Related Experiment Videos
Methodology for clinical trials with antiarrhythmic drugs to prevent cardiac death: US experience
Insights
Sudden cardiac death is a major health issue. The Cardiac Arrhythmia Pilot Study (CAPS) evaluated antiarrhythmic drugs in high-risk patients, aiming to suppress ventricular arrhythmias and assess treatment feasibility.
Area of Science:
- Cardiology
- Clinical Trials
- Pharmacology
Background:
- Sudden cardiac death (SCD) poses a significant public health challenge, with identified high-risk groups including cardiac arrest survivors and patients with heart failure.
- Ventricular arrhythmias following myocardial infarction (MI) increase mortality risk, but effective treatments remain unproven.
- Current methods for assessing antiarrhythmic drug efficacy in high-risk patients are difficult to interpret.
Purpose of the Study:
- To identify a therapeutic strategy for suppressing ventricular arrhythmias with acceptable adverse effects.
- To establish efficient methods for patient recruitment and evaluation of antiarrhythmic drug efficacy.
- To assess the feasibility of a 1-year treatment protocol and the utility of behavioral studies.
Main Methods:
- The Cardiac Arrhythmia Pilot Study (CAPS) enrolled 502 patients at high risk for ventricular arrhythmias.
- Patients were randomized into five groups: placebo and four antiarrhythmic drug arms (Class IC and Class IA).
- Dose adjustments and crossover to alternative drug classes were permitted based on efficacy criteria.
Main Results:
- The study aimed to suppress ventricular arrhythmias and evaluate treatment feasibility.
- Methods for case finding and efficacy evaluation were assessed.
- Patient recruitment and 1-year treatment maintenance feasibility were demonstrated.
Conclusions:
- The CAPS study provided valuable data on therapeutic strategies for ventricular arrhythmias.
- It demonstrated the feasibility of conducting controlled trials in patients with malignant arrhythmias.
- The findings support further research into effective antiarrhythmic treatments for high-risk cardiovascular patients.
Abstract:
Sudden cardiac death is a massive public health problem that claims almost a half million lives a year in the United States. Several high-risk groups have been identified: survivors of cardiac arrest; patients with recurrent sustained ventricular tachycardia; survivors of myocardial infarction (MI) who have more than 10 ventricular premature depolarizations (VPD) per hour or repetitive VPD; and patients with class III or IV congestive heart failure (CHF) and unsustained ventricular tachycardia. The effects of open label drug treatment have been tested in survivors of cardiac arrest or sustained ventricular tachycardia using either electrophysiologic studies or 24-hour ECG recordings and exercise testing. Patients classified as drug responders using these methods have a lower mortality rate during follow-up than do those classified as nonresponders. This result is difficult to interpret. The test procedures may be identifying effective drugs, or alternatively, drug testing may identify high- and low-risk groups even though the drugs have no effect on survival. Recently, study designs have been proposed for conducting controlled trials in patients with malignant arrhythmias. Ventricular arrhythmias after MI have been the subject of intensive study for the past 20 years. About 20% of these patients have ventricular arrhythmias between 6 and 90 days after MI. The presence of ventricular arrhythmias after MI increases the risk of dying two- to fourfold. Arrhythmias predict death independently of left ventricular dysfunction. However, it has not been demonstrated that treatment of ventricular arrhythmias after MI significantly decreases mortality. The goals of the Cardiac Arrhythmia Pilot Study (CAPS) were: to find a therapeutic strategy that could significantly suppress ventricular arrhythmias with an acceptable adverse effect rate; to determine efficient methods for case finding; to identify efficient methods for evaluating the efficacy of antiarrhythmic drug therapy; to demonstrate the feasibility of recruiting patients and maintaining treatment over a 1-year period; and to evaluate the feasibility and usefulness of behavioral studies. The study enrolled 502 patients, randomizing approximately 100 patients each into one of five treatment limbs: one group treated with placebo, and four treated with antiarrhythmic drugs (two with class IC and two with class IA action). Dose adjustment was permitted; patients who failed to satisfy the criteria for drug efficacy were permitted to cross over to a second drug (patients on class IC agents crossed over to class IA agents and vice versa).(ABSTRACT TRUNCATED AT 400 WORDS)