The risk of sudden death or cardiac arrest is highest in the first 30 days after a heart attack among patients with heart failure, write researcher Scott Solomon, MD, and colleagues.
Sudden death is the abrupt loss of heart function. The heart stops beating, usually after an arrhythmia -- an irregular or rapid heartbeat.
Earlier use of sudden-death prevention strategies might be needed for some patients, they write.
Study of Heart Attack Survivors
Solomon's group studied about 14,600 heart attack survivors. All had heart failure.
Heart failure is a major risk factor for death, including sudden death after heart attacks. After a heart attack, scar tissue can interfere with the pumping action of the heart muscles.
The study participants were followed for about two years, on average; 903 died suddenly and 164 were resuscitated after cardiac arrest. That's 1,067 people, or 7% of the entire group.
"Many had recently been discharged from the hospital," say the researchers. In fact, 83% of sudden deaths happened in the first 30 days after leaving the hospital.
Of those who were resuscitated, two-thirds (108 patients) were alive six months later; 57% (93 people) were alive when the study ended.
On average, sudden death and resuscitation occurred 180 days after patients' initial heart attack. The risk was highest during the first 30 days, tapering off over the next two years, say the researchers.
During the first month after a heart attack, 126 patients died suddenly and 72 were resuscitated after cardiac arrest. That's 19% of all patients who experienced such events during the study.
In that crucial first month, the highest risk was seen in people with significant heart failure.
However, those whose hearts could pump more blood were not out of the woods. Even among those with less severe heart failure the rate of sudden death or cardiac arrest was more than six times as high in the first month as after one year, say the researchers.
With time, the difference in the degree of heart failure became less important, the researchers say.
It's not known if early therapy with a heart device called an implantable cardioverter defibrillator (ICD) would help, say the researchers. ICDs monitor the heart's rate and rhythm, shocking it back to a normal rhythm when needed.
However, the researchers say that in view of "recent data demonstrating the benefits of ICD therapy in high-risk patients, our data suggest the need to consider implementing strategies to prevent sudden death in selected patients before the time recommended by current guidelines."
The study was funded by Novartis Pharmaceuticals. Novartis is a WebMD sponsor.