolic pressure(mm Hg)

15.6 6 5.9 16.3 6 5.8

Ejection fraction (%) 77.3 6 7.2 68.7 6 12.2*No. of coronary arteriesnarrowed .50% indiameter:1 161 (65.7) 85 (50.0)*2 75 (30.6) 68 (40.0)3 9 (3.7) 17 (10.0)*

LAD involvement† 168 (68.6) 99 (58.2)*Stents implanted 33 (13.5) 28 (16.5)Completerevascularization

154 (63.6) 99 (59.3)

Values are means 6 SD, and numbers (percentages).*p ,0.05 compared with noninfarction.†Dilation of left descending artery (LAD) alone or in combination with left

circumflex artery and/or right coronary artery.CCS 5 Canadian Cardiovascular Society.

CORONARY ARTERY DISEASE/EXERCISE CAPACITY IMPROVEMENT AFTER ANGIOPLASTY 1031

increase in exercise capacity measured by exercisetesting.

The main purpose of this study was to investigatethe impact of angioplasty on exercise capacity inpatients with and without previous MI. In addition, thequestion arose of whether angioplasty was profitablein patients with previous MI when angioplasty wasperformed in vessels supplying dyskinetic myocardialregions.

In agreement with others,1,13–15

this study demonstrated that exercisecapacity increased after PTCA. Bystratifying the patients into thosewith and without previous MI, theincrease in exercise capacity afterPTCA was significant in bothgroups, although more pronouncedin the patients without MI. Kent etal5 demonstrated a significant in-crease in ejection fraction from 51%at rest to 62% during exercise afterPTCA, in contrast to no increase dur-ing exercise before PTCA. Perry etal6 also showed a significant increasein ejection fraction during exerciseafter PTCA in patients with no pre-vious MI (11%), and in patients withprevious MI (13%), whereas theejection fraction fell significantlyduring exercise before PTCA. Thesefindings agree with the improvementin exercise capacity seen in ourstudy. Linderer et al16 clearly dem-onstrated that in patients with latePTCA after acute MI (56 6 monthsafter MI), the left ventricular ejectionfraction increased significantly afterPTCA, especially in the patients witha left ventricular ejection fraction,60%. This is in context with otherstudies, which show that revascular-ization of hibernating viable myocar-dium restores impaired left ventricu-

lar function.7,8,17,18Regional left ventricular dyskine-sia caused by ischemic hibernating myocardium mayexplain why the left ventricular ejection fraction andend-diastolic pressure before angioplasty did not pre-dict the improvement in exercise capacity seen afterangioplasty in our study. The higher increase in exer-cise capaity seen in the patients who had PTCA on theleft anterior descending artery is most probably relatedto that a larger myocardial area at risk is involved,compared with the other coronary arteries.19,20

In patients with previous MI and also in whomangioplasty was performed in vessels supporting dys-kinetic myocardium, significant improvement in exer-cise capacity after PTCA was found, indicating im-portant functional benefit in these patients as well.

Study limitations: The patients with MI weregrouped on the basis of history only, with the risk ofimplementing patients with undetected MI in thenon-MI group. We did not perform left ventricularangiography after angioplasty, which would have pro-vided us with comparable information regarding im-provement of left ventricular function after revascu-larization.

1. Berger E, Williams DO, Reinert S, Most A. Sustained efficacy of percutaneoustransluminal coronary angioplasty.Am Heart J1986;111:233–236.2. Cowley MJ, Vetrovec GW, Wolfgang TC. Efficacy of percutaneous translu-

TABLE II Exercise Capacity (EC) (W 3 minutes 3 kg21) Before and AfterAngioplasty Stratified by Sex in the Noninfarction and Infarction Groups

EC BeforeAngioplasty

EC 2 wks AfterAngioplasty

EC 20 wks AfterAngioplasty p Value*

Patients without MI(n 5 245)

15 6 10 23 6 11 22 6 13 ,0.0001

Patients with previous MI(n 5 170)

16 6 10 22 6 10 21 6 11 ,0.0001

Women without MI(n 5 50)

9 6 6 11 6 6 11 6 6 0.0006

Women with previous MI(n 5 25)

9 6 6 11 6 6 11 6 5 0.002

Men without MI(n 5 195)

17 6 10 26 6 10 25 6 12 ,0.0001

Men with previous MI(n 5 145)

18 6 10 24 6 10 23 6 11 ,0.0001

Values are mean 6 SD.*Exercise tests are compared using analysis of variance.

TABLE III Exercise Capacity (EC) (W 3 minutes 3 kg21) Before and AfterAngioplasty in Patients With MI and Left Ventricular Dyskinesia

EC BeforeAngioplasty

EC 2 wks AfterAngioplasty

EC 20 wks AfterAngioplasty p Value*

Left anterior descendingartery and anteriordyskinesia (n 5 33)

15 6 13 24 6 12 22 6 13 ,0.0001

Right coronary artery andposterior dyskinesia(n 5 15)

17 6 7 20 6 9 22.0 6 10 0.01

Values are mean 6 SD.*Exercise tests are compared using analysis of variance.

TABLE IV Results from Multiple Regression Analysis WithIncrease in Exercise Capacity from Before to 2 Weeks AfterAngioplasty as the Dependent Variable

Independent variables b* SE(b)† t Value p Value

Age 20.90 0.04 22.06 0.04Men 5.24 0.92 5.69 ,0.0001Smoking 23.58 0.84 24.27 ,0.0001Previous MI 22.75 0.79 23.48 ,0.001End-diastolic pressure 20.08 0.07 21.28 0.20Left ventricular ejection fraction 0.02 0.04 0.42 0.68LAD involvement‡ 1.47 0.75 1.97 0.05Vessels diseased§ 0.18 0.73 0.02 0.98

R squared 5 0.17; adjusted R squared 5 0.15.*Regression coefficients.†SE of regression coefficients.‡Dilation of the left descending artery alone or in combination with left

circumflex artery and/or right coronary artery.§One vessel or multivessel disease.

1032 THE AMERICAN JOURNAL OF CARDIOLOGYT VOL. 82 NOVEMBER 1, 1998

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