SAN FRANCISCO — Patients with transplanted hearts face a higher risk of sudden cardiac death if they have left ventricular ejection fractions below 40%, a retrospective study of 208 patients found.
The risk for sudden cardiac death is compounded if the patient also has cardiac allograft vasculopathy of any severity, Dr. Michelle Montpetit and her associates reported at the annual meeting of the International Society for Heart and Lung Transplantation.
“It would be reasonable to consider implantation of defibrillators in heart transplant patients with an ejection fraction of less than 40% and cardiac allograft vasculopathy of any severity,” said Dr. Montpetit of Loyola University, Maywood, Ill.
Identifying these patients early is important, she said, because 73% of patients in the study who died of sudden cardiac death did so within the first 5 years after heart transplantation.
Implantable cardioverter defibrillators (ICDs) are recommended for nontransplant patients with heart failure to prevent sudden cardiac death. Previous studies have shown that defibrillators improve survival in nontransplant patients with a history of MI and an ejection fraction below 30%, and in nontransplant patients with cardiomyopathy and an ejection fraction below 35%.
Several previous small studies suggest that 6%–37% of patients after heart transplantation die of sudden cardiac death. The only previous study of ICD use in patients after heart transplant found that 3 of 10 patients were cardioverted appropriately during 13 months of follow-up. They had received ICDs for indications including low ejection fraction and coronary disease, syncope, or symptomatic ventricular tachycardia.
The current study examined data on 208 of 617 patients who underwent heart transplantation at Loyola University Medical Center from 1984 to 2005. The 208 died during those 2 decades, 27% of them from sudden cardiac death, which was defined as a witnessed arrhythmic death or a sudden death at home or in the hospital with no known cause.
Patients with sudden cardiac death were more likely to have undergone heart transplantation for ischemic cardiomyopathy (64%), compared with 46% of patients who died of other causes. Other clinical and demographic characteristics were similar between groups.
The only single factor associated with sudden cardiac death in multivariate analysis was left ventricular ejection fraction. Among the entire cohort, 40% of patients with ejection fractions below 40% died of sudden cardiac death, compared with 22% of patients with greater ejection fractions. Of the 56 patients with sudden cardiac death, 23 (41%) had ejection fractions below 40%.
Cardiac allograft vasculopathy by itself was not associated with risk of sudden cardiac death, but when combined with a low ejection fraction, it increased the risk of sudden cardiac death to 52%, Dr. Montpetit said.
Among a subset of patients who underwent coronary angiography near the time of death, 4 had mild cardiac allograft vasculopathy (defined as any lesion less than 50% of a major vessel) and 13 had severe vasculopathy (lesions greater than 50%). The severity of vasculopathy did not appear to affect the risk of sudden cardiac death.
The findings were limited by the retrospective nature of the study, its small size, and the lack of autopsy data to confirm the cause of death, Dr. Montpetit said. Not all patients had coronary angiography or ejection fraction measurements near the time of death. The records may have been skewed by the fact that “we tend to collect more data on patients with acute rejection,” she said.
A posttransplant history of at least one episode of severe rejection was significantly more common in patients who later died of sudden cardiac death (64%) than in patients who died of other causes (46%).