Ethnic Differences in Sudden Cardiac Arrest
Some studies suggest that African Americans (AA) have a higher incidence of sudden cardiac arrest (SCA) and worse survival than European Americans (EA). Ethnic differences in the circumstances and outcomes of SCA have not been well explored and have yielded inconsistent results. We therefore examined ethnic differences in patient characteristics, medical morbidities, arrest circumstances, medical care, and outcomes among SCA cases of European, African, and Asian descent in Seattle, Washington.
Out of hospital arrests in the greater Seattle area were identified by paramedics between 1988 and 2009, as part of the Cardiac Arrest Blood Study (CABS) Repository. Out of hospital arrest cases due to non-cardiac etiology were excluded. Ethnicity was ascertained by paramedic incident reports, hospital medical records and death certificates. Cases were linked to hospitalization records and geographic information systems data. Logistic regression analysis was used to examine the outcomes of successful resuscitation and survival to hospital discharge in 3 ethnicities, with EA as the reference group. Multinomial logistic regression analysis was used to examine predictors of the three different presenting rhythms: ventricular fibrillation (VF), pulseless electrical activity (PEA) and asystole, using VF as the reference group.
The cohort of SCA cases included 3551 EA, 440 AA, and 297 Asians (AS). AA cases were younger than the other two ethnic groups. On average, both AA and AS had lower education and lower income relative to EA (p<0.0001). Fewer AA had atrial fibrillation diagnosed during past hospitalizations (p<0.0001), but, along with AS, a larger proportion had previous diagnoses of hypertension, diabetes mellitus, and renal disease during hospitalizations compared with EA cases (p<0.0001). At the time of cardiac arrest, African and Asian-descent individuals were less likely to have a witnessed arrest or receive bystander CPR compared with European-descent SCA cases. AA were more likely to be found in PEA and AS were more likely to be found in asystole compared with EA cases. Resuscitation duration was the same in all 3 groups. Survival to hospital admission and discharge was similar in the 3 ethnicities (multivariate adjusted OR 1.10, 95% CI 0.79-1.54 for AA vs. EA, p=0.56; OR 1.33, 95% CI 0.86-2.05, p=0.20 for AS vs. EA). Moreover, among VF survivors, there was no statistically significant difference in the proportion of those who received coronary artery bypass graft (CABG) or implanted cardioverter defibrillator (ICD) prior to hospital discharge. Given the strong association of initial presenting rhythm with outcome, patient characteristics and clinical factors associated with VF, PEA, and asystole as presenting rhythm were explored in adjusted analyses. Compared with those presenting in VF, those presenting in PEA were more likely to be of African descent and less likely to receive bystander CPR (OR 1.54, 95% CI 1.15-2.07, p=0.004; OR 0.60, 95% CI 0.49-0.72, p<0.0001 respectively), and those in asystole were more likely to be of Asian descent (OR 1.53, 95% CI 1.10-2.13, p=0.01).
While other studies have shown higher mortality in AA than in EA individuals with SCA, in Seattle, with one of the country's most effective emergency medical care systems, we did not detect a difference in survival between European-, African- and Asian-descent individuals. Nearly 25% of SCA cases of all 3 ethnicities that presented with VF survived to hospital discharge. There is, however, a difference by ethnicity in presenting rhythm, with more PEA among AA and more asystole among AS SCA cases.