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Effect of angiotensin-converting enzyme therapy on QT interval dispersion
V Ranade1, J Molnar, T Khokher
1The American Institute of Therapeutics and Rush University, Lake Bluff, IL 60044, USA.
Insights
Angiotensin-converting enzyme (ACE) inhibitors significantly reduced QT dispersion (QTd), a marker of electrical instability, in chronic heart failure patients. This reduction may explain the decreased risk of sudden death associated with ACE therapy.
Area of Science:
- Cardiology
- Pharmacology
Background:
- Patients with chronic heart failure (CHF) face an elevated risk of sudden death, often linked to increased QT dispersion (QTd), indicating ventricular repolarization heterogeneity.
- Angiotensin-converting enzyme (ACE) inhibitors are known to reduce heart size and improve outcomes in CHF.
Purpose of the Study:
- To investigate whether ACE inhibitor therapy leads to a reduction in QTd, a key indicator of electrical instability in CHF patients.
Main Methods:
- Ninety-seven patients with CHF were evaluated.
- QTd and QTc dispersions were measured before and after 2 months of ACE inhibitor therapy.
- Heart rate, ejection fraction, and ACE levels were also assessed.
Main Results:
- ACE therapy resulted in a significant 25% reduction in normalized QTd (from 16 ± 4 to 12 ± 3).
- QTd decreased from 61 ± 14 to 47 ± 12 (P < .001), and QTc dispersions decreased from 71 ± 18 to 52 ± 14 (P < .001).
- Heart rate slowed significantly, and a strong negative correlation was observed between ejection fraction and QTd (r = -0.8; P < .001).
Conclusions:
- ACE inhibitor therapy rapidly improves ventricular repolarization, evidenced by a significant reduction in QTd.
- The observed decrease in QTd may contribute to the reduced risk of sudden cardiac death in CHF patients treated with ACE inhibitors.
Abstract:
Patients with chronic heart failure (CHF) have an increased risk for sudden death. This increased risk has been associated with increased QT dispersion (QTd), a reflection of the heterogeneity in ventricular repolarization. Angiotensin-converting enzyme (ACE) inhibitors have been reported to decrease heart size as well as decreasing morbidity and mortality in moderate-to-severe CHF. The aim of this study was to determine if ACE therapy is associated with a decrease in QTd, a marker for increased electrical instability. Ninety-seven patients were evaluated. The normalized QTd after 2 months of ACE therapy decreased from 16 +/- 4 to 12 +/- 3, a 25% reduction in dispersions. QTd also decreased from 61 +/- 14 to 47 +/- 12 (P < .001) and QTc dispersions decreased from 71 +/- 18 to 52 +/- 14 (P < .001). After 2 months of ACE inhibitor therapy, heart rate slowed significantly (RR intervals 765 +/- 198 before and 838 +/- 186 after ACE). There was a negative correlation between ejection fraction and QTd (r = -0.8; P < .001). The study also found no correlation between ACE level, percent converting enzyme inhibition, and QTd. The effects of ACE therapy appear early on in terms of repolarization changes. The reduction in QTd may explain the reduced sudden death mortality in patients with heart failure who are treated with ACE inhibitor therapy.