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Prognostic value of prolonged ventricular repolarization following myocardial infarction: the BHAT experience. The
R W Peters1, R P Byington, A Barker
1Department of Medicine, VA Medical Center, Baltimore, Maryland 21218.
Insights
Prolonged QTc interval after heart attack indicates higher mortality risk. Propranolol offers similar benefits for patients regardless of QTc interval status, highlighting its effectiveness in post-myocardial infarction care.
Area of Science:
- Cardiology
- Clinical Trials
- Electrophysiology
Background:
- The Beta Blocker Heart Attack Trial (BHAT) investigated propranolol's efficacy post-myocardial infarction.
- Electrocardiogram (ECG) parameters are crucial for assessing cardiac risk.
Purpose of the Study:
- To determine the prognostic value of QTc interval prolongation in post-myocardial infarction patients.
- To assess the impact of propranolol treatment on mortality and reinfarction in relation to QTc interval.
Main Methods:
- Randomized, double-blind trial involving 3837 patients post-myocardial infarction.
- Patients received propranolol or placebo, with ECGs recorded at baseline, 12, and 24 months.
- Statistical analysis correlated QTc interval with mortality and reinfarction outcomes.
Main Results:
- A significant positive correlation was observed between baseline QTc interval prolongation and increased mortality and sudden death.
- This association was independent of the treatment group (propranolol vs. placebo).
- Similar trends were noted for non-sudden death and non-fatal reinfarction.
Conclusions:
- QTc interval prolongation identifies a high-risk subgroup among post-myocardial infarction patients.
- The mortality benefit of propranolol was consistent in patients with both normal and prolonged QTc intervals.
Abstract:
In the Beta Blocker Heart Attack Trial (BHAT), 3837 patients were randomized to propranolol (180-240 mg/day) or placebo 5-21 days after a documented myocardial infarction and were followed in a double blind manner for a mean period of 25 months. Twelve lead electrocardiograms were routinely obtained at the time of randomization (baseline electrocardiogram) and at 12 and 24 months of follow-up. There was a positive correlation between baseline QTc interval prolongation (but not QT prolongation) and mortality and sudden death that was independent of treatment group. The data for non-sudden death and non-fatal reinfarction exhibit similar trends. We conclude that: (1) QTc prolongation identifies a high risk subset of post myocardial infarction patients. (2) The relative benefit of propranolol is similar in patients with normal and prolonged QTc.