Survival in South Asian and White European patients after acute myocardial infarction

Ethnic differences between South Asians and White Caucasians in cardiovascular disease-related mortality in developed countries: a systematic literature review

BACKGROUND

Cardiovascular disease is the leading cause of death worldwide, with significantly worse mortality-related outcomes in ethnic minorities in developed countries. A systematic literature review and meta-analysis of observational studies was conducted to investigate cardiovascular disease-related mortality inequalities between South Asian and White Caucasian ethnic groups.

METHODS

Published studies on mortality between South Asians and Whites in developed countries were retrieved from MEDLINE, PubMed, Embase, Web of Science, and grey literature sources (inception-April 2021) and critically appraised using the Quality in Prognosis Studies tool. Bayesian random-effects meta-analyses were performed for both primary and secondary outcomes. Heterogeneity was determined using the I² statistic.

RESULTS

Of the 9879 studies screened originally, 41 were deemed eligible. A further 3 studies were included via the later search. Of these, 15 reported cardiovascular disease-related mortality, 23 reported all-cause mortality, and 6 reported both. The meta-analysis results showed that South Asians had a significantly increased risk of cardiovascular disease mortality compared to Whites (risk ratio = 1.32; 95% credible interval = 1.14 to 1.54) and a decreased risk of all-cause mortality (risk ratio = 0.95; 95% credible interval = 0.83 to 1.12).

DISCUSSION

South Asians had statistically significantly higher odds of cardiovascular disease-related mortality compared to Whites, but not for all-cause mortality. Risk of bias was a serious concern mainly due to a lack of confounders being reported.

SYSTEMATIC REVIEW REGISTRATION

PROSPERO: CRD42021240865.

Leveraging Clinical Digitized Data to Understand Temporal Characteristics and Outcomes of Acute Myocardial Infarctions at a Tertiary Care Medical Centre in Pakistan from 1988–2018 – Methods and Results

Background and Objective:

Few data exist on trends in acute myocardial infarction (AMI) patterns spanning recent epidemiological shifts in low middle-income countries (LMICs). To understand temporal disease patterns of AMI characteristics and outcomes between 1988–2018, we used digitized legacy clinical data at a large tertiary care centre in Pakistan.

Methods:

We reviewed digital health information capture systems maintained across the Aga Khan University Hospital and obtained structured elements to create a master dataset. We included index admissions of patients >18 years that were discharged between January 1, 1988, and December 31, 2018, with a primary discharge diagnosis of AMI (using ICD-9 diagnoses). The outcome evaluated was in-hospital mortality.

Clinical characteristics derived from the electronic database were validated against chart review in a random sample of cases (k 0.53–1.00).

Results:

The final population consisted of 14,601 patients of which 30.6% (n = 4,470) were female, 52.4% (n = 7,651) had ST elevation MI and 47.6% (n = 6,950) had non-ST elevation MI. The median (IQR) age at presentation was 61 (52–70) years. Overall unadjusted in-hospital mortality was 10.3%. Across the time period, increasing trends were noted for the following characteristics: age, proportion of women, prevalence of hypertension, diabetes, proportion with NSTEMI (all p_trend < 0.001). In-hospital mortality rates declined significantly between 1988–1997 and 2008–2018 (13.8% to 9.2%, p < 0.001).

Conclusions:

The patterns of AMI have changed over the last three decades with a concomitant decline in in-hospital mortality at a tertiary care centre in Pakistan. Clinical digitized data presents a unique opportunity for gaining insights into disease patterns in LMICs.

Cardiovascular events and mortality in people with and without type 2 diabetes: An observational study in a contemporary multi-ethnic population

AIMS/INTRODUCTION

The aim of this study was to examine ethnicity-specific associations between type 2 diabetes mellitus and the risk of a cardiovascular disease (CVD) event as well as risk of specific CVD phenotypes in England.

METHODS

We obtained data from the Clinical Practice Research Datalink for adults with and without type 2 diabetes mellitus diagnosed 2000-2006. The outcome was the first CVD event during 2007-2017 and the following components: aortic aneurysm, cerebrovascular accidents, heart failure, myocardial infarction, peripheral vascular disease and other CVD-related conditions. Flexible parametric survival models were used to estimate ethnicity-specific adjusted hazard ratios.

RESULTS

A total of 734,543 people with and without type 2 diabetes mellitus (29,847; 4.1%) were included; most were of white ethnicity (93.0% with and 92.3% without type 2 diabetes mellitus) followed by South Asian (3.2 and 4.6%). During a median follow-up period of 11.0 years, 67,218 events occurred (6,156 in individuals with type 2 diabetes mellitus). Type 2 diabetes mellitus was associated with a small increase in CVD events (adjusted hazard ratio 1.06, 95% confidence interval 1.02-1.09) in individuals of white ethnicity; whereas the adjusted hazard ratios were considerably higher in individuals of South Asian ethnicity (1.28, 95% confidence interval 1.09-1.51), primarily due to an increased risk of myocardial infarction (1.53, 95% confidence interval 1.08-2.18).

CONCLUSIONS

Despite universal access to healthcare, there are large disparities in CVD outcomes in people with and without type 2 diabetes mellitus. Other non-traditional risk factors might play a role in the higher CVD risk associated with type 2 diabetes mellitus in individuals of South Asian ethnicity.

