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ESSENTIALS OF DIAGNOSIS
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ESSENTIALS OF DIAGNOSIS
Common but rarely symptomatic.
Ambulatory ECG monitoring to quantify daily burden of PVCs. Asymptomatic patients with > 10% PVC burden should have periodic echocardiogram to exclude development of LV dysfunction.
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GENERAL CONSIDERATIONS
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Ventricular premature beats, or PVCs, are isolated beats typically originating from the outflow tract or His-Purkinje regions of ventricular tissue. In most patients, the presence of PVCs is a benign finding; however, they rarely may trigger ventricular tachycardia or ventricular fibrillation, especially in patients with underlying heart disease.
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Patients may be asymptomatic or experience palpitations, dizziness, or vague chest pain. Some patients feel the irregular beat; however, symptoms can often be secondary to post-PVC augmentation of contractility or a post-PVC compensatory pause. Exercise generally abolishes premature beats in normal hearts, and the rhythm becomes regular. PVCs are characterized by wide QRS complexes that differ in morphology from the patient’s normal beats. They are usually not preceded by a P wave, although retrograde ventriculoatrial conduction may occur. Unless the latter is present, there is a fully compensatory pause (ie, without change in the PP interval). Bigeminy and trigeminy are arrhythmias in which every second or third beat is premature (eFigure 10–67). Ambulatory ECG monitoring may reveal more frequent and complex PVCs than occur in a single routine ECG. An increased frequency of PVCs during exercise is associated with a higher risk of cardiovascular mortality and should be investigated further.
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If no associated cardiac disease is present and if the ectopic beats are asymptomatic, no therapy is indicated. Mild symptoms or anxiety from palpitations may be allayed with reassurance to the patient of the benign nature of this arrhythmia. If PVCs are frequent (bigeminal or trigeminal pattern) or multifocal, electrolyte abnormalities (ie, hypo- or hyperkalemia and hypomagnesemia) and occult cardiac disease (ie, ischemic heart disease or LV dysfunction) should be excluded. In addition, an echocardiogram should be performed in patients in whom a burden of PVCs of greater than 10,000 per day has been documented by ambulatory ECG monitoring. Pharmacologic treatment is indicated only for patients who are symptomatic or who develop cardiomyopathy thought to be due to a high burden of PVCs (generally greater than 10% of daily heart beats). Beta-blockers or nondihydropyridine calcium channel blockers are appropriate as first-line therapy. The class I and III antiarrhythmic agents (see Table 10–9) may be effective in reducing PVCs but are often poorly tolerated and can be proarrhythmic in ...