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Published on: August 16, 2021
Creation and Validation of a Novel Sex-Specific Mortality Risk Score in LVAD Recipients
Aditi Nayak1, Yingtian Hu2, Yi-An Ko1,2
1Division of Cardiology Department of Medicine Emory Clinical Cardiovascular Research InstituteEmory University School of Medicine Atlanta GA.
Insights
Women have worse survival after left ventricular assist device (LVAD) implantation. A new sex-specific IMACS Risk Score improves early mortality prediction in LVAD patients, outperforming existing scores.
Area of Science:
- Cardiovascular Surgery
- Medical Devices
- Prognostic Modeling
Background:
- Women exhibit poorer 3-month survival rates post-left ventricular assist device (LVAD) implantation compared to men.
- Existing prognostic scores, such as the Heartmate II Risk Score, do not adequately address the heightened residual risk observed in female LVAD recipients.
- The International Society for Heart and Lung Transplantation Mechanically Assisted Circulatory Support (IMACS) registry provides a robust dataset for developing sex-specific predictive models.
Purpose of the Study:
- To develop and validate a novel sex-specific risk score for predicting early mortality in adult patients receiving a continuous-flow left ventricular assist device (LVAD).
- To assess the performance of the new IMACS Risk Score against the established Heartmate II Risk Score in diverse patient cohorts.
- To identify key preoperative predictors and sex-specific interactions influencing 3-month mortality in LVAD recipients.
Main Methods:
- Utilized the IMACS registry, randomly dividing 15,187 adult continuous-flow LVAD recipients into a derivation cohort (n=9113) and a validation cohort (n=6074).
- Developed the IMACS Risk Score using preoperative candidate predictors selected via Akaike information criterion and significant sex × variable interactions in the derivation cohort.
- Evaluated the score's predictive accuracy and calibration using receiver operating characteristic (ROC) analysis and compared it with the Heartmate II Risk Score.
Main Results:
- The IMACS Risk Score incorporated age, cardiogenic shock, BMI, BUN, bilirubin, hemoglobin, albumin, platelets, LV end-diastolic diameter, tricuspid regurgitation, dialysis, and pre-implantation infection.
- Significant sex interactions were found for ischemic heart failure and platelet count, highlighting differential risk factors.
- The IMACS Risk Score demonstrated superior predictive performance (ROC AUC: men 0.71-0.69, women 0.73-0.71) compared to the Heartmate II Risk Score, with excellent calibration in both sexes.
Conclusions:
- A sex-specific risk score, the IMACS Risk Score, significantly enhances the prediction of 3-month mortality in left ventricular assist device recipients.
- The model's performance significantly degraded when sex-specific interaction terms were removed, underscoring the importance of sex in risk stratification.
- The IMACS Risk Score offers improved clinical utility for personalized risk assessment and management of LVAD patients.
Abstract:
Background Prior studies have shown that women have worse 3-month survival after receiving a left ventricular assist device compared with men. Currently used prognostic scores, including the Heartmate II Risk Score, do not account for the increased residual risk in women. We used the IMACS (International Society for Heart and Lung Transplantation Mechanically Assisted Circulatory Support) registry to create and validate a sex-specific risk score for early mortality in left ventricular assist device recipients. Methods and Results Adult patients with a continuous-flow LVAD from the IMACS registry were randomly divided into a derivation cohort (DC; n=9113; 21% female) and a validation cohort (VC; n=6074; 21% female). The IMACS Risk Score was developed in the DC to predict 3-month mortality, from preoperative candidate predictors selected using the Akaike information criterion, or significant sex × variable interaction. In the DC, age, cardiogenic shock at implantation, body mass index, blood urea nitrogen, bilirubin, hemoglobin, albumin, platelet count, left ventricular end-diastolic diameter, tricuspid regurgitation, dialysis, and major infection before implantation were retained as significant predictors of 3-month mortality. There was significant ischemic heart failure × sex and platelet count × sex interaction. For each quartile increase in IMACS risk score, men (odds ratio [OR], 1.86; 95% CI, 1.74-2.00; P<0.0001), and women (OR, 1.93; 95% CI, 1.47-2.59; P<0.0001) had higher odds of 3-month mortality. The IMACS risk score represented a significant improvement over Heartmate II Risk Score (IMACS risk score area under the receiver operating characteristic curve: men: DC, 0.71; 95% CI, 0.69-0.73; VC, 0.69; 95% CI, 0.66-0.72; women: DC, 0.73; 95% CI, 0.70-0.77; VC, 0.71 [95% CI, 0.66-0.76; P<0.01 for improvement in receiver operating characteristic) and provided excellent risk calibration in both sexes. Removal of sex-specific interaction terms resulted in significant loss of model fit. Conclusions A sex-specific risk score provides excellent risk prediction in LVAD recipients.
