Sudden cardiac death—when death occurs within a very short period of time after the onset of heart attack symptoms—accounted for most of the cardiac and non-AIDS natural deaths seen in a chart review of people living with HIV receiving care at San Francisco General Hospital (SFGH), according to a new report published May 15 in the Journal of the American College of Cardiology.

The study also noted that the risk of sudden cardiac death among people living with HIV was 4.5 times the rate in San Francisco’s general population—a finding that has made media headlines. It is important to note, however, that the study was retrospective in design, specific to one city and didn’t include an HIV-negative control group, thus it is difficult to draw firm conclusions regarding the relative and absolute increases in the risk of sudden cardiac death among people living with HIV.

Led by Zian Tseng, MD, an associate professor of medicine in the University of California at San Francisco’s Department of Cardiology, a team of researchers sifted through the medical records—including death certificates and paramedic reports, and interviews with family members, doctors and other clinicians—of 2,680 people living with HIV who received care at SFGH between April 2000 and August 2009.

In an accompanying news announcement, Tseng explained he was interested in studying the link between HIV and sudden cardiac death after noticing many cases of people living with the virus dying suddenly. “I wondered if there was some sort of connection here,” he said.

Patients were followed for an average of 3.7 years; 230 deaths were reported in the group. One hundred thirty-one (57 percent) were AIDS related. Thirty (13 percent) of the deaths met the criteria for sudden cardiac death. Twenty-five (11 percent) of the deaths were due to other non-AIDS-related diseases, and 44 (19 percent) were due to drug overdoses, suicides or unknown causes.

Of the 35 cardiac-related deaths in the group, 30 (86 percent) met the criteria for sudden cardiac death.

Based on the sudden cardiac death rates in the general San Francisco population—using general health statistics, not the medical records of a well-matched HIV-negative control group in the study—Tseng and his colleagues calculated that there should have only been 6.73 sudden cardiac deaths in their HIV medical chart reviews. This translated into a 4.46-fold increase in the risk of sudden cardiac death.

SFGH patients who died of sudden cardiac death tended to be somewhat older (49 versus 45) than those who died of AIDS, have higher CD4 counts (312 versus 87 cells) and have lower viral loads (6,300 versus 63,000 copies).  These findings, the researchers argue, indicate that people living with HIV are at risk for sudden cardiac death even in the setting of relatively mild HIV disease.

Still, a number of risk factors were documented by the researchers. Compared with those who died of AIDS during the follow-up period, those who experienced sudden cardiac death were more likely to have had a previous heart attack (17 versus 1 percent), enlargement of the heart (cardiomyopathy; 23 versus 3 percent), congestive heart failure (30 versus 9 percent) and abnormal heart rhythm (arrhythmia; 20 versus 3 percent).

“Given that cardiac symptoms were common in victims of [sudden cardiac death], aggressive primary prevention of [cardiovascular disease] should be considered in HIV-infected patients, especially those with traditional risk factors,” Tseng and his colleagues conclude. “As we seek to reduce mortality in an aging HIV-infected population, greater attention must be directed to the mechanisms underlying [sudden cardiac death], with the goal of identifying at-risk patients and ultimately preventing sudden death.”