The natural history of benign and potentially malignant ventricular arrhythmias with special reference to nonsustained ventricular tachycardia

Nonsustained ventricular tachycardia: identification and management of high-risk patients

NSVT is common in normal persons and in patients with a variety of heart diseases. When present in patients with coronary artery disease, particularly after a recent myocardial infarction, it is associated with an increased risk of sudden and nonsudden cardiac death. However, its prognostic significance in patients with nonischemic heart disease, with the possible exception of hypertrophic cardiomyopathy, remains controversial. In patients with coronary artery disease, certain diagnostic tools (e.g., determination of left ventricular function. PVS) help to identify low- and high-risk patients who may or may not benefit from antiarrhythmic treatment. There is no consensus at this point as to the best approach for identifying and treating high-risk patients. Ongoing clinical trials should provide important information on the roles of signal-averaged ECGs and PVS in the management of patients with NSVT and coronary artery disease. In the meantime, treatment should be individualized for each patient. beta-Blockers should probably be the first line of therapy to control symptoms. Asymptomatic potentially high-risk patients (i.e., those with LVEF < 40%) should be referred for enrollment in randomized controlled studies.

Avoiding interpretive pitfalls when assessing arrhythmia suppression after myocardial infarction: insights from the long-term observations of the placebo-treated patients in the Cardiac Arrhythmia Pilot Study (CAPS)

The Cardiac Arrhythmia Pilot Study (CAPS) was a 1 year trial that analyzed the safety and effectiveness of arrhythmia suppression in 502 patients surviving acute myocardial infarction who had greater than or equal to 10 ventricular premature depolarizations/h or greater than or equal to 5 runs of ventricular tachycardia on a Holter recording obtained 6 to 60 days after the acute infarction. Because 100 of these patients received placebo in a double-blind fashion for 1 year, a comprehensive objective analysis was performed of spontaneous arrhythmia changes based on real data rather than statistical estimates. In the CAPS placebo group, 19% developed some serious clinical event in 1 year (death, heart failure, proarrhythmia) that could likely be attributable to antiarrhythmic drug toxicity. A significant reduction in the frequency of ventricular premature depolarizations (p = 0.004) occurred in the first few weeks of "therapy" with a further significant (p less than 0.04) decrease between 3 to 12 months. After initiation of placebo antiarrhythmic therapy, 27% had "apparent ventricular premature depolarization suppression" (greater than or equal to 70% reduction) after one Holter recording evaluation and nearly half (48%) after six Holter recordings to assess suppression were performed.(ABSTRACT TRUNCATED AT 250 WORDS)

Clinical development of moricizine as an antiarrhythmic agent

The primary development of moricizine as an antiarrhythmic agent has occurred in the Soviet Union and the United States. The data in this presentation are based on the 1,844 subjects/patients (1,817 adults and 27 pediatric patients) who participated in 34 controlled studies and 3 uncontrolled compassionate-use programs conducted in the United States. Of the 1,817 adults, 443 received only placebo or comparative agents and 1,374 received moricizine in daily doses of 50 to 1,800 mg. A total of 1,190 adult patients (mean age 59 years) had ventricular arrhythmias classified as either benign (8%), potentially lethal (58%) or lethal (33%). Most patients had a history of greater than or equal to 1 cardiovascular disease, including coronary artery disease, previous myocardial infarction and congestive heart failure. Antiarrhythmic activity was assessed by four methods: 24-hour ambulatory electrocardiographic monitoring, programmed electrical stimulation, exercise tolerance tests, and global evaluation (only for some patients in the compassionate-use program). In addition, the effects of moricizine on symptoms associated with ventricular arrhythmias were assessed. The safety variables evaluated included adverse experiences, proarrhythmia, congestive heart failure, other cardiovascular effects, death, chest x-ray, ophthalmic examinations, neuroleptic phenothiazine effects and clinical laboratory tests.

Risk-benefit profiles of antiarrhythmic therapy

Whereas much has been learned of the mechanisms and pathophysiology of cardiac arrhythmias, treatment remains controversial and is largely empiric. Cardiac arrhythmias range in severity from innocuous to fatal; antiarrhythmic agents offer differing degrees of efficacy, inefficacy or toxicity. For an arrhythmia that needs treatment, there is no reliable or easy method for selecting the most appropriate antiarrhythmic drug. Antiarrhythmic treatment is justified for arrhythmias that are symptomatic or hemodynamically significant, the risk of lethality dictating the degree of drug toxicity that might be tolerated. The treatment of prognostically important arrhythmias is indicated if their suppression is rewarded by an improved prognosis. However, these arrhythmias are often merely indicators of a bad prognosis rather than the cause of death. Assessment of the risk-benefit ratio of antiarrhythmic treatment principally depends on the perceived risk and symptomatology of the arrhythmia and the efficacy and toxicity of the antiarrhythmic drug. Beta-adrenoceptor blocking drugs offer optimal risk-benefits for the prevention of ventricular fibrillation (infarct survivors and long QT syndrome); disopyramide and the class IC agents offer acceptable risk-benefit ratios for the treatment of ventricular tachycardia, whereas no antiarrhythmic drug offers an acceptable risk-benefit for the suppression of asymptomatic "cosmetic" atrial or ventricular ectopic beats.