Identify those patients who would benefit either from an electrophysiologic (EP) study and/or EP therapy.

The following groups of patients have been shown to be at increased risk for sudden cardiac death:

• History of sudden cardiac death
• History of sustained monomorphic ventricular tachycardia or sudden cardiac death
• Reduced LVF (EF<0.40) and nonsustained ventricular tachycardia
• Reduced LVF (EF<0.40) and syncope of undetermined etiology
• Reduced LVF (EF <0.30) and prior history of MI

DISCUSSION

Patients with CAD and reduced LVF (i.e., EF <0.40) are at increased risk for life-threatening ventricular arrhythmias. Clinical markers for increased risk of ventricular arrhythmias include a prior history of sustained monomorphic ventricular tachycardia or sudden cardiac death without a precipitating cause, such as ischemia, infarction, medications, or electrolyte disorders. If there is no evidence for reversible cause of ventricular arrhythmias, patients should be referred to an electrophysiologist, as these patients may benefit from an intervention, such as an automatic implantable cardioverter-defibrillator (AICD) (AVID, 1997).

The MUSTT trial demonstrated that patients presenting with CAD, LVF<0.40 and nonsustained monomorphic ventricular tachycardia could be successfully risk-stratified between high- and low-risk groups, if ventricular tachycardia could be induced during EP study (Buxton et al., 2000). Both the MUSTT (Buxton et al., 1999) and MADIT (Moss et al., 1996) trials showed a mortality benefit in patients with inducible, sustained, ventricular tachycardia that received an AICD.

Patients with CAD, LV dysfunction (EF <0.40), and syncope of undetermined etiology may also benefit from an EP study. In an evaluation of 67 patients with CAD and syncope of undetermined etiology, Mittal et al. (1999) found that 48% of these patients had a plausible diagnosis at EP study, most of whom had inducible, sustained, monomorphic ventricular tachycardia.

Stable angina patients who have survived sudden cardiac death or sustained ventricular tachycardia are generally referred for coronary angiography to identify coronary lesions that, if treated appropriately, could relieve the ischemic substrate for lethal arrhythmias (Every, 1992).

EVIDENCE