Aaronson, Keith D.

Introduction: Age ≥ 70 is used to exclude patients from cardiac transplantation. Elderly patients may be offered left ventricular assist device (LVAD) therapy as an alternative. It remains poorly defined how they respond to LVAD support. Hypothesis: Elderly patients have LVAD outcomes that are non-inferior to younger patients. Methods: Data on 1,149 continuous-flow LVAD recipients from May 2004 to May 2015 was pooled from the Mechanical Circulatory Support Research Network (MCSRN). Groups were assigned based on Age ≥ 70 (n = 163) and < 70 (n = 986). Results: Patients age ≥ 70 were more likely to be male (91%), have an ischemic cardiomyopathy (71%), atrial fibrillation (41%), hypertension (66%), diabetes (38%) and prior sternotomy (45%). Older patients also had a lower BMI and higher creatinine, 26.7 ± 0.4 v. 29.9 ± 0.5 and 1.46 ± 0.04 v. 1.35 ± 0.02, p < 0.05. The hazard ratio for mortality was highest in elderly patients in the early post-operative period and stabilized over time with no long-term differences in survival, p = 0.18, Figure 1a. Elderly patients had equivalent rates of device thrombosis and stroke, p = 0.47 and 0.44, Figures 1b-c. Survival free of gastrointestinal bleeding (GIB) at 1-year was 58% in elderly patients compared to 69% in younger patients, Figure 1d, p < 0.01. Multivariate cox regression revealed that age ≥ 70 was not a significant predictor of mortality (HR 0.93, 95% CI 0.69 - 1.25, p = 0.62), but pre-operative creatinine (HR 1.54, 95% CI 1.28 - 1.86, p < 0.01) and bilirubin (HR 1.2, 95% CI 1.03 - 1.4, p = 0.02) were. When age was considered a continuous variable, the HR was 1.2 (95% CI 1.07 - 1.3 per 10y, p < 0.01). Conclusions: Elderly patients, age ≥ 70, have equivalent long-term survival after LVAD implantation with similar rates of device thrombosis and stroke. Rates of GIB were higher in the elderly and this finding warrants caution when choosing anti-coagulation protocols in the elderly. Overall age ≥ 70 does not portend a poorer survival after LVAD implant.

Introduction: Various risk models have been used to predict mortality after implantation of continuous-flow ventricular assist devices (CF-VADs). Discriminatory power and predictive accuracy vary, and there is a need to develop and validate a contemporary risk score in a large multicenter patient cohort. Hypothesis: We sought to develop an early mortality risk score utilizing a large voluntary research registry of patients implanted with CF-VADs, with the focus on increased discriminatory power. Methods: From May 2004 to May 2015, 1150 patients in the Mechanical Circulatory Support Research Network (MCSRN) registry were randomly divided into equal-sized derivation and validation samples (n=575, each group). Candidate predictors from the derivation sample were subjected to backward stepwise logistic regression until the model with lowest Akaike information criterion value was identified for predicting 90-day mortality. A risk score was developed based on the variables and their respective regression coefficients in the final model. Discriminatory power of the risk score was evaluated using receiver operating characteristic analysis, and calibration was assessed using Hosmer-Lemeshow goodness of fit test. Results: Overall 90-day mortality was 9.4% (n=99). The final logistic regression model consisted of 9 predictors: Age at implant, preoperative mechanical ventilation, serum total bilirubin, hemoglobin, tricuspid valve regurgitation severity, left ventricular end-diastolic diameter, cardiac index, pulmonary capillary wedge pressure, and destination therapy (DT) as an indication for pump placement. The area under the curve was 0.86 in the derivation sample (95% CI, 0.75-0.97) and 0.75 in the validation sample (95% CI, 0.63-0.86). Hosmer-Lemeshow goodness of fit test yielded insignificant values in both samples (p=0.75, p=0.58) consistent with good calibration. Conclusions: The proposed 90-day mortality MCSRN risk score provides highest-to-date discriminatory power when compared to already published models. The risk score is applicable to a contemporary large cohort of patients implanted with CF-VADs for either indication (bridge or DT).

