According to Dr. Chugh, the findings reinforce the importance of a healthy lifestyle for black patients to avoid developing certain sudden cardiac arrest risk factors.
The study was led by Dr. Sumeet S. Chugh, associate director of the Cedars-Sinai Heart Institute in Los Angeles, CA, who examined data on residents in the metropolitan area of Portland, OR, who had sudden cardiac arrests between 2002 and 2012.
A cardiac arrest is when the heart's electrical system malfunctions, preventing the heart from pumping blood around the body. Sudden cardiac arrests are a major cause of death in the US, leading to around 300,000-350,000 deaths a year - around 50% of all cardiovascular deaths.
According to the authors of the study, there is little information regarding sudden cardiac arrest in nonwhite racial groups in the US. Previous studies carried out 2-3 decades ago estimated a higher incidence of cardiac arrests among black people than white people, but these studies were limited by only assessing cardiac arrest incidence through narrow sets of parameters.
For the study, the researchers utilized data from the Oregon Sudden Unexpected Death Study (SUDS) to compare the medical histories of sudden cardiac arrest patients by race. The Oregon SUDS is an ongoing community-based study that uses multiple sources to ascertain the number of out-of-hospital sudden cardiac arrests occurring in the Portland area.
The researchers collected data for a total of 1,745 white residents and 179 black residents that experienced sudden cardiac arrest during the study period.
They found that black residents were more than twice as likely as white people to experience sudden cardiac arrest, with 175 black men and 90 black women per 100,000 experiencing sudden cardiac arrest compared with 84 white men and 40 white women per 100,000.
At the time of sudden cardiac arrest, the majority of black people were younger than 65 while the majority of white people were older than 65. On average, black people were more than 6 years younger than white people when experiencing sudden cardiac arrest.
Clinicians should be aware of a 'broader spectrum of risk factors'
In addition, a number of well-established risk factors for cardiovascular disease and noncoronary heart problems were found to be more prevalent among black people than white people:
- Chronic kidney failure (34% compared with 19%)
- Diabetes (52% compared with 33%)
- High blood pressure (77% compared with 65%)
- Congestive heart failure (43% compared with 34%)
- Left ventricular hypertrophy (77% compared with 58%).
However, both black and white people who experienced sudden cardiac arrest were found to have the same rates of coronary artery disease, a condition that has long been considered the greatest predictor of sudden cardiac arrest risk.
As the study found that black people had a higher prevalence of noncoronary cardiac risk factors for sudden cardiac arrests, it suggests identifying a broader spectrum of risk factors could help clinicians lower the sudden cardiac arrest burden in black people compared with other racial groups.
Dr. Chugh says:
"Cardiac arrest is recognized by the 'bad company' it keeps, so the mantra has been: prevent coronary artery disease, prevent sudden cardiac death. As health care professionals, we should be aware of a broader spectrum of risk factors for our black patients. If we only focus on reducing coronary artery disease, we are unlikely to offer them the same benefit we offer white patients."
Due to the small number of black control subjects available to the researchers, they were unable to include analyses comparing black and white cases to black and white controls. The researchers state that, as a result, further investigation is required to find out whether these risk factors are independently associated with sudden cardiac arrest.
Going forward, the researchers believe their study should be replicated in other communities. To date, they have begun to expand their investigations to Ventura County, CA - a community with a large Hispanic population.