Low Left Ventricular Stroke Work Index is Associated with a Poor Prognosis in LVAD Patients

Abstract

<h3>Purpose</h3> Hemocompatibility-related adverse events (HRAE) are thought to be largely driven by the pump-patient interaction. We hypothesized that patients with left ventricular assist devices (LVADs) with low left ventricular stroke work index (LVSWI), and thus less native contribution to total flow, would have more adverse clinical outcomes. <h3>Methods</h3> Hemodynamic data was prospectively collected from LVAD patients who had undergone a right heart catheterization with ramp study at our institution between April 2014 and July 2018. LVSWI was calculated as 0.0136 * ((cardiac index/heart rate) * 1000) * (mean arterial pressure - pulmonary capillary wedge pressure). We used a previously identified cutoff point of 31.73 for LVSWI to separate patients into low and high LVSWI groups. Univariate and multivariate logistic regression analyses were performed to determine the association between LVSWI and HRAE, heart failure (HF) readmission, and mortality. <h3>Results</h3> A total of 93 patients were included in this analysis - average age 61 +/- 11 years, 34% women, 40% Black, and 38% ischemic cardiomyopathy. Low LVSWI was not significantly associated with HRAE (HR 1.65, 95% CI 0.93-2.91, p = 0.081) in univariate analysis, but was statistically significant (HR 1.81, 95% CI 1.02-3.22, p = 0.042) when adjusted for LVAD type (HeartWare HVAD, Heartmate II, and Heartmate 3). Low LVSWI was significantly associated with HF readmission (HR 3.02, 95% CI 1.46-6.24, p = 0.0029) and mortality (HR 2.97, 95% CI 1.29-6.85, p = 0.011), even when adjusted for LVAD type (HR 3.15, 95% CI 1.52-6.54, p = 0.0021 and HR 3.13, 95% CI 1.36-7.21, p = 0.0074, respectively). <h3>Conclusion</h3> Low LVSWI in LVAD patients is associated with poor prognosis and worse clinical outcomes such as increased HF readmission and mortality.