BOSTON, MASSACHUSETTS. About half of the 500,000 deaths occurring in the United States every year due to coronary heart disease happen suddenly. For half the victims of sudden cardiac death (SCD) death is the first indication that anything was wrong with their heart. A group of researchers from the Harvard Medical School, Massachusetts General Hospital, and Brigham and Women's Hospital now report the discovery of a marker that may predict the risk of SCD almost 10 years prior to an event actually occurring.
The researchers analyzed blood samples from 97 SCD victims and compared the results to those of 192
matched controls. All participants were part of the large Physicians' Health Study and had been followed
since 1982. The researchers observed a highly significant difference in the blood level of C-reactive protein
(CRP) between the two groups. The SCD victims had average CRP levels of 0.17 mg/dL (1.7 mg/L) as
compared to the controls at 0.10 mg/dL (1.0 mg/L). It was also clear that participants with CRP levels above
0.44 mg/dL (4.4 mg/L) had almost three times greater risk of SCD than did those with levels of 0.04 mg/dL
(0.4 mg/L) or less. Homocysteine and cholesterol levels were not significantly related to the risk of SCD
once the data had been adjusted for other cardiac death risk factors (hypertension, diabetes, smoking, etc.).
There was a slight, but statistically non-significant trend for a high ratio of total cholesterol to high-density
cholesterol (HDL) to be indicative of a higher SCD risk. Going from a ratio of 3.3 or less to a ratio of 6.3 or
more approximately doubled the risk, but this correlation became statistically insignificant once the other risk
factors were accounted for. The researchers conclude that testing for CRP levels may improve the
physician's ability to predict SCD and advise the patient to take "evasive" action.