The Risk of Sudden Cardiac Death is Highest in the Early Period Following a Heart Attack

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Heart attack and Cardiac Death

New research is needed to identify therapies and strategies to protect patients during this vulnerable time

Even with modern medical treatment, patients who have experienced a heart attack remain at increased risk for sudden death after they are discharged from the hospital. In an effort to better understand who to treat and when, researchers at Brigham and Women's Hospital (BWH), in collaboration with an international research team, studied sudden death in 14,609 men and women with a heart attack enrolled in the VALIANT Trial (Valsartan in Acute Myocardial Infarction Trial).

They found that the risk of sudden death was highest in the first 30 days following a heart attack, and that the risk declined rapidly with time. The risk of sudden death was particularly high in patients with reduced left ventricular (main heart pump) function. Researchers also found unexpectedly that patients with better left ventricular function were also at increased risk of dying suddenly during this early period. These findings suggest that new treatments focused on patients in that highest risk period could lead to a substantial saving of lives after a heart attack. Details are in the June 23, 2005 issue of the New England Journal of Medicine.

According to lead author Scott D. Solomon, MD, director of Noninvasive Cardiology at BWH, because sudden death is so catastrophic, particularly given today's known life-saving drugs and treatments, it is important to better understand the threshold of risk. "This study confirms that patients who have a decreased left ventricular ejection fraction after heart attack are at high risk of sudden death in the early period after an event. However, we also found that even patients with better cardiac function were also at risk during the early period. Although this risk of dying suddenly due to heart rhythm disturbances is greatest in the first few days after a heart attack - usually when the patient is in the hospital - we found that a substantial number of patients die suddenly and unexpectedly after hospital discharge. As we discharge patients earlier and earlier after heart attack, we need to consider this risk. While we currently have good long-term therapies for patients at high risk for sudden death, notably implantable defibrillators, the fact that this risk is very high early on, then declines, would support the development of short-term strategies that might lead to savings lives during this particularly high risk period."

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Researchers studied 14,609 patients, between December 1998 and June 2001, who were enrolled in the VALIANT Trial (Valsartan in Acute Myocardial Infarction Trial) - men and women with a median age of 67 years - with left ventricular dysfunction, heart failure or both after heart attack to assess the incidence and timing of sudden unexpected death in relation to left ventricular ejection fraction. Causes of death were classified as non-cardiovascular or cardiovascular, and cardiovascular deaths were further classified as sudden or due to heart attack, heart failure, stroke or other cardiovascular causes.

Of the 14,609 patients studied, 1,067 died suddenly or were resuscitated following a cardiac arrest (median time after heart attack was 180 days). The risk of sudden death or cardiac arrest was highest in the first 30 days after heart attack. Indeed, during the first month, the rate of sudden death or cardiac arrest was 1.4 percent per month, and dropped to one-tenth that after two years. Furthermore, the majority of patients who died suddenly during the first 30 days did so after hospital discharge. Those with lower left ventricular ejection fraction (more impaired heart function), diabetes and hypertension had a higher risk of sudden death or cardiac arrest.

According to the researchers, these data indicate that the risk of sudden death changes dynamically after a heart attack, and that even patients with higher ejection fraction may be at risk during this early period. Current guidelines recommend implantation of a defibrillator for patients with significantly reduced left ventricular function after a heart attack, but not until at least 30 days after the event. During this period, many patients who remain at high risk are unprotected.

"We need to consider therapies and strategies, even short-term bridging strategies, that could protect patients during this early vulnerable period following a heart attack." said Solomon.

This research was supported by a grant from Novartis Pharmaceuticals.

BWH is a 735-bed nonprofit teaching affiliate of Harvard Medical School and a founding member of Partners HealthCare System, an integrated health care delivery network. Internationally recognized as a leading academic health care institution, BWH is committed to excellence in patient care, medical research and the training and education of health care professionals. The hospital's preeminence in all aspects of clinical care is coupled with its strength in medical research. A leading recipient of research grants from the National Institutes of Health, BWH conducts internationally acclaimed clinical, basic and epidemiological studies. For more information about BWH, please visit: www.brighamandwomens.org

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