The Effect of Angiotensin Converting Enzyme Inhibitor Therapy on Electrocardiographic Parameters and QT Dispersion in Left Heart Failure

Abstract

Background: Changes in electrocardiographic (ECG) parameters, such as QT intervals and RR intervals, have been hypothesized to correlate with an elevated mortality risk among heart failure patients. The objective of our study was to examine the immediate effects of angiotensin-converting enzyme (ACE) inhibitor utilization on QT dispersion (QTd) and other ECG parameters in individuals diagnosed with left heart failure.

Methods: A total of forty-one patients diagnosed with heart failure and prescribed enalapril 10 mg at the cardiology outpatient clinic during the period of August to October 1999 were included in this evaluation. Out of these, twenty-six patients who met the criteria for ECG measurements were enrolled in the study. At the beginning of the study, 12-lead ECG and echocardiography measurements were obtained, while 12-lead ECG measurements were taken again at the 6th week of treatment. Additional ECG parameters, such as QTd, QT max, QTc max, and RRCV, were derived from the ECG data of the patients. The values at baseline and week 6 were then compared.

Results: Twenty-six patients exhibited baseline values for QT max, QTc max, RRCV, and QTd of 381.9±30.47 msec, 476.3±31.2 msec1/2, 4.72±3.15, and 56.9±16.7 msec, respectively. These values were evaluated after six weeks of enalapril treatment, yielding measurements of 383.5±36.33 msec, 470.2±30.7 msec1/2, 4.96±2.94, and 51.5±27.8 msec, respectively. No significant differences were observed in these four parameters before and after treatment. However, among the subgroup of patients with a baseline QTd ≥ 50 msec (n=21), the initial QTd value measured 63.3±11.1 msec, whereas the QTd value after six weeks was 50.5±24.4 msec (p=0.032).

Conclusion: In individuals diagnosed with heart failure, the utilization of enalapril did not result in a substantial alteration in electrocardiogram (ECG) parameters, particularly the corrected QT interval dispersion (QTd), over a brief duration of time. However, among patients exhibiting a baseline QTd interval exceeding 50 milliseconds, a significant reduction in QTd was observed following a 6-week administration of enalapril.