Noninvasive assessment of ventricular arrhythmias in clinical practice: prognostic implications

Frequency and complexity of ventricular arrhythmias increases with age and increasing severity of heart disease. However, fatal ventricular fibrillation occurs frequently in the absence of symptomatic warning arrhythmias. Several classifications of ventricular arrhythmias are discussed. The morphology of ventricular premature complexes (VPC), their frequency and complexity at rest, during ordinary activity, or after exercise do not influence life expectancy of subjects without heart disease, nor in those with coronary artery disease with no history of myocardial infarction. In the survivors of myocardial infarction, the frequency and "complexity" of ventricular arrhythmias appears to be an independent risk factor for sudden and nonsudden cardiac death. However, the low specificity and predictive value of ventricular arrhythmias makes their assessment difficult for practical purposes. The prognosis of most patients with ventricular arrhythmias is determined predominantly by the condition of the heart. "Complex" arrhythmias at rest and during exercise do not appear to worsen prognosis and life expectancy in individuals without heart disease. Ambulatory electrocardiographic monitoring has serious limitations as a guide for clinical decision making. Ventricular tachycardias in patients with coronary artery disease are not strictly related to the frequency and "complexity" of ventricular premature complex, but correlate with the presence of ventricular aneurysms, poor ventricular function and late potentials in the signal-averaged high frequency electrocardiogram. Recording of such late potentials is a new and promising noninvasive technique for identification of patients with serious arrhythmias but the sensitivity and specificity of this method remains to be established.