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The effects of tiapamil were studied in 10 patients with antegrade preexcitation using programmed stimulation of the heart. Before administration of the drug, it was possible to initiate sustained orthodromic tachycardia in 7 patients, antidromic tachycardia in 2 and atrial echoes in 1 case by premature atrial and/or ventricular stimulation. An intravenous bolus of 2 mg/kg tiapamil terminated the tachycardia in 7 out of 8 cases by blocking the A-V node. The tachycardia continued at a reduced heart rate in 1 case with a nodoventricular bypass. Tiapamil lengthened the effective A-V nodal refractory period in 1 patient in whom it could be measured and the atrial effective refractory period in 1 case but did not prolong the antegrade or retrograde refractory periods of the accessory pathway. Only in 1 case was the antegrade effective refractory period of the accessory pathway shortened by tiapamil. The A-V nodal conduction time (A-H interval) was prolonged. Following tiapamil it was not possible to initiate the tachycardia in 4 cases and atrial echoes in 1 case; in 2 patients the tachycardia zone widened and in 3 it was not altered. In the latter, the cycle length of the tachycardia increased. Tiapamil appears to be of therapeutic value for the termination of tachycardia and also for its prevention in some cases. In others, it may facilitate the initiation of tachycardia. The delayed A-V nodal conduction during sinus rhythm augments the area of ventricular preexcitation which may facilitate the electrocardiographic localization of the accessory pathway.

The incidence of supraventricular arrhythmias is high following open-heart surgery, occurring in 25% to about 50% of patients. The most common of these arrhythmias is atrial fibrillation (AF). Postoperative AF has been associated with increased incidence of other complications and increased hospital length of stay. Atrial arrhythmias are most frequent in the first two to three days after cardiothoracic surgery, but they can occur at any point in the recovery period. Age and concomitant valular heart disease are consistently the independent factors most strongly associated with postoperative atrial fibrillation. Prevention of AF seems to be a reasonable clinical goal, and, consequently, many randomized trials have evaluated the effectiveness of pharmacological and nonpharmacological interventions for prevention of AF. The main indication for AF prophylaxis remains the shorteningof length of hospital stay and possibly reduction in stroke. The optimal treatment strategies for reducing postoperative AF are not well established. Commonly used therapeutic approaches include the use of rate-controlling drugs such as beta-blockers, calcium antagonists, and digoxin. Some pharmacological strategies including beta-blockers, sotalol, and amiodarone have shown to reduce risk of postoperative AF and may reduce length of hospital stay. There is no convincing evidence that reducing postoperative AF reduces stroke. This review summarizes current evidence from randomized controlled trials to estimate the effect of pharmacological and non pharmacologic interventions on the occurrence of AF after open-heart surgery and its effects on postoperative outcome.

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