EFFECTS OF ANGIOTENSIN-CONVERTING ENZYME-INHIBITOR THERAPY ON PRESENCE OF LATE POTENTIALS DETECTED USING SIGNAL-AVERAGED ELECTROCARDIOGRAPHY IN PATIENTS WITH CONGESTIVE-HEART-FAILURE

Background: Angiotensin-converting enzyme (ACE) inhibitors have been s hown to improve the mortality rate in patients with congestive heart f ailure. The exact mechanism of this effect is uncertain. Signal-averag ed electrocardiography has been used to evaluate the presence of late potentials as a marker for sudden cardiac death. We examined prospecti vely the effects of ACE inhibitor therapy on signal-averaged ECGs and ventricular arrhythmia frequency in 20 patients with moderate to sever e left ventricular dysfunction and symptomatic congestive heart failur e. Methods: A signal-averaged ECG and 24 h Holter monitor were perform ed immediately before and both 1 week and 6 weeks after captopril init iation. The mean dose of captopril at 6 weeks was 38+/-31 mg. The pati ents (19 men and one woman, mean age 63+/-12 years) had a baseline eje ction fraction of 22+/-7% and mean functional class of 2.6+/-0.5. The cause of congestive heart failure was coronary artery disease in 18 pa tients, idiopathic cardiomyopathy in one, and valvular disease in one. Results: All three signal-averaged ECG time-domain parameters tended to improve over the course of the study (study 1, 2, 3: QRS duration ( ms) = 108+/-11, 106+/-12, 105+/-11; low-amplitude signal duration (ms) = 30+/-8, 31+/-10, 28+/-10; root mean voltage (muV)=33+/-20, 37+/-24, 40+/-2, respectively). These changes were not statistically significa nt, although the improvement in QRS duration was nearly so with P=0.06 . The occurrence and complexity of ventricular ectopy did not appear t o be consistently altered. Conclusion: ACE inhibitor therapy with capt opril did not appear to alter ventricular ectopy over the course of th is study. However, the trends toward improvement of signal-averaged EC G parameters deserve further evaluation in a larger and longer-term st udy.