Drug-induced ventricular tachyarrhythmias can be caused by cardiovascular drugs, noncardiovascular drugs, and even nonprescription agents. They can result in arrhythmic emergencies and sudden cardiac death. If a new arrhythmia or aggravation of an existing arrhythmia develops during therapy with a drug at a concentration usually considered not to be toxic, the situation can be defined as proarrhythmia. Various cardiovascular and noncardiovascular drugs can increase the occurrence of polymorphic ventricular tachycardia of the 'torsade de pointes' type. Antiarrhythmic drugs, antimicrobial agents, and antipsychotic and antidepressant drugs are the most important groups. Age, female sex, and structural heart disease are important risk factors for the occurrence of torsade de pointes. Genetic predisposition and individual pharmacodynamic and pharmacokinetic sensitivity also have important roles in the generation of arrhythmias. An increase in spatial or temporal dispersion of repolarization and a triangular action-potential configuration have been identified as crucial predictors of proarrhythmia in experimental models. These studies emphasized that sole consideration of the QT interval is not sufficient to assess the proarrhythmic risk. In this Review, we focus on important triggers of proarrhythmia and the underlying electrophysiological mechanisms that can enhance or prevent the development of torsade de pointes.

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Background and Purpose-Supraventricular premature beats (SPBs) may help to assess the risk of atrial fibrillation (AF) in patients with cryptogenic stroke and therefore guide therapy. Methods-An internal loop recorder was implanted in consecutive patients with acute cryptogenic stroke. The occurrence and quantity of SPBs and short supraventricular runs (SVRs) in 24-hour ECG in patients with and without future AF were analyzed. We evaluated the relative risk of the upper quartile of SPB and SVR patients against the remainder and used binary logistic regression to evaluate a possible independent influence of SPBs and SVRs on AF occurrence.

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