Evidence for reduced susceptibility to cardiac bradycardias in South Asians compared with Caucasians

Objectives

To investigate ethnic differences in susceptibility to bradycardias in South Asian and white European patients in the UK by determining rates of permanent pacemaker (PPM) implantation for sinus node dysfunction (SND) and atrioventricular block (AVB) in each ethnic group.

Methods

We carried out a retrospective cohort study into new PPM implantation during the period from 1 May 2006 to 31 March 2014, in patients of South Asian and Caucasian ethnicity resident in Leicestershire, UK. Numbers of individuals at risk in each ethnic group were derived from UK National Census data of 2011. Crude, and age-standardised incidence rates and risk ratios per 1000 population of PPM implantation were calculated for Caucasians and South Asians.

Results

During the study period, 4883 individuals from the Leicestershire population of 980 328 underwent PPM implantation, a cumulative implantation rate of 4.98/1000 population. The population cumulative PPM implantation rate for SND was 1.74/1000, AVB 2.83/1000 and other indications 0.38/1000 population. The crude incidence in Caucasians (6.15/1000 population) was higher than in South Asians (1.07/1000 population) and remained higher after age standardisation (5.60/1000 vs 2.03/1000, P<0.001). The age-standardised cumulative PPM implantation rates were lower in South Asians for both SND (0.53/1000 in South Asians; 1.97/1000 in Caucasians, P<0.001) and AVB (1.30/1000 in South Asians; 3.17/1000 in Caucasians, P<0.001). Standardised risk ratios (95% CI) for PPM implantation in South Asians compared with Caucasians for all pacing indications, SND and AVB were 0.36 (95% CI 0.36 to 0.37), 0.27 (95% CI 0.27 to 0.28) and 0.41 (95% CI 0.41 to 0.42), respectively.

Conclusions

Rates of PPM implantation are lower in South Asians residing in the UK, compared with Caucasians. This observation raises the possibility of lower inherent susceptibility to bradycardias in South Asians compared with Caucasians. Studies aimed at identifying underlying mechanisms, including possible genetic differences, are warranted.

Ethnic differences in case fatality following an acute ischaemic heart disease event in New Zealand: ANZACS-QI 13

BACKGROUND

The aim of this study was to investigate ischaemic heart disease (IHD) case fatality in high-risk ethnic populations in New Zealand.

DESIGN

This is a national data-linkage study using anonymised hospitalisation and mortality data.

METHODS

Linked individual patient data were used to identify 35-84-year-olds who experienced IHD events (acute IHD hospitalisations and/or deaths) in 2009-2010. Subjects were classified as: (i) hospitalised with IHD and alive at 28 days post-event; (ii) hospitalised with IHD and died within 28 days; (iii) hospitalised with a non-IHD diagnosis and died from IHD within 28 days; or (iv) died from IHD but not hospitalised. Multinomial logistic regression was used to estimate the proportion of people in each group, as well as overall 28-day case fatality, adjusted for ethnic differences in demographic and comorbidity profiles.

RESULTS

A total of 26,885 people experienced IHD events (11.3% Māori, 4.0% Pacific and 2.5% Indian); 3.3% of people died within 28 days of IHD hospitalisations, 5.1% died of IHD within 28 days of non-IHD hospitalisations and 13.0% died of IHD without any recent hospitalisation. Overall adjusted case fatality was 12.6% in Indian, 20.5% in European, 26.0% in Pacific and 27.6% in Māori people. Compared to Europeans, the adjusted odds of death were approximately 50% higher in Māori and Pacific people and 50% lower in Indians, regardless of whether they were hospitalised.

CONCLUSIONS

Major ethnic inequalities in IHD case fatality occur with and without associated hospitalisations. Improvements in both primary prevention and hospital care will be required to reduce inequalities.

Racial Differences in Electrocardiographic Characteristics and Prognostic Significance in Whites Versus Asians

Background

Racial differences in electrocardiographic (ECG) characteristics and prognostic significance among Whites and Asians are not well described.

Methods and Results

We studied 2677 White Framingham Heart Study participants (57% women) and 2972 Asian (64% women) Singapore Longitudinal Aging Study participants (mean age 66 years in both) free of myocardial infarction or heart failure. Racial differences in ECG characteristics and effect on mortality were assessed. In linear regression models, PR interval was longer in Asians compared with Whites (multivariable‐adjusted β±SE 5.0±1.4 ms in men and 6.6±0.9 ms in women, both P<0.0006). QT interval was shorter in Asian men (β±SE −6.2±1.2 ms, P<0.0001) and longer in Asian women (β±SE 3.6±0.9 ms, P=0.02) compared to White men and women, respectively. Asians had greater odds of having ECG left ventricular hypertrophy (LVH) compared with Whites (odds ratio [OR] 3.56, 95% confidence interval [CI] 1.36–9.35 for men, OR 1.93, 95% CI 1.35–2.76 for women, both P<0.02). Over a mean follow‐up of 11±3 years in Framingham and 8±3 years in Singapore, mortality rates were 24.5 and 13.4 per 1000 person‐years among Whites and Asians, respectively. In Cox models, the presence of LVH had a greater effect on all‐cause mortality in Asians compared with Whites (hazard ratio [HR] 2.66, 95% CI 1.83–3.88 vs HR 1.30, 95% CI 0.90–1.89, P for interaction=0.02).

Conclusion

Our findings from two large community‐based cohorts show prominent race differences in ECG characteristics between Whites and Asians, and also suggest a differential association with mortality. These differences may carry implications for race‐specific ECG reference ranges and cardiovascular risk.