Restrictive Cardiomyopathy, Congenital Heart Disease Patients Have Higher Risks of Death Awaiting Transplantation

Patients with restrictive cardiomyopathy, congenital heart disease, and prior heart transplantation have a higher risk of death awaiting orthotopic heart transplantation (OHT) compared with patients who had dilated cardiomyopathy, ischemic cardiomyopathy, hypertrophic cardiomyopathy, and valvular heart disease, according to study findings published in JACC: Heart Failure.

Researchers selected adults in the Scientific Registry of Transplant Recipients database who were awaiting OHT from 2004 to 2014 and assessed outcomes based on heart disease type. The primary end point was time to all-cause mortality, censored at last patient follow-up and time of transplantation. Survival by type of cardiomyopathy was evaluated using multivariable Cox proportional hazard models.

In total, there were 30 747 adult patients (25% women) with heart failure: 14 447 patients with dilated cardiomyopathy, 823 patients with restrictive cardiomyopathy, 11 799 patients with ischemic cardiomyopathy, 602 patients with hypertrophic cardiomyopathy, 964 patients with congenital heart disease, 584 patients with valvular disease, and 1528 patients with “other” conditions, including 1216 patients for re-transplantation.

Patients with dilated cardiomyopathy represented the largest subgroup (47% of the cohort; mean age: 49 years). They also had one of the highest usages of inotropes, implantable cardioverter-defibrillators (ICD), permanent mechanical circulatory support (eg, left ventricular assist device, right ventricular assist device, and total artificial heart), and few patients who required mechanical ventilation or dialysis.

Meanwhile, restrictive cardiomyopathy patients (3% of the total cohort) had the highest percent of prior malignancy. This group had slightly more patients compared to other subgroups requiring dialysis, but with fewer patients receiving temporary or permanent circulatory support, and mechanical ventilation. 

Ischemic cardiomyopathy patients made up 38% of the total cohort with a larger proportion of older patients (mean age: 58 years) and more men compared to the other subgroups. These patients had the highest frequency of diabetes, peripheral vascular disease, and permanent mechanical circulatory support.

Hypertrophic cardiomyopathy patients made up 2% of the total cohort (mean age: 46 years) and were mostly white. These patients had the highest usage of ICDs and there were relatively few patients on mechanical circulatory support, inotropes, dialysis, or mechanical ventilation.

The smallest subgroup was valvular cardiomyopathy (mean age: 54 years) with the highest use of antiarrhythmic medications and inotropes, but relatively low use of mechanical circulatory support, dialysis, or mechanical ventilation.

Patients with congenital heart disease were the youngest of the total cohort (mean age: 36 years), mostly white, and had the lowest body mass index levels.

The median follow-up period was 3.7 months, during which 4943 patients died. Researchers adjusted for possible confounding variables including age, renal function, inotropes, mechanical ventilation, and mechanical circulatory support. The adjusted hazard ratios (aHR) for risk of death by diagnoses relative to dilated cardiomyopathy were: restrictive cardiomyopathy aHR: 1.70 (95% confidence interval [CI]: 1.43-2.02), ischemic cardiomyopathy aHR: 1.10 (95% CI: 1.03-1.18), hypertrophic cardiomyopathy aHR: 1.23 (95% CI: 0.98-1.54), valvular disease aHR: 1.30 (95% CI: 1.07-1.57), congenital heart disease aHR: 1.37 (95% CI: 1.17-1.61), and “other” aHR: 1.51 (95% CI: 1.34-1.69).

Heart transplantation rates were highest among patients with restrictive cardiomyopathy and hypertrophic cardiomyopathy and lowest among patients with congenital heart disease and “other” types of heart disease. In addition, there was an interaction between sex and heart disease type with women compared to men. Women had a higher risk of death with ischemic cardiomyopathy (P<.01) and “other” disease (P=.03) and lower risk of death with restrictive cardiomyopathy (P=.048).

“Our research is the first to document differences in adult outcome based on type of cardiomyopathy while awaiting heart transplantation,” the authors noted. “The results for adults with restrictive cardiomyopathy are similar to pediatrics. Poor survival among patients with heart diseases like restrictive cardiomyopathy, congenital heart disease, and “other” may be due to differences in the underlying disease or our ability to rescue patients with inotropes and permanent mechanical circulatory support while they wait for transplantation.”

In light of the fact that the current heart allocation system does not account for higher risks of death in patients with restrictive cardiomyopathy, congenital disease, and prior heart transplantation vs patients with dialated cardiomyopathy, ischemic cardiomyopathy, hypertrophic cardiomyopathy, or valvular heart disease, researchers believe changes should be implemented to reflect these differences.

“A revised heart allocation scheme has been proposed that will recognize these subgroups and should account for the disadvantaged,” they concluded.

Reference

Hsich EM, Rogers JG, McNamara DM, et al. Does survival on the heart transplant waiting list depend on the underlying heart disease? JACC Heart Fail. 2016. doi:10.1016/j.jchf.2016.03.010.