Sudden-Death Risk Double for Blacks vs Whites in Cohort Study

Marlene Busko

July 28, 2015

LOS ANGELES, CA — Compared with white individuals who had a sudden cardiac arrest, black individuals were about 6 years younger and more likely to have hypertension, diabetes, renal insufficiency, congestive heart failure, left ventricular hypertrophy, and a longer QT interval on ECG, researchers report[1].

The study, by Dr Kyndaron Reinier (Cedars-Sinai Medical Center, Los Angeles, CA) and colleagues, based on the Oregon Sudden Unexpected Death Study (SUDS), was published July 20, 2015 in Circulation.

It also showed that twice as many blacks as whites of the same gender had a cardiac arrest during the past decade. This is believed to be "the first effort to extend beyond simple assessments of [cardiac disease] burden in blacks," senior author Dr Sumeet S Chugh (Cedars-Sinai Medical Center) told heartwire from Medscape.

"On average, 90% [of people with sudden cardiac arrest] will die within 10 minutes of having an episode, despite all the efforts made to perform emergency resuscitation," he pointed out. Thus, "the only real way to make an impact is to predict and prevent this devastating condition before it happens." The current preliminary study provides some clues and suggests that blacks may benefit from different preventive efforts.

It was "disconcerting" to find that sudden cardiac death manifests at a younger age in blacks and that rates of cardiac arrest in black women are higher than those of white men or white women, he added. "If I were to hypothesize about the possible explanations, these differences could be related to . . . genetic features, social and cultural habits, access to preventive healthcare, or more likely a combination of these," Chugh said.

Young Blacks, Black Women at Higher Risk

Each year, more than 300,000 in individuals living in the community and more than 200,000 hospitalized individuals die from sudden cardiac arrest, yet very little is known about possible racial differences, Chugh said.

The researchers identified 179 blacks and 1745 whites in the SUDS cohort from the metropolitan Portland area who met criteria for an episode of sudden cardiac arrestt—defined as a sudden unexpected condition due to cardiac causes and not trauma, drug overdose, or chronic terminal illness—from February 1, 2002 through January 31, 2012.

Most cardiac arrests occurred in adults over age 65. The circumstances were similar for blacks and whites: the average response time was 6 to 7 minutes, and most cases (68%) occurred at home. Both races had similar rates of documented coronary artery disease or left ventricular dysfunction and similar rates of medication use. There were no significant differences by race in preventive medications (other than slightly more anticoagulant use in whites).

After adjustment for age, the incidence of cardiac arrest in adults over age 18 was twofold higher in blacks than whites. There were 175 cardiac arrests per 100,000 black men, 84 per 100,000 white men, 90 per 100,000 black women, and 40 per 100,000 white women.

At the time of the cardiac arrest, compared with whites, blacks were younger (mean age 61 vs 67) and more likely to have diabetes (52% vs 33%, P <0.0001), hypertension (77% vs 65%, P=0.006), and chronic renal insufficiency (34% vs 19%, P<0.0001).

Blacks were also more likely to have congestive heart failure (43% vs 34%, P=0.04) and left ventricular hypertrophy (77% vs 58%, P=0.02) and on average had a longer QT interval (466 vs 453 ms, P=0.03).

In the subset patients who died from cardiac arrest and had an autopsy (blacks with a mean age of 42 and whites with a mean age of 47), blacks had less significant coronary stenosis and less evidence of an old infarction, but a somewhat higher proportion had hypertrophic cardiomyopathy.

"It is always difficult to generalize from a population of approximately one million to the rest of the United States," Chugh said. However, the gender split and the higher cardiovascular mortality in blacks are consistent with previous findings.

If further research confirms the different clinical features in blacks and whites who have sudden cardiac arrest, this "may provide new opportunities to lower the significant [sudden cardiac arrest] burden in blacks compared with other racial groups," Reinier and colleagues conclude.

Reinier and Chugh have no relevant financial relationships. Disclosures for the coauthors are listed in the article.

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