Introduction: Recent reports have documented an abrupt increase in 3-month confirmed HeartMate II left ventricular assist device (LVAD) thrombosis beginning in 2011 without a plateau observed to date. Because very little data exist from multi-institutional efforts, we report our experience. Methods: From January 2004 to December 2013, 516 pt underwent HeartMate II LVAD implant at three institutions (University of Michigan (n=254), Mayo Clinic Rochester (n=205), and Vanderbilt Heart and Vascular Institute (n=57)). Median age at implant was 60 yr (range, 18-82) and 428 (83%) were male. Confirmed pump thrombosis at 3 months was defined as thrombus found in the blood-contacting surfaces of the pump at the time of urgent transplant, device exchange or autopsy. Pt without at least 3 months of follow-up were excluded. Results: Confirmed pump thrombosis occurred in 9 pt within 3 months post implant. The incidence was greatest in the year 2012 (5.3%). Following this peak, the incidence of 3-month confirmed pump thrombosis decreased significantly to 2.9% (Figure). Significant differences in preoperative characteristics between patients with pump thrombosis and without thrombosis included female sex (36% vs. 16%, p=0.01), bridge to transplant (77% vs. 54%, p=0.03), atrial fibrillation (55% vs. 32%, p=0.04), and preop platelet count (231,000 vs. 172,000, p<0.001). Follow-up was available in all for a total of 857 patient years of support. At a median follow-up of 1.2 years (max., 9.8 years), a similar proportion of patients were alive (73% vs. 74%, p=0.9). Conclusions: We report a recent decrease in early, confirmed HeartMate II LVAD thrombosis to historically observed levels, which is disparate to recent reports. While we identified several differences in clinical characteristics between patient groups, the issue of pump thrombosis is complex and multifactorial. Most importantly, our findings demonstrate the need for more granular analyses from collaborative efforts.

Introduction: Axial and centrifugal-flow left ventricular assist devices (LVAD) have varied response to changes in loading conditions. Whether ventricular size modulates the response to LVAD therapy between the axial flow Heartmate II (HMII) and centrifugal flow Heartware (HVAD) is unknown. Hypothesis: Adverse event and survival rates between devices are affected by recipient pre-op left ventricular end-diastolic diameter (LVEDD). Methods: Data on 1,149 continuous-flow LVAD recipients from May 2004 to May 2015 was pooled from the Mechanical Circulatory Support Research Network (MCSRN). The effect of pre-op LVEDD on the instantaneous hazard of death and adverse events was evaluated between HMII (n=864) and HVAD (n=283). Results: The average LVEDD was 7.0cm and did not differ between the device recipients. Patients with a smaller LVEDD (≤ 6.3cm) were more likely female 39% v. 24% (p < 0.0001) and to have an ischemic cardiomyopathy (30% v. 24%, p = 0.045). For every 1cm increase in pre-op LVEDD, the adjusted hazard ratio (HR) for mortality increased with HVAD (HR 1.31, 95% CI 0.94-1.82, p = 0.005) and decreased with HMII (HR 0.78, 95% CI 0.67-0.92, p = 0.005), Figure 1a. Other predictors of mortality included age (HR 1.31, 95% CI 1.12 - 1.53 per 10y, p < 0.001) and bilirubin (HR 1.15, 95% CI 0.94-1.42 per mg/dL, p = 0.027). LVEDD by device type interaction was not a significant predictor of gastrointestinal bleeding or pump thrombosis. The risk of stroke increased with LVEDD for HVAD and decreased for HMII, but this did not reach statistical significance, Figure 1b. Ischemic etiology of heart failure (HR 1.7 95% CI 1.14 - 2.55, p = 0.01) and HVAD device use (HR 1.47 95% CI 1.00 - 2.17, p = 0.03) were significant predictors of stroke. Conclusions: Our data suggest important differences exist in patient outcomes between HMII and HVAD based on pre-op ventricular size. Studies are needed to determine if these differences in outcome are due to device or flow-specific differences in patient support.

Abstract Various risk models with differing discriminatory power and predictive accuracy have been used to predict right ventricular failure (RVF) after left ventricular assist device (LVAD) placement. There remains an unmet need for a contemporary risk score for continuous flow (CF)‐LVADs. We sought to independently validate and compare existing risk models in a large cohort of patients and develop a simple, yet highly predictive risk score for acute, severe RVF. Data from the Mechanical Circulatory Support Research Network (MCSRN) registry, consisting of patients who underwent CF‐LVAD implantation, were randomly divided into equal‐sized derivation and validation samples. RVF scores were calculated for the entire sample, and the need for a right ventricular assist device (RVAD) was the primary endpoint. Candidate predictors from the derivation sample were subjected to backward stepwise logistic regression until the model with lowest Akaike information criterion value was identified. A risk score was developed based on the identified variables and their respective regression coefficients. Between May 2004 and September 2014, 734 patients underwent implantation of CF‐LVADs [HeartMate II LVAD, 76% ( n = 560), HeartWare HVAD, 24% ( n = 174)]. A RVAD was required in 4.5% ( n = 33) of the patients [Derivation cohort, n = 15 (4.3%); Validation cohort, n = 18 (5.2%); P = 0.68)]. 19.5% of the patients ( n = 143) were female, median age at implant was 59 years (IQR, 49.4–65.3), and median INTERMACS profile was 3 (IQR, 2–3). RVAD was required in 4.5% ( n = 33) of the patients. Correlates of acute, severe RVF in the final model included heart rate, albumin, BUN, WBC, cardiac index, and TR severity. Areas under the curves (AUC) for most commonly used risk predictors ranged from 0.61 to 0.78. The AUC for the new model was 0.89 in the derivation and 0.92 in the validation cohort. Proposed risk model provides very high discriminatory power predicting acute severe right ventricular failure and can be reliably applied to patients undergoing placement of contemporary continuous flow left ventricular assist devices.

