Abstract 18299: Device Selection: Does Ventricular Size Matter in LVAD Recipients?

Abstract

Introduction: Axial and centrifugal-flow left ventricular assist devices (LVAD) have varied response to changes in loading conditions. Whether ventricular size modulates the response to LVAD therapy between the axial flow Heartmate II (HMII) and centrifugal flow Heartware (HVAD) is unknown. Hypothesis: Adverse event and survival rates between devices are affected by recipient pre-op left ventricular end-diastolic diameter (LVEDD). Methods: Data on 1,149 continuous-flow LVAD recipients from May 2004 to May 2015 was pooled from the Mechanical Circulatory Support Research Network (MCSRN). The effect of pre-op LVEDD on the instantaneous hazard of death and adverse events was evaluated between HMII (n=864) and HVAD (n=283). Results: The average LVEDD was 7.0cm and did not differ between the device recipients. Patients with a smaller LVEDD (≤ 6.3cm) were more likely female 39% v. 24% (p < 0.0001) and to have an ischemic cardiomyopathy (30% v. 24%, p = 0.045). For every 1cm increase in pre-op LVEDD, the adjusted hazard ratio (HR) for mortality increased with HVAD (HR 1.31, 95% CI 0.94-1.82, p = 0.005) and decreased with HMII (HR 0.78, 95% CI 0.67-0.92, p = 0.005), Figure 1a. Other predictors of mortality included age (HR 1.31, 95% CI 1.12 - 1.53 per 10y, p < 0.001) and bilirubin (HR 1.15, 95% CI 0.94-1.42 per mg/dL, p = 0.027). LVEDD by device type interaction was not a significant predictor of gastrointestinal bleeding or pump thrombosis. The risk of stroke increased with LVEDD for HVAD and decreased for HMII, but this did not reach statistical significance, Figure 1b. Ischemic etiology of heart failure (HR 1.7 95% CI 1.14 - 2.55, p = 0.01) and HVAD device use (HR 1.47 95% CI 1.00 - 2.17, p = 0.03) were significant predictors of stroke. Conclusions: Our data suggest important differences exist in patient outcomes between HMII and HVAD based on pre-op ventricular size. Studies are needed to determine if these differences in outcome are due to device or flow-specific differences in patient support.