PHILADELPHIA — Left ventricular dysfunction is a powerful predictor of poor outcome in patients who have received a heart transplant.
During 13 years of follow-up of almost 19,000 patients with transplanted hearts, the cumulative rate of left ventricular dysfunction was 23%, Katherine Lietz, M.D., reported at the annual meeting of the International Society for Heart and Lung Transplantation. Left ventricular dysfunction was defined as ejection fractions of 40% or less.
Among heart transplant patients with a left ventricular ejection fraction of 40% or less, the relative risk of cardiac death was 2.65-fold higher than the risk faced by heart transplant patients without left ventricular dysfunction. The risk of noncardiac death in patients with impaired left ventricular function was almost twice that of control patients, due mostly to renal dysfunction that was secondary to heart failure, said Dr. Lietz, a cardiologist at the University of Minnesota in Minneapolis.
The study used data from the U.S. Scientific Registry of Transplant Recipients for heart transplants done during 1990–2003. This registry includes all heart transplant recipients in the United States during this period, a total of 25,719. Exclusion of patients who were lost to follow-up and those who did not survive for at least 1 year left a study group of 18,854 patients, who were followed until they died, until their transplanted hearts failed, or through the end of May 2004.
Aside from the patients who developed heart failure, left ventricular function stayed fairly constant through follow-up that lasted as long as 13 years. The average left ventricular ejection fraction for the entire group was about 59% after 1 year of follow-up and 57% after 13 years. Development of heart failure occurred at a fairly constant rate, in about 2% of patients per year.
The two most powerful risk factors for the development of left ventricular dysfunction were coronary vasculopathy and renal dysfunction, both of which boosted the risk more than twofold.
Other significant risk factors were African American race, which raised the risk by 89%; need for retransplantation, which raised risk by 67%; and acute rejection, which increased the risk by 65%.
The prevalence of vasculopathy was 34% in patients with an ejection fraction of more than 40%. Among those with lower ejection fractions, the prevalence of vasculopathy was much higher, 57%.
The increased risk of death associated with left ventricular dysfunction was proportional to the severity of the dysfunction. Patients with an ejection fraction of 45%–55% had a 25% increased risk of death, compared with patients with ejection fractions of more than 65%. The mortality risk was 57% higher in patients with an ejection fraction of 35%–45%, and was 2.6-fold higher in those with an ejection fraction of less than 35%.
Morbidity and mortality increased dramatically as ejection fraction fell to 35% and less. Among patients with an ejection fraction of 40% or less, the mortality rate was 24%, and an additional 2% of patients needed a repeat transplantation. But among those with ejection fractions of 35% or less, the cumulative mortality was 46%, and 5% of these patients needed repeat transplantation.