Risk Stratification of High-Risk LVAD Recipients | Journal Scan
What is the validity of the Heartmate Risk Score (HMRS) in a “real-world” population of Heartmate II (HMII) recipients?
The HMRS was calculated in a retrospective cohort of 269 patients who underwent HMII implantation at Barnes Jewish Hospital (BJH) between June 2005 and June 2013. HMRS was calculated as low (<1.58), mid (1.58-2.48), and high (>2.48), as described in the original publication. Baseline characteristics were compared between the BJH cohort and an HMRS derivation cohort. Ninety-day and 2-year mortality were compared by HMRS category. HMRS was also calculated in patients classified as INTERMACS class 1. Receiver operating curve (ROC) was generated along with area under the curve (AUC) to determine the ability of HMRS to predict 90-day mortality. Two-year survival was compared between HMRS categories using Kaplan-Meier curves.
The cohort was predominantly male (81%) and Caucasian (74%). Aside from a greater number of bridge-to-transplant patients in the BJH cohort, baseline characteristics were similar between the BJH cohort and the HMRS derivation cohort. HMRS was found to be a strong predictor of 90-day mortality with an AUC of 0.70 (95% confidence interval, 0.6-0.79). Mortality was incrementally associated with HMRS, and patients with high HMRS had a mortality almost 4 times that of those with low HMRS (32.7% vs. 8.3%, respectively). Two-year survival was statistically different between the HMRS categories, and among destination therapy patients, those in the high HMRS category had a 2-year mortality of 84.6% compared to 36.4% in the low HMRS group. High HMRS was associated with a high rate of gastrointestinal bleeding events and number of hospital days during the first year post-implant. Finally, HMRS discriminated both 90-day and 2-year mortality risk among INTERMACS class 1 patients.
The authors concluded that HMRS is a valid tool to stratify risk of short- and long-term mortality and morbidity after HMII implantation in an unselected population.
The use of risk scores may greatly enhance clinicians’ ability to appropriately select patients for advanced heart failure therapies; however, a major criticism of risk scores is the lack of generalizability. This study validated the HMRS as a predictor of short- and long-term mortality in a ‘real-world’ population, even among INTERMACS class 1, and demonstrated promise in its ability to predict clinical events. Prospective studies are required for the latter. The generalizability to lower volume centers is unclear.
Keywords: Heart Failure, Morbidity, Mortality, Heart-Assist Devices, Area Under Curve, Risk, Risk Assessment, Survival, Retrospective Studies, Cohort Studies
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