Structural heart disease: its importance in association with antiarrhythmic drug therapy.

The presence or absence of structural heart disease is an important factor to consider prior to initiating antiarrhythmic drug therapy with a class I or class III antiarrhythmic agent. An appropriate screen for structural heart disease and other associated proarrhythmic risk factors should include a complete history, physical examination, electrocardiogram (ECG), and echocardiogram in all patients; exercise test and Holter monitoring in many/most selected patients; and a signal-averaged ECG, chest x-ray, and invasive procedures only in selected/occasional patients. Whether and when to obtain the tests that are not indicated for all patients must be determined by each individual physician's practice strategy and philosophy, while keeping in mind the likelihood of finding an abnormality in a particular patient, the arrhythmia being treated, the nature of the drug to be used, and cost-effectiveness issues. Given the low incidence of proarrhythmia under most circumstances, screening for clinically unrecognized structural heart disease may appear difficult to justify in the current era of cost containment. However, due to the potential lethality of proarrhythmia, particularly in patients with structural heart disease, pre-drug assessment is prudent.