Highly specialized left ventricular assist device care is not readily available in many areas, potentially limiting access to therapy. This retrospective analysis examines the relationship of outcomes by patient distance from implanting left ventricular assist device center within the Mechanical Circulatory Support Research Network. Zip codes were used to calculate patient distance, with the primary outcome of interest being 3-year survival by distance from the surgical center. Secondary outcomes included 90-day survival and incident event rates for the following: gastrointestinal bleeding, infection, cerebral event, and pump thrombosis. Across the four centers, there were 1184 patients supported for a median of 486 days. Overall survival was 91 ± 0.8% at 90 days and 61 ± 1.9% at 3 years, with worse 3-year survival in those living >90 vs . ≤90 miles from the ventricular assist device implant center (55 ± 3.0% vs . 64 ± 2.5, p = 0.019). Patients living >90 miles from an implant center were older, more likely to be implanted for destination therapy support, had a prior sternotomy, and had worse renal function than those living closer ( p <0.05 for all). After adjusting for these factors, albumin and center of implant, the hazard ratio did not reach statistical significance (hazard ratio = 1.2; p = 0.14). Except for gastrointestinal bleeding, the event rates for the secondary outcomes were higher for those living closer to the implanting center. Protocols should be designed for more frequent follow-up and increased shared care opportunities to ensure optimal outcomes are achieved in distant patients.

Continuous-flow left ventricular assist devices (CF-LVADs) have revolutionized the management of patients with advanced heart failure. Alternative implant strategies are increasingly used for device placement. We reviewed our experience from the Mechanical Circulatory Support Research Network registry with the HeartWare centrifugal CF-LVAD (HVAD). From May 2004 to August 2015, 1,150 patients underwent primary CF-LVAD implantation at our institutions. Within this group, a total of 283 patients (25%) were implanted with the HVAD. A minimally invasive left lateral thoracotomy (MILT) implant strategy was used in 53 patients (20%), of which 22 (42%) were implanted off-pump. Median age at implant was 59 years and 183 patients (65%) were implanted as bridge-to-transplantation. Follow-up was 100% complete for a total of 302 patient-years of support. In-hospital mortality was 4.9% (14 patients), and was comparable between the conventional sternotomy (CS) and MILT cohorts (p = 0.15). Patients in the MILT cohort had a shorter median length of stay (p < 0.01) and had a lower incidence of postimplant pump thrombus (p = 0.02). Cumulative survival at the end of follow-up reached 84%, and was comparable between the two groups (p = 0.298). Multivariate analysis identified preoperative bilirubin level as the only independent predictor of survival. Surgical technique had no impact on survival. In this large, multicenter experience, data demonstrate excellent survival and adverse event profiles for patients supported with the HVAD technology, regardless of surgical implant technique. With constant advancements in device technology along with our increasing clinical experience with the newer techniques, minimally invasive LVAD implantation continues to evolve as a valuable alternative to CS in selected patients.

Guidelines for performing concomitant procedures (CPs) in patients undergoing continuous flow-left ventricular assist device (CF-LVAD) implantation are unclear. The impact of an increased surgical complexity outside the constraint of landmark clinical trials has not been reported. From May 2004 to December 2013, 614 patients (499 males, 81%) underwent CF-LVAD implant at our institutions. Median age was 57 ± 13 years and 364 (59%) were bridge to transplantation (BTT). Survival and device-related complications were analyzed and stratified based on the surgical intervention. A total of 398 patients (65%) underwent CF-LVAD implantation without CPs. The remaining patients (35%, n = 216) were grouped according to various CPs. Survival was comparable between groups and not influenced by the CP, device type, or indication for implant. Time-to-first device-related adverse event was shorter in patients with CPs. Regression analysis revealed only increased age (p = 0.03), increase in baseline creatinine (p = 0.002), cardiopulmonary bypass time (p = 0.03), and decreased body mass index (p = 0.03) were predictors of mortality, whereas only age (p = 0.006) and prior sternotomy (p = 0.02) were related to adverse device-related events. Performing CPs leads to comparable survival and device-related outcomes after implant. The decision to perform CPs should be balanced with age, preoperative renal dysfunction, and projected complexity of surgery.