Atrial fibrillation: prevalence and management in an acute general medical unit

Atrial fibrillation (AF) is a common comorbid condition in patients admitted to hospital. In managing patients with AF, recent research has highlighted the importance of heart rate control, cardioversion, maintenance of sinus rhythm and anticoagulation for the prevention of thromboembolism.

To determine the prevalence of AF in patients admitted acutely to the general medical service at Auckland Hospital and to assess the adequacy of heart rate control, the number cardioverted and the use of warfarin to prevent thromboembolism.

Prospective review of all acute admissions to the general medical service over a 12 week period. Information was collected from hospital notes on the patients' present and past medical conditions, admission and discharge cardiac medication and the use of investigations, particularly thyroid function tests and echocardiography. The heart rate on discharge, number cardioverted either during the admission or after discharge and the number given warfarin and aspirin were recorded.

One hundred and forty-seven patients (aged 38-96, mean age 76 years and 52% male) were admitted in AF 165 times out of the 1637 admissions over the study period (a prevalence of 10.4%, 95% CI 8.6-11.5%). The main causes of admission were heart failure (23%), pneumonia or sepsis (17%), cerebrovascular accident (CVA) or transient ischaemic attack (TIA) (14%) and ischaemic heart disease (11%). Past medical history included hypertension (46%), ischaemic heart disease (39%), congestive heart failure (58%), valvular heart disease (12%), chronic obstructive airways disease (24%), CVA, TIA or thromboembolic event (24%) and diabetes (17%). Thyroid function tests were performed in 50% of patients and echocardiograms in 38%. Heart rate control at discharge could not be assessed, as this was not recorded prior to any patient's discharge. Seventy-eight per cent of patients were discharged on digoxin but only 29% on drugs that control the heart rate with exercise. Five patients out of 11 considered for cardioversion had a successful cardioversion in hospital and two were later cardioverted as outpatients. Twenty-eight per cent were discharged on warfarin, 33% on aspirin and one patient on both. Fifty-two per cent were considered to have contraindications to warfarin therapy. Prescribing rates for warfarin did not vary according to the patients' clinical risk for thromboembolism.

AF is a common comorbid condition in the acute general medical ward. Standard investigations were under-utilised. Attention needs to be paid to the recording and control of heart rate at rest and on exercise. Cardioversion is considered infrequently. This patient group had a high risk for thromboembolism and after excluding the large group in whom warfarin was contraindicated, warfarin was still under-utilised.