Caucasians have a higher incidence of an out-of-hospital cardiac arrest but risk of death is higher in African Americans.

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Karuppiah Arunachalam

There is a lack of sufficient data about the effect of racial differences on outcomes following an out-of-hospital cardiac arrest. Therefore, Karuppiah Arunachalam and colleagues—using results from the national inpatient sample (NIS) database—sought to determine what role (if any) race played in the risk of mortality following an out-of-hospital cardiac arrest.1 In this commentary, Arunachalam reviews the data from the study and discusses its implications.

In our study, we identified a total of 85,988 patients who had an out-of-hospital cardiac arrest between 2012 and 2013. We found that the overall incidence was higher in males as compared with females (56.5% vs. 43.5 %, respectively; p<0.0001). However, mortality was significantly higher in the female population than in the male population (51.9 % vs. 48.6%; p<0.0001). This finding support those of a retrospective study by Bosson et al, which showed that males have better survival following an out-of-hospital cardiac arrest and increased access to interventions and invasive procedures compared with females.2

We noted a similar disparity between incidence and mortality among Caucasians and African Americans. While the former group had a significantly higher incidence of an out-of-hospital cardiac arrest (63.8% vs. 16%; p<0.0001), the latter group had a 23% increased risk of dying after such an event (p<0.01 for the comparison).1 Galea et al also found evidence of substantial differences between African-Americans and Caucasians (of patients living in New York City).3

Health disparities between patients of different race result from multiple factors—including individual and behavioural factors, genetic factors, poverty, educational inequalities, environmental threats, and inadequate access to healthcare. On a population level, in the USA, African Americans generally have less access to healthcare and a higher incidence of obesity, smoking, hypertension and heart disease than do Caucasians.

Also, compared with Caucasians, African Americans tend to have a higher incidence of untreated heart disease, have an increased risk of hypertension, and receive significantly fewer cardiovascular procedures, treatments, and therapies (including aspirin, β blockers, reperfusion therapy, thrombolytic therapy, catheterisation, revascularisation and coronary artery bypass grafting).4 They are also less likely to receive bystander cardiopulmonary resuscitation (CPR) and their out-of-hospital cardiac arrest is less likely to be witnessed.5 Furthermore while there has been an overall trend towards increased use of internal cardioverter defibrillators (ICD) in all survivors of a sudden cardiac arrest, African American patients are still less likely than Caucasians to receive an ICD for primary prevention of sudden cardiac death.6 However, in our study, the African American population had higher mortality even after excluding patients with ICDs.

Aside from these factors, genetics may also have an impact. Researchers have found that African Americans have increased incidence of mutational variants of genes that code potassium rectifier channels, such as KCNQ1, KCNH2, KCNE1, and KCNE2.7 J-point elevation, which is commonly known as benign early repolarisation, is more prevalent in African Americans and is linked to ventricular fibrillation and polymorphic ventricular tachycardia.8

The differences in incidence and outcomes between different racial groups should be further investigated by randomised clinical trials to understand the context and reasons behind such differences.

References:

  1. Arunachalam et al. EP Europace 2017;19: iii195
  2. Kitamura et al. Eur Heart J 2010; 31: 1365–72.
  3. Galea et al. Am J Epidemiol 2007; 166 (5): 534–43
  4. Smedley et al. Washington, DC: National Academies Press 2003: 29–60.
  5. Becker et al. N Engl J Med 1993: 329: 600–06.
  6. Cummins et al. Ann Emerg Med 1997; 29: 647–49.
  7. Ackerman et al. Mayo ClinProc 2003; 78: 1479–87.
  8. Tereshchenko et al. Heart Rhythm 2012; 9: 1594–02.

Karuppiah Arunachalam is at Brown University, Rhode Island, USA. K Arunachalam et al’s study was presented at EHRA EUROPACE-CARDIOSTIM 2017 (18–21 June, Vienna, Austria). The senior author of the paper was Abhishek Maan, who is also at Brown University.

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