Effect of exercise on cycle length in atrial flutter.

OBJECTIVE To examine the effect of exercise on cycle length in atrial flutter. PATIENTS 15 patients with chronic atrial flutter. Seven patients were taking digoxin and six verapamil; two were not taking medication. METHODS All patients underwent bicycle ergometry. Flutter cycle length was measured at rest and at peak exercise. RESULTS Mean flutter cycle length increased from 245 ms to 256 ms (P = 0.002). Six patients developed 1:1 atrioventricular conduction. Significant increases in flutter cycle length were observed irrespective of development of 1:1 atrioventricular conduction and use of digoxin and verapamil. CONCLUSION Exercise prolongs flutter cycle length. This effect would promote development of 1:1 atrioventricular conduction during exercise, causing inordinately high ventricular rates.