Ventricular tachycardia (VT) is diagnosed on the basis of at least three consecutive premature ventricular complexes on an electrocardiogram. Sustained VT lasts more than 30 seconds, and nonsustained VT lasts less than 30 seconds. The prevalence of nonsustained VT in elderly patients is reported to be between 2 and 16 percent, depending on the presence of pre-existing cardiac disease. VT is more common in patients who have left ventricular hypertrophy, an abnormal left ventricular ejection fraction or silent myocardial ischemia. Nonsustained VT is not associated with a higher risk of subsequent coronary events. Aronow recommends against treatment with antiarrhythmic medications in older asymptomatic patients with nonsustained VT but without cardiac disease. Patients with sustained VT, however, are at much greater risk of subsequent coronary events and sudden cardiac death.
The first principle of treatment is to determine the underlying cause of the VT, when possible, and treat that cause. Specifically, congestive heart failure, hypertension, left ventricular dysfunction or hypertrophy, hypoxia, digitalis toxicity and low serum levels of potassium and magnesium should be sought and treated. Myocardial ischemia should also be treated with beta blockers or coronary revascularization procedures when possible. Smoking and alcohol consumption should be avoided. Aspirin and beta blockers should be given to all elderly patients with a history of coronary artery disease unless there are specific contraindications to their use. Also, angiotensin-converting enzyme (ACE) inhibitors should be used in patients with low ejection fractions (40 percent or less), congestive heart failure or anterior myocardial infarction when not contraindicated. Finally, general measures should also include cholesterol lowering with statins in patients who have elevated low-density lipoprotein cholesterol levels.
No well-designed studies have shown that class I antiarrhythmic drugs can contribute to reduced rates of cardiac death or total mortality. In fact, many studies show a higher risk in patients treated with these medications, and the author recommends not using any of the class I antiarrhythmic agents (including quinidine, procainamide, encainide, flecainide, mexilitine and tocainide) in older patients with VT or complex ventricular arrhythmias. Calcium channel blockers have also shown no benefit in elderly patients with VT, and because of the risk of hemodynamic collapse when taken by patients with common forms of VT, they should not be used for this purpose.
Beta blockers, in contrast, have been shown to significantly reduce mortality after myocardial infarction, because of a decrease in recurrent myocardial infarction and sudden cardiac death. One study showed a 52 percent reduction in sudden cardiac death in patients who were treated for one year with propranolol. ACE inhibitors have inconsistently been associated with a decrease in total mortality in older patients with congestive heart failure. If not contraindicated, these agents should be used to treat older patients with VT (or complex ventricular arrhythmias) and congestive heart failure, anterior myocardial infarction or myocardial infarction with systolic dysfunction. Beta blockers should also be used in this group of patients. Although class III antiarrhythmic agents can suppress ventricular arrhythmias, they are also associated with torsade de pointes.
One medication, d-Sotalol, is associated with higher mortality than that occurring in patients receiving placebo. In general, beta blockers should be used instead of d-Sotalol in the treatment of VT or complex ventricular arrhythmias in patients who have cardiac disease. Similarly, amiodarone suppresses these arrhythmias but has a high incidence of toxicity, and it may be advisable to avoid this medication in favor of beta blockers.
Finally, a patient with life-threatening recurrent VT or ventricular fibrillation unresponsive to antiarrhythmic medications should receive invasive treatment. A variety of interventions are available, but the most effective is the automatic implantable cardioverter-defibrillator (AICD). The American College of Cardiology/American Heart Association guidelines for use of an AICD are shown in the accompanying table