Rhythm control therapy in a female patient

A 72-year-old woman with symp­toms of palpitations and fatigue for the past several months was seen in the outpatient department. The 12-lead electrocardiogram (ECG) showed atrial fibrillation with a ventricular rate of 120 beats per minute (bpm). No further abnormalities were noted on the ECG. The patient had a history of hypertension and a previous episode of persistent atrial fibrillation more than 1 year earlier. She was successfully cardioverted. She was taking 100 mg of metoprolol (Lopressor, Toprol XL) daily, 50 mg of losartan (Cozaar) daily, and acenocoumarol.

Physical examination showed no abnormalities, except for high blood pressure, at 160/100 mm Hg. Echo­car­diography and exercise testing showed left ventricular hypertrophy and moderate left ventricular function, but no ischemia. Because the patient was symptomatic, an electrical cardioversion was performed. Sinus rhythm was successfully restored, but the heart rate in sinus rhythm was only 30 bpm. The patient was symptomatic, with fatigue and dizziness during activities. Meto­prolol was discontinued, and the pa­tient was monitored in the hospital. After 30 hours, atrial fibrillation reoccurred (heart rate, 110 bpm). It was decided to accept atrial fibrillation. She was prescribed 240 mg of verapamil (Calan, Covera-HS, Isoptin SR, Verelan PM) daily for rate control. Her symptoms decreased, and her blood pressure was 140/90 mm Hg.

This case illustrates the potential pitfalls of pharmacologic rhythm control therapy in female patients, as we observed in the Rate Control Versus Electrical Cardioversion (RACE) study. By electrical cardioversion, a sick sinus syndrome was unmasked. For­tun­ately, atrial fibrillation relapsed and was subsequently accepted. As there were no atrioventricular conduction disorders, a negative chronotropic drug was instituted for rate control.