Noninvasive testing for ventricular arrhythmias.

Before treating patients with ventricular arrhythmias, it is important to classify the arrhythmias as benign, potentially lethal, or lethal. The vast majority of patients seen in clinical practice have benign or potentially lethal forms, which can be evaluated with noninvasive electrocardiographic techniques, such as continuous Holter monitoring and exercise testing. Lethal ventricular arrhythmias are probably best managed with invasive electrophysiologic testing. Quantitative Holter monitoring is essential both before starting antiarrhythmic therapy to establish a baseline and after starting therapy to determine whether treatment is effective, ineffective, or causing proarrhythmia. Whether adequate suppression of ventricular arrhythmias prevents sudden cardiac death is still unknown but is currently being evaluated by the Cardiac Arrhythmia Suppression Trial of the National Institutes of Health, Bethesda. The results are expected in the mid-1990s.