Chapter 32
Cardiac Arrhythmias
300,000 sudden cardiac deaths per year in the US
Cardiac Arrhythmias: When the Heart Loses Its Rhythm
Sudden death from cardiac causes in the US occurs in the range of 300,000 to 350,000 cases annually, with the majority caused by acute ventricular tachyarrhythmias.
A cardiac arrhythmia is any deviation from the normal heartbeat pattern — abnormalities of impulse formation or conduction that disrupt the normal sequence of atrial and ventricular activation. The critical lesson from the CAST trial is that antiarrhythmics can kill: certain drugs increased mortality vs placebo. Today we live in the era of outcome-based antiarrhythmic decision making, where the goal is maximum therapeutic benefit with minimal proarrhythmic risk.
CAST Trial — The Watershed Moment
The Cardiac Arrhythmia Suppression Trial (CAST) proved that suppressing PVCs with encainide and flecainide INCREASED mortality vs placebo. This shattered the idea that 'suppress the arrhythmia = better outcome.' Now antiarrhythmics are reserved for symptomatic or life-threatening arrhythmias only.