Circ: Hypertrophic cardiomyopathy linked with long-term survival after transplant
Heart transplant patients with hypertrophic cardiomyopathy may have similar short-term survival compared to those with ischemic cardiomyopathy, dilated cardiomyopathy and restrictive cardiomyopathy, but they have greater long-term survival rates, according to a study published in this month’s Circulation: Heart Failure.

"Hypertrophic cardiomyopathy is the most common genetic cardiovascular disease and is characterized by a diverse phenotypic expression and heterogeneous clinic course, including a major cause of heart failure symptoms and death in patients of all ages," the authors wrote. "[T]he clinical profile and prognosis of hypertrophic cardiomyopathy patients who undergo cardiac transplantation remains uncertain."

Martin S. Maron, MD, of Tufts Medical Center in Boston, and colleagues evaluated clinical outcomes of 26,706 transplant patients over a 15-year period. The researchers utilized the Organ Procurement and Transplantation Network registry, operated by the United Network of Organ Sharing, to identify the patients enrolled in the study and to assess the occurrence and prognosis of hypertrophic cardiomyopathy patients.

The researchers split patients into two groups: those with hypertrophic cardiomyopathy (303 patients) and those with non-hypertrophic cardiomyopathy (26,403), who were diagnosed with either of the following: ischemic cardiomyopathy (14,308), dilated cardiomyopathy (11,760) or restrictive cardiomyopathy (335).

Of the patients enrolled in the study, 81 percent were white, 79 percent were male and all had an average age of 52. According to the researchers, patients with hypertrophic cardiomyopathy were younger, were more likely to be women and had an average age of 43. All patients underwent transplant surgery between January 1990 and December 2004. All heart transplant patients were first-time, single-organ, heart-only transplants. Repeat transplant patients were excluded from the study and mean patient follow-up was 76 months.

Researchers found that 84 patients with hypertrophic cardiomyopathy died--70 were due to non-cardiac causes and 14 were cardiac-death related. More non-hypertrophic cardiomyopathy patients died from cardiac reasons compared to those with the hypertrophic condition, 17 versus 10 percent, respectively.

The researchers found that hypertrophic cardiomyopathy patients had similar one-year survival rates when compared to those with other types of heart disease, 85 versus 82 percent, respectively.

When looking at long-term results, the researchers found that after a five-year follow-up, these survival rates decreased and were 75 percent for hypertrophic cardiomyopathy patients and 70 percent for other surviving patients.

After 10 years, survival rates dropped significantly but were higher for hypertrophic cardiomyopathy patients compared to others, 61 versus 49 percent, respectively.

"Patients with this disease who are undergoing transplant can expect reasonable long-term survival rates," said Maron and colleagues. "That's a crucial clinical message for this small but important subgroup of patients.

"[A]fter adjusting for time varying effects on all-cause mortality rates after transplant, HCM patients demonstrated higher mortality only after the initial first several months following transplantation but overall lower long-term mortality."

The researchers said that limitations may stem from missing echocardiographic information on patients, which could have led to hypertrophic cardiomyopathy patients who may have been improperly categorized.

"These data suggest that patients with hypertrophic cardiomyopathy who are candidates for cardiac transplantation should be reassured of reasonable long-term survival rates," the authors concluded.