Researchers have found that the risk of sudden cardiac death is the highest in the period of 30 days after a heart attack. The study by researchers at the Veterans Affairs Medical Center in Minneapolis and Mayo Clinic in Rochester, Minn., shows that this short period plays a crucial role in the long term survival and health of patients.

The researchers examined medical records of 2997 people for a five year period. The average age of the participants was 67 years and they all had survived a heart attack between 1970 and 2005. The researchers found that in the 30 day period after the heart attack, 282 or 24 % of the patients had died. Out of the patient’s who made it past the 30 day period only 1 % died.

The researchers said the sudden death in the 30 day period was four times higher than expected while the rate was far lower than expected in the post 30 day period.

Reported in the Journal of the American Medical Association the researchers said, "Among 30-day survivors, the risk of sudden cardiac death declines rapidly, but it is markedly increased by the occurrence of heart failure during follow-up."

Although sudden deaths declined by over 40 % in the past 25 years, the cumulative incidence of sudden cardiac death in the first 30 days was four times higher than expected.

According to the study, these findings "underscore the importance of continued surveillance" of heart attack patients, and "the importance of evidence-based therapy" for these patients is evident. It is important to continue to monitor heart attack patients after the initial heart attack because complications can still occur later.