Holter/Exercise and Electrophysiologic Methods for Evaluating Drug Therapy for Malignant Ventricular Arrhythmias: Do We Need Both Models?

Many studies have shown the malignant potential of symptomatic sustained ventricular arrhythmias, i.e., ventricular tachycardia (VT) or ventricular fibrillation (VF). Routine clinical evaluation usually reveals ample evidence for the existence of heart disease in patients with these arrhythmias. Coronary heart disease is by far the most frequently occurring etiologic form of heart disease (about 80%) followed by cardiomyopathy and valvular heart disease. Often ventricular scarring and/or hypertrophy is present in patients with sustained VA. Left ventricular dysfunction is apparent clinically as heart failure or detectable by radionuclide ventriculography. A 24-hour ECG recording frequently will reveal repetitive ventricular arrhythmias, including runs of unsustained VT. When antiarrhythmic drug treatment is stopped, electrophysiologic studies are capable of inducing sustained VT or VF in about 80% of those who present with recurrent sustained VT as the clinical arrhythmia and in about 70% of those who had a cardiac arrest and were found in VF (1–4).