In left ventricular assist device (LVAD) implantation, patients with an a priori bridge-to-recovery strategy typically have higher rates of cardiac recovery, according to research published in the Journal of the American College of Cardiology.
Researchers from the University of Utah School of Medicine and other medical institutions assessed more than 15,000 LVAD recipients from INTERMACS (Interagency Registry for Mechanically Assisted Circulatory Support) to determine the incidence of cardiac recovery as well as patient characteristics by LVAD implantation strategy. Patients in the Utah Cardiac Recovery program were used as a validation cohort.
Because LVAD implantation is usually a bridge therapy to transplantation or intended for lifetime support, the investigators noted that little research has been devoted to understanding the heart’s potential for recovery. Reverse modeling and improved myocardial function are possible, which can lead to LVAD removal or even avoiding transplantation altogether.
Cardiac recovery was independently predicted by 6 factors: age (<50 years), nonischemic cardiomyopathy, time from cardiac diagnosis being <2 years, lack of an implantable cardioverter defibrillator (ICD), serum creatinine level ≤1.2 mg/dL, and LV end-diastolic dimension <6.5 cm.
From these factors, the researchers developed a prognostic score—the INTERMACS Cardiac Recovery Score (I-CARS)—by assigning a number of points to each variable proportional to its regression coefficient. The score ranged from 0 to 9, and each patient’s score was derived by calculating a sum of points that corresponded to his or her risk factors. I-CARS had an area under the receiver-operating characteristics curve of 0.84 (95% confidence interval [CI], 0.81-0.87) and was able to stratify patients based on the probability of cardiac response in the low, intermediate, and high probability groups (10%, 13%, and 29%, respectively), but with a lower discrimination power (area under the curve: 0.58; 95% CI, 0.56-0.60).
A total of 192 patients (1.3%) in the INTERMACS population experienced cardiac recovery that led to LVAD explantation (n=172) or device deactivation (n=20) after a median of 323.3 days. Reasons for nonrecovery in other patients included device malfunction, device thrombosis, and device infection.
Meanwhile, within the validation cohort, the prognostic value of I-CARS was evaluated in 2 patient populations: those who had an improvement in LV ejection fraction (LVEF) ≥50% relative to baseline and a final LVEF ≥40% (labeled as “cardiac responders”), and within this group, those who had LVAD explantations due to “cardiac recovery.” Patients who had high probability of cardiac response and recovery experienced significant improvement in myocardial function (cardiac response=50%; cardiac recovery=39%). I-CARS was able to discriminate between response (area under the curve: 0.72; 95% CI, 0.59-0.85) and recovery (area under the curve: 0.94; 95% CI, 0.91-0.98).
While cardiac recovery did not occur often early after LVAD implantation, it did increase over time, with 80% occurring 2 years later. In addition, the researchers compared patients who had an a priori bridge-to-recovery strategy vs those who did not. Patients who had successful explantations tended to be younger, were more likely to be women of Hispanic ethnicity, had lower body mass indices, had shorter durations of heart failure, were less likely to have ICDs or previous cardiac surgeries, and were more symptomatic.
“LVAD-induced cardiac recovery is a real and under-recognized phenomenon,” the authors concluded. “Further validation of this bridge-to-pump removal strategy has significant patient and fiscal impacts by potentially reducing resource utilization and morbidity associated with long-term mechanical support and transplantation in patients likely to achieve cardiac recovery.”
- Lack of data on patient selection, monitoring and weaning protocols, and explantation criteria due to the retrospective study design.
- The researchers also dichotomized variables, which may have limited the provision of more refined data.
Disclosures: Dr Drakos has received research support from Abiomed, Inc. and has served as a consultant for HeartWare. Dr Stehlik has received research support from St. Jude Medical and speakers’ bureau fees from HeartWare.