Supraventricular tachycardia in patients with cystic fibrosis.

Reports on arrhythmias in cystic fibrosis (CF) patients are limited. Four CF patients treated at our center had recurrent supraventricular tachycardia (SVT). Three had cor pulmonale, as evidenced by echocardiogram, and all had baseline tachycardia. Twenty-four hour Holter monitoring in three patients showed ectopic atrial pacing and premature atrial and ventricular contractions in one patient, rare PVCs in another, and SVT in all three. All patients had significant bronchospasm requiring the use of theophylline, prednisone, and frequent daily doses of beta-2 adrenergic agonists; two also used nebulized atropine. Average theophylline level for the group was 13.4 micrograms/ml during SVT. There was no correlation between pulmonary obstruction and the frequency of SVT. Factors such as cor pulmonale, ectopy, hypoxia, infection, intensive combination bronchodilator therapy, and corticosteroids probably interacted to precipitate SVT. Altered autonomic responses and a myocardial infiltrative process noted in some patients with CF may also play a role in causing arrhythmias.