Admissions with atrial fibrillation in a multiracial population in Kuala Lumpur, Malaysia

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Abstract

Background: There are established differences in cardiovascular disease in different racial groups. Worldwide, the literature regarding the clinical epidemiology of atrial fibrillation in non-white populations is scarce. Objectives: To document the prevalence of atrial fibrillation (AF) in the multiracial population of Malaysia, and to describe the clinical features and management of these patients. Setting: Busy city centre general hospital in Kuala Lumpur, Malaysia, over a 1-month period. Subjects: One-thousand four hundred and thirty-five acute medical admissions, of whom 40 patients (2.8%) had AF. Results: Of 1435 acute medical admissions to Kuala Lumpur General Hospital over the 4-week study period, 40 had AF (21 male, 19 female; mean age 65 years). Of these, 18 were Malay, 16 Chinese and six Indian. Nineteen patients had previously known AF (seven with paroxysmal AF) and 21 were newly diagnosed cases. The principal associated medical conditions were ischaemic heart disease (42.5%), hypertension (40%) and heart failure (40%). Dyspnoea was the commonest presentation, whilst stroke was the cause of presentation in only two patients. Investigations were under-utilised, with chest X-ray and echocardiography in only 62.5% of patients and thyroid function checked in 15%. Only 16% of those with previously diagnosed AF were on warfarin, with a further three on aspirin. Anticoagulant therapy was started in 13.5% of patients previously not on warfarin, and aspirin in 8%. Records of contraindications to warfarin were unreliable, being identified in only 25%. For those with known AF, 58% were on digoxin. For new onset AF, digoxin was again the most common rate-limiting treatment, initiated in 38%, whilst five patients with new onset AF were commenced on amiodarone. DC cardioversion was not used in any of the patients with new onset AF. Conclusion: Amongst acute medical admissions to a single centre in Malaysia the prevalence of AF was 2.8%. Consistent with previous similar surveys in mainly western (caucasian) populations, standard investigations in this Malaysian cohort were also inadequate and there was underuse of anticoagulation, medication for ventricular rate control and cardioversion to sinus rhythm.

Introduction

Atrial fibrillation (AF) is the most common chronic cardiac arrhythmia [1]. The annual incidence per 1000 person years has been reported at 3.1 cases in men and 1.9 cases in women age 55–64 years, rising to 38.0 and 31.4 cases in men and women in the 85–94 age group [2]. Risk factors for AF include male sex, advancing age, ischaemic heart disease, hypertension, valvular heart disease, heart failure, and diabetes [2]. Atrial fibrillation is also an important risk factor for stroke, resulting in a 3- to 5-fold excess risk [3], [4]. Nevertheless, the information on epidemiology, risk factors, treatment and complications of AF are largely confined to studies in Western (Caucasian) populations.

Although there are recognised differences in cardiovascular disease and stroke between ethnic groups, epidemiological data on AF in non-white populations are very limited. Some racial differences in the prevalence of AF were suggested by the Cardiovascular Health Study, in which 5% of the study population were black [5], where the latter ethnic group had half the age-adjusted risk of developing AF compared with whites (RR 0.47, 95% C.I. 0.22–1.01). In the Northern Manhattan Stroke Study, of those patients presenting with ischaemic stroke, AF was more common in whites (29%) than in either black (11%) or hispanic (11%) patient groups [6]. In our previous survey of acute medical admissions with AF to a city centre hospital in Birmingham, UK, serving a multiethnic population, only 4% were black and 9% were of Indo-Asian origin [7]. The most common risk factor in Afro-Caribbean patients was hypertension, whereas Indo-Asian patients were more likely to have ischaemic heart disease and were younger than black or white patients. Our general practice-based survey in the west Birmingham AF project found the prevalence of AF to be only 0.6% amongst Indo-Asians, who as an ethnic group comprised 65% of the 25 051 general practice population surveyed [8]. Previous small studies have also estimated the prevalence of, and risk factors associated with AF in India, Africa, Japan, Thailand and Hong Kong [9], [10], [11], [12], [13].

AF is common amongst acute medical admissions, and in one USA series, AF accounted for 34.5% of patients admitted with a rhythm disturbance [14]. In view of the lack of information on AF in non-caucasian populations, the aim of the present survey was to study the prevalence of AF in the multiracial population of Malaysia, and to describe the clinical features and management of these patients.

Section snippets

Patients and methods

We conducted a prospective survey of acute medical admissions to a busy city centre general hospital in Kuala Lumpur, Malaysia over a 4-week period (15th May 2000 to 13th June 2000). This hospital is the main government hospital serving a 1.4 million catchment population of the city of Kuala Lumpur. The multiracial population of Malaysia consists primarily of three main ethnic groups: Malays, Chinese, and Indians.

During the study period, acute admissions were screened for AF. Subjects were

Results

There were a total of 1435 adult acute medical admissions over the 4-week study period. Of these, 40 patients (2.8%; 21 male, mean age 65 years, S.D. 10.3, range 28–93 years) of these had AF: 12 (30%) patients were known to have chronic AF, seven patients (17.5%) had paroxysmal AF and 21 patients (52.5%) patients were newly diagnosed. Of the AF patients, 18 were Malay (44%), 16 were Chinese (40%) and six were Indian (16%).

Discussion

The worldwide literature on AF in non-white groups is limited. In the present study which was based in a busy city centre general hospital in Kuala Lumpur, Malaysia, we found an overall prevalence of AF amongst acute medical admissions of 2.8%, which is lower than reported in similarly conducted previous studies, looking at acute medical admissions in the UK [7], [15].

The prevalence of AF worldwide has been reported to be as high as 22% in one study on sick elderly inpatients, or as low as 0.1%

Acknowledgments

We thank the staff of Kuala Lumpur General Hospital for assistance in conducting our survey.

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