Atrial fibrillation and ethnicity

Atrial fibrillation and ethnicity: the known, the unknown and the paradox

Current understanding of the pathophysiology and epidemiology of atrial fibrillation (AF) is based primarily on studies in White populations of European ancestry with limited data on the non-White populations. Many traditional and novel risk factors for AF have been already established. However, little is known about the differential impact of these AF risk factors in non-White versus White populations. Few studies have compared the prevalence and incidence of AF in Black versus White individuals, and still fewer extended this comparison to other races and ethnicities. These few studies consistently reported that Black individuals have lower AF burden compared with their White counterparts. These findings are not consistent with the reported high stroke rates in Black populations and the strong association between stroke and AF. In this perspective we argue that differential AF underascertainment among different racial and ethnic groups may be the key in explaining this paradox of racial/ethnic distribution of AF. Results from recent publications suggest that Black individuals would have higher rates of AF if more sensitive AF detection methods are used. Although these findings do not reach the level of definitive evidence, they may support the need for rethinking the epidemiology of AF across races and ethnicities in the context of the limited methodology available to detect AF, as well as the questionable assumption that the ability to diagnose AF across different racial/ethnic groups is the same.

An 8-year follow-up study of acute admissions with heart failure in a multiethnic population

In 1994, we reported a cross-sectional survey of acute heart failure admissions to a city centre hospital serving a multiethnic population and found ethnic differences in aetiological factors and short-term (in-patient) mortality. We analysed long-term mortality data for this original survey cohort after 8 years' follow-up. At 8 years' follow-up, the total mortality was 90.5% amongst Europeans and 87.0% amongst non-Europeans (log rank test, P=0.0705). The non-European patients had significantly better survival at all time points until 6 years, after which the survival curves start to converge. In univariate analysis, age <75.6 years (that is, the median age of the whole cohort), use of beta-blockers, use of ACE inhibitors, and absence of atrial fibrillation were significantly associated with increased survival. In addition, patients who had had an echocardiographic examination had significantly prolonged survival when compared to those who did not. Using a Cox multiple regression analysis, age, renal impairment, atrial fibrillation, absence of echocardiography, absence of beta-blockers or ACE inhibitor use (and not ethnicity) remained significant predictors of mortality at 8 years. While this follow-up study has suggested that survival following admission for acutely decompensated heart failure is not different between different ethnic groups when corrected for age, it is clear from the younger age of heart failure patients from ethnic minority groups and the relatively high prevalence, that the burden of heart failure is greater in these populations. Future observational and therapeutic trials in heart failure should include sufficient numbers of participants from ethnic minority groups to ensure that the results can be applied to the population at risk.

Prospective Assessment after Pediatric Cardiac Ablation:. Demographics, Medical Profiles, and Initial Outcomes

INTRODUCTION

A multicenter prospective study was designed and implemented to assess the short- and longer-term results and risks associated with radiofrequency (RF) ablation in children.

METHODS AND RESULTS

Patients recruited for the study were aged 0 to 16 years with supraventricular tachycardia due to accessory pathways or AV nodal reentrant tachycardia (AVNRT), excluding patients with nontrivial congenital heart disease. A national registry also was established, and contributing centers were encouraged to enroll all pediatric patients, aged 0 to 21 years, undergoing ablation at their center. This report summarizes acute results of these procedures. For analysis, subjects were divided into three groups: the prospective cohort (n = 481), cohort-eligible registry participants (n = 504), and not cohort eligible registry participants (n = 1,776). Prospectively enrolled cohort patients were similar to cohort-eligible patients in terms of demographic and other patient characteristics. Overall success rates for RF ablation were high (95.7%), with higher success rates for left-sided and particularly left free-wall pathways (97.8%) than right free-wall pathways (90.8%). Complications of both electrophysiologic study and RF ablation were infrequent (4.2% and 4.0%, respectively), and there were no deaths. AV block was uncommon overall (1.2%) and was limited to ablation in AVNRT (2.1%) and septal accessory pathways (3.0%).

CONCLUSION

Despite the multicenter and prospective design, the study demonstrates high success rates and low complication rates, which are comparable to prior single-center retrospective studies. These results may serve as the current best benchmark for expected results in the pediatric population, aged 0 to 16 years, both in terms of acute success rates and the occurrence of complications.

Heart failure-the importance of ethnicity

Heart failure is a major public health problem in the Western world. Aetiological factors involved in its development include hypertension, diabetes, and ischaemic heart disease--all of which differ in prevalence, and possibly mechanism, between patients of differing ethnicity. Unfortunately, epidemiological and therapeutic trials have involved almost exclusively white populations, and evidence from these trials cannot necessarily be assumed to be generalisable to populations that include high proportions of patients from other ethnic origins. This review will discuss the mechanistic and therapeutic differences that exist in heart failure between those of European origin, and patients from the major ethnic minority groups of the UK.

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

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.