Data monitoring in the cardiac arrhythmia suppression trial
L M Friedman1, J D Bristow, A Hallstrom
1National Heart, Lung, and Blood Institute, Bethesda, MD 20892.
Insights
The Cardiac Arrhythmia Suppression Trial (CAST) found antiarrhythmic drugs harmful, leading to early termination. This highlights critical data monitoring challenges in clinical trials with unexpected adverse findings.
Area of Science:
- Cardiology
- Clinical Trials
- Pharmacology
Background:
- The Cardiac Arrhythmia Suppression Trial (CAST) investigated antiarrhythmic drug efficacy post-myocardial infarction.
- Patients had ventricular arrhythmias and reduced ejection fraction, common after heart attacks.
Purpose of the Study:
- To review data-monitoring committee decisions in CAST, a trial stopped early for safety concerns.
- To discuss practical challenges of managing unexpected adverse findings during clinical trials.
Main Methods:
- Review of the data-monitoring committee's considerations and decisions during the CAST trial.
- CAST was a randomized, double-blind trial comparing three antiarrhythmic agents (encainide, flecainide, moricizine) against placebo.
Main Results:
- CAST demonstrated that the three antiarrhythmic agents were harmful.
- Encainide and flecainide were discontinued first, followed by moricizine, leading to early trial cessation.
Conclusions:
- The trial's complexity and mid-study modifications presented unique data-monitoring issues.
- Handling dramatic, unexpected results and adapting study goals require flexibility.
- Balancing trial data with prevailing medical practice poses significant challenges.
Objective:
This report discusses practical aspects of data monitoring in a clinical trial which stopped ahead of schedule due to adverse findings.
Design:
A review of the considerations and decisions made by the data-monitoring committee of the Cardiac Arrhythmia Suppression Trial (CAST), a randomized, double-blind clinical trial.
Patients:
CAST consisted of men and women with a recent myocardial infarction, asymptomatic or minimally symptomatic ventricular arrhythmias, and reduced left ventricular ejection fraction.
Interventions:
In CAST, 3 antiarrhythmic agents, encainide, flecainide, and moricizine, were compared against placebo.
Main Outcome Measures:
The main outcome measures in CAST were arrhythmic death and total mortality.
Results:
CAST found the 3 agents to be harmful. Encainide and flecainide were stopped first. Subsequently, moricizine was discontinued ahead of schedule.
Conclusions:
The complexity of the study design and a midcourse protocol modification raise several data-monitoring issues not previously discussed. These include how to handle apparently dramatic yet unexpected results, the need for flexibility in modifying study design and goals, and the conflict between existing study data and both conventional wisdom and medical practice.
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