Patient selection for mechanical bridging to transplantation

Patients with advanced heart failure often cannot undergo cardiac transplantation soon enough to prevent fatal hemodynamic deterioration or sudden death. The approach to these patients includes tailoring of medical therapy with vasodilators and diuretics, which allows stabilization of 60% to 80% of potential candidates. Current criteria for mechanical support before transplantation currently focus on the identification of hospitalized patients with at least 30% chance of death before transplantation. The much larger question relates to the potential use of mechanical support to bridge ambulatory patients, who represent 90% to 95% of the transplant waiting list, with waiting times frequently exceeding 2 years.

From 1988 to 1993, 265 potential candidates were discharged after evaluation for transplantation with New York Heart Association class IV status and left ventricular ejection fraction of 0.25 or less. Patients were analyzed for clinical hemodynamic and echocardiographic profiles that would identify ambulatory patients unlikely to survive without urgent transplantation.

After tailored medical therapy, presenting hemodynamic parameters are not useful for predicting 2-year survival without urgent transplantation, which was 45% at 2 years. Left ventricular diastolic dimension of 80 mm or greater was associated with only 29% two-year survival without urgent transplantation. Serum sodium level less than 132 mEq/L predicted 35% two-year survival without urgent transplantation. Peak oxygen consumption less than 10 mL.kg-1.min-1 identified poor outcome but was often not measured in patients with resting symptoms.

Although definition of indications for urgent bridging requires complex clinical assessment based on immediate risk, it should be possible to identify a larger ambulatory population for whom improved devices will offer extended survival without transplantation.