Effect on exercise performance of enalapril therapy initiated early after myocardial infarction. Nordic Enalapril exercise Trial

Captopril reduces the VE/VCO2 ratio in myocardial infarction patients with low ejection fraction

STUDY OBJECTIVES

To determine whether captopril (CAP) therapy had an effect on the minute ventilation/carbon dioxide output (VE/VCO2) ratio at submaximal levels of exercise in asymptomatic patients with reduced left ventricular function after myocardial infarction.

DESIGN

Double blinded, randomized, prospective, repeated measures.

PATIENTS AND INTERVENTIONS

One hundred thirty-five patients with left ventricular ejection fractions of < 40% were randomly assigned to a treatment group (CAP; n = 62) or a placebo group (PLC; n = 73). Subjects had cycle ergometer exercise tests at 2 to 6 months (T1), 10 to 14 months (T2), and > 22 months (T3) postmyocardial infarction.

MEASUREMENTS

Oxygen uptake (VO2), VCO2, and VE were measured throughout each exercise test. Dependent variables were peak VO2 (VO2peak), the ventilatory anaerobic threshold (VAT), and the VE/VCO2 ratio measured at 30 W and at 75% VO2peak.

RESULTS

VO2peak and VAT did not differ as a result of treatment (CAP vs PLC; p = 0.92 and 0.80) or over time (T1 vs T2 vs T3; p = 0.51 and 0.07). VE/VCO2 was significantly lower for CAP at 30 W (p = 0.05) and, although lower at 75% VO2peak, did not obtain statistical significance (p = 0.22). The between group differences were larger at T2 and T3 when compared with T1.

CONCLUSIONS

CAP resulted in a reduced VE/VCO2 ratio during submaximal exercise. The reduced ventilation may permit patients to perform their normal activities of daily living at a lower perception of difficulty, reduce symptoms, and provide an improved quality of life.

Effects of enalapril on left ventricular function and exercise performance after a first acute myocardial infarction. The EDEN Study Investigators

AIMS

To study the effects of early use of enalapril on left ventricular function and exercise capacity after a first acute myocardial infarction, 356 patients without overt signs of congestive heart failure were randomly allocated to receive placebo or enalapril between days 7 and 14 after a first myocardial infarction. The study was conducted double-blind in 40 hospitals throughout Spain.

METHODS AND RESULTS

At baseline and after 26 weeks of follow-up exercise stress tests, Doppler-echocardiograms and isotopic ventriculography were performed in study participants. At the end of follow-up, patients in the enalapril group had lower end-systolic volume compared to those in the placebo group (55 vs. 62 ml; P=0.05). No difference in exercise capacity was evident between both groups.

CONCLUSION

The present study shows that enalapril therapy administered between 7 and 14 days after a first acute myocardial infarction decreases end-systolic volume and may inhibit the remodeling process of the left ventricle.

Physical working capacity after acute myocardial infarction in patients with low ejection fraction and effect of captopril

Previous studies after acute myocardial infarction (AMI) have reported conflicting results on the effects of angiotensin-converting enzyme inhibition on physical working capacity. In an effort to provide more insight into this subject, we examined the effects of captopril on working capacity of patients who had low ejection fractions but no congestive heart failure after AMI. One hundred sixty-six participants were recruited from 5 centers after randomization to either captopril or placebo for the Survival and Ventricular Enlargement study. Upright cycle ergometer tests were performed with continuous measurements of respiratory gases at 4, 12, and 24 months after AMI. Our study concurs with 2 of 3 previous post-AMI studies and supports the conclusion that working capacity is not affected by angiotensin-converting enzyme inhibition at 4 or 12 months after AMI in patients without congestive heart failure. In addition, no significant effect of captopril was noted at 24 months after AMI. Peak oxygen uptake tended to decrease between 12 and 24 months in the placebo group by an average (+/- SD) of -22 +/- 322 ml/min (n = 66), but to increase in the captopril group (+62 +/- 289, n = 57), a difference that was significant (Mann-Whitney chi-square, p = 0.02). This post-hoc observation suggests that a late beneficial effect may have been masked by inadequate study duration. Known benefits of captopril appear not to include an increase in working capacity within the first 24 months after AMI.