Nadav Nahumi

Prevalence, Significance, and Management of Aortic Insufficiency in Continuous Flow Left Ventricular Assist Device Recipients

Background— Aortic insufficiency (AI) is increasingly recognized as a complication of continuous flow left ventricular assist device support; however, its long-term prevalence, clinical significance, and efficacy of potential interventions are not well known. Methods and Results— We studied the prevalence and management of AI in 232 patients with continuous flow left ventricular assist device at our institution. Patients with aortic valve (AV) surgery before left ventricular assist device implantation were excluded from analysis. To examine the prevalence of de novo AI, patients without preoperative AI were divided into a retrospective and a prospective cohort based on whether a dedicated speed optimization study had been performed at the time of discharge. Forty-three patients underwent AV repair at the time of implant, and 3 subsequently developed greater than mild AI. In patients without surgical AV manipulation and no AI at the time of implant, Kaplan–Meier analysis revealed that freedom from greater than mild de novo AI at 1 year was 77.6±4.2%, and that at least moderate AI is expected to develop in 37.6±13.3% after 3 years. Nonopening of the AV was strongly associated with de novo AI development in patients without prospective discharge speed optimization. Seven of 21 patients with at least moderate AI developed symptomatic heart failure requiring surgical intervention. Conclusions— AI is common in patients with continuous flow left ventricular assist devices and may lead to clinical decompensation requiring surgical correction. The prevalence of AI is substantially less in patients whose AV opens, and optimized loading conditions may reduce AI prevalence in those patients in whom AV opening cannot be achieved.

Pre-operative mortality risk assessment in patients with continuous-flow left ventricular assist devices: Application of the HeartMate II risk score

BACKGROUND Survival with left ventricular assist device (LVAD) therapy is dependent on appropriate patient selection. The HeartMate II risk score (HMRS) was recently derived and validated to predict 90-day mortality in clinical trial patients with continuous-flow LVADs. The aim of this study was to test HMRS validity in predicting survival at our institution. METHODS We performed a retrospective analysis of patients implanted with HeartMate II (HMII; Thoratec, Pleasanton, CA) LVADs from March 31, 2004 to September 20, 2012 at the Columbia University Medical Center (CUMC). Patients were stratified according to HMRS profiles (HMRS Low < 1.58, 1.58 ≤ HMRS Medium ≤ 2.48, HMRS High > 2.48) calculated using age, albumin, creatinine, international normalized ratio (INR) and center volume. Outcome was defined as survival at 90 days after device implantation. RESULTS HeartMate II LVADs were implanted in 205 patients. Pre-operative data from 201 patients were categorized into HMRS Low (n = 101; 1.04 [0.64 to 1.31]), HMRS Medium (n = 73; 1.98 [1.78 to 2.25]) and HMRS High (n = 27, 3.07 [2.70 to 3.43]) (p < 0.0001). Kaplan-Meier survival estimates at 90 days (HMRS Low 91.0 ± 2.9%, HMRS Medium 91.7 ± 3.2%, HMRS High 88.7 ± 6.1%) and at 1 year (HMRS Low 85.5 ± 3.8%, HMRS Medium 79.3 ± 5.5%, HMRS High 82.4 ± 8.4%) after LVAD implantation were not statistically different (p = 0.43). Prediction of 90-day mortality by receiver operating characteristic was poor (AUC = 0.56). CONCLUSION HMRS stratification poorly discriminates 90-day mortality after HMII LVAD implantation at our institution. Its generalizability as a universal prognostic score may be limited.

Slope Calculation for the LVAD Ramp Test

We would like to add a letter to our paper previously published by Uriel et al. [(1)][1]. We are honored to have been contacted by many centers nationally and internationally about our ramp test. However, it has come to our attention that some centers performing the test are unfortunately having

Adrenergic Activation, Fuel Substrate Availability, and Insulin Resistance in Patients With Congestive Heart Failure

OBJECTIVES This study sought to investigate plasma levels of glucose and free fatty acids (FFA) and their relationship with adrenergic activation and insulin resistance (IR) in patients with advanced congestive heart failure (CHF). BACKGROUND Adrenergic activation and IR are hallmarks of advanced heart failure. The resulting changes in fuel substrate availability and their implications for exercise capacity have not been elucidated. METHODS Subjects with CHF underwent maximal exercise testing. Plasma glucose, FFA, insulin, and norepinephrine (NE) levels were measured at rest and at peak exercise. Beta-receptor sensitivity to NE was assessed using the Chronotropic Responsiveness Index (CRI). Homeostasis Model Assessment Index >2.5 defined IR. Left ventricular ejection fraction was estimated by 2-dimensional echocardiography. RESULTS Ninety-six subjects were enrolled. CHF subjects without IR (CHF/No-IR), but not those with IR (CHF/IR), significantly increased glucose and insulin in response to exercise. Only CHF/No-IR subjects increased FFA in response to exercise (0.14 ± 0.27 mmol/l; p = 0.027). NE increased significantly less with exercise, and CRI was lower in CHF/IR subjects compared with CHF/No-IR subjects (1.3 ± 1.4 vs. 2.5 ± 2.1; 6.4 ± 2.6 vs. 8.5 ± 3.4; p = 0.069). CRI correlated with the exercise-induced increase in FFA (r = 0.41; p < 0.005). These results stayed the same after excluding diabetic patients from the CHF/IR group. CONCLUSIONS Circulating FFA levels increased during exercise in CHF subjects without IR, but not in those with IR or DM. Increased FFA availability during exercise may represent a catecholamine-dependent compensatory fuel shift in CHF.