Although the long-term group showed a trend of having a lower prevalence of ischemic HF, the survival rates of patients with and without a history of ischemic HF were very similar at 3 years (87.3% vs. 90.3%). Similarly, despite trends for more women and nonwhite patients in the long-term cohort, the survival at 3 years was not different when patients were divided by sex (90.4% vs. 88.9% for men vs. women) and race (90.3% vs. 89.0% for whites vs. nonwhites).
This retrospective multicenter analysis of the BTT + CAP data set examines the pump performance and patient outcomes associated with over 2 years of HVAD support. The results of the entire BTT + CAP cohort (N = 382) were also presented as a representative BTT population and 79.4% of the patients were alive on HVAD support or transplanted after 2 years. The full patient cohort showed improvements in QoL in the first year similar to what was previously published by Slaughter et al.9
The long-term cohort of 74 patients had an average of 1,045 ± 229 days of support, which is greater than the average time on device in previous HVAD studies.9,11 Only 10 (13.5%) of the long-term patients had a pump exchange within the first 2 years after HVAD implant with an additional two patients having a pump exchange after the 2 year time point. The rate of driveline infections in this cohort was 0.18 EPPY, which is similar to the rates reported for the other commercially available LVAD in the BTT or DT settings.12,13 The long-term group also demonstrated significant and sustained improvements in QoL through the 3 year time point (Table 2).
Although the 74 patients with over 2 years of support had promising outcomes, the authors acknowledge the inherent bias in the long-term cohort, as inclusion in this group was conditional on having already survived 2 years of HVAD support. In general, their baseline characteristics appeared similar to the general BTT patient population. The trend for higher IPP categorization in the long-term patients suggests that they may have had less severe HF at baseline, which could have contributed to their improved outcomes.14 However, their lower mean blood pressure at baseline would be a bias in the opposite direction. The long-term group also had lower rates of severe adverse events that negatively affect LVAD survival.4,15–18 Finally, the significant differences in event profiles between the near- and long-term groups may be exaggerated as the incidence of events is generally higher in the period soon after implantation.19
With consideration of the bias in the long-term group, there was a large discrepancy in the rates of transplants for the patients who remained on long-term HVAD support. In the entire 382 patient group, 182 (48%) received a heart transplant within the first 2 years. Of the 74 patients in the long-term group, only 10 (13.5%) received a transplant while 47 (64%) are still on the transplant wait list and 27 patients are no longer listed. The most frequent reasons for delisting were BMI/weight contraindications (N = 7) and patient decision/refusal (N = 6). The majority of the long-term patients had blood type O, reflecting the known lower heart transplant rate of individuals with that blood type.20 There was also a larger fraction of women in the long-term cohort, and previous reports show women are less likely to be listed for heart transplantation.21,22 Fortunately, 73.4% of the women in the long-term group were either alive on original device or after exchange 3 years post-HVAD implant, which was no different from the men (77.5%). In a previous report, there were also no significant differences in post-LVAD mortality between men and women.23 Taken together, this suggests that the HVAD system is a viable solution for long-term support of women with advanced HF.
As mentioned in the discussion, the analysis of a subset of the BTT + CAP patients who had over 2 years of support may have introduced an inherent selection bias resulting in the favorable adverse event and survival outcomes. The near-term group had a large number of patients supported for shorter durations, whereas the long-term group had fewer patients each with a sustained period of support. Although the overall patient years of support are similar, the increased risk of adverse events immediately postimplantation could have contributed to the superior adverse event profile of the long-term group.19 Although we present potential reasons why patients remained on HVAD support after 2 years, other factors such as listing status over time, socioeconomic factors, and geographic variations could have played a role as well. No comparison were made with patients treated with the other commercially available continuous flow device. The ENDURANCE Supplemental trial, a prospective randomized trial comparing outcomes of patients receiving the HVAD versus the HeartMate II (Thoratec Corp., Pleasanton, CA) for DT (https://clinicaltrials.gov/ct2/show/NCT01966458) will allow for a more complete analysis of the long-term performance of both pumps.
Seventy-four of the 382 patients from the HeartWare BTT + CAP trial have exceeded 2 years of HVAD support with nine patients currently supported for at least 5 years. In addition, in the complete BTT + CAP cohort, nearly 80% of the 382 patients were transplanted or alive on device after 2 years. The long-term group generally had low incidences of adverse events and sustained improvements in QoL profiles. Women comprised a larger than normal fraction of the long-term patient population, and their outcomes were positive with no significant difference in mortality compared with the men. In conclusion, the favorable outcomes and stable QoL of patients with over 2 years of support suggest that the HVAD system deserves consideration when extended MCS may be required.
The authors acknowledge Mary V. Jacoski and Ming-Jay Chow, HeartWare Inc., for their assistance in the analysis and preparation of the manuscript.
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long-term support; mechanical circulatory support; patient outcomes; HVAD