Sudden Heart Death

Sudden cardiac death remains unexplained

/ Author:  / Reviewed by: Joseph V. Madia, MD

(RxWiki News) Sudden cardiac death is largely unexplained. Death can occur within minutes, leaving doctors scratching their heads. Unless a preexisting heart condition is discovered, the cause may never be known.

A new study being unrolled at the University of California, San Francisco’s Cardiac Electrophysiology Service hopes for the first time to discover the causes of those sudden deaths.

University researchers will work with the Office of the Chief Medical Examiner for the city and county of San Francisco to fully investigate every death by sudden cardiac event in San Francisco over a three-year period.

"Past heart disease could be a factor in sudden cardiac death."

In addition to finding out the underlying causes of those deaths, researchers hope to discover why it is more prevalent in some demographic populations, and whether it is too often inaccurately cited as a cause of death. The study will be funded with $1.9 million over five years from the National Institutes of Heath.

Researchers believe San Francisco will be ideal for the study because of its rich character and cultural composition. U.S. Census Bureau figures suggest San Francisco’s current level of ethnic diversity is where the national demographic will shift in about 30 years.

Sudden cardiac death affects about 295,000 people per year. Some ethnic populations are affected more often than others. African Americans, for example, suffer a rate nearly three times higher than Caucasians. Very little is known about the underlying causes or the differences in racial disparity.

Sudden cardiac death is defined by the American Heart Association as death resulting from an abrupt loss of heart function, or cardiac arrest, in which the victim may or may not have diagnosed heart disease.

Dr. Zian H. Tseng, M.D., assistant professor of medicine in UCSF’s Cardiac Electrophysiology Service, said finding the causes are critical in understanding who is at highest risk for the disease and which medical interventions, like defibrillators, are likely to be most effective.

Dr. Tseng said one reason the study is needed is because the disease has not been widely researched and most known knowledge is nearly 30 years old, was derived mostly from homogeneous Caucasian populations, and likely included patients who died of reasons other than sudden cardiac death. Additionally, autopsies are performed in only 10 to 15 percent of cases, which makes a lot of assumptions, Dr. Tseng said.

During the second phase of the study, the team will build a database of the cases, including information about heart tissue and clinical data from the deceased subjects’ past medical records.

Dr. Tseng will look at the heart, and analyze factors such as scarring, weight and thickness of heart walls, as well as the presence of other conditions including diseases of the heart valves. Information from autopsies previously performed by the medical examiner’s office on individuals who died from causes not related to the heart  will be compared against the data.

The World Health Association considers sudden cardiac death as the collapse within one hour of symptom onset, if witnessed, or last seen alive 24 hours before collapse, if not witnessed.

Dr. Tseng suspects that the very definition of sudden cardiac death is inaccurate, allowing deaths from unknown causes – such as hemorrhage, vascular aneurysm or stroke – to be erroneously lumped into the sudden-death category.

Reviewed by: 
Review Date: 
June 17, 2011
Last Updated:
June 19, 2011