Risk Stratification and Clinical Consequences of Cardiopulmonary Exercise Testing and Cardiac Rehabilitation Outcomes Following Heart Transplantation
2018-10
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Risk Stratification and Clinical Consequences of Cardiopulmonary Exercise Testing and Cardiac Rehabilitation Outcomes Following Heart Transplantation
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2018-10
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Heart transplantation continues to be considered the gold standard treatment for end-stage heart failure. The cardiopulmonary exercise testing (CPET) metrics of peak oxygen consumption (VO2peak) and ventilatory efficiency (VE/VCO2 slope) have gained significant merit as prognostic markers in various populations. The first aim of this dissertation focused on the potential influence of sex-specific characteristics in cardiopulmonary exercise metrics in heart transplant patients. Heart transplant patients with CPET between 2007-2016 were assessed for VO2peak and VE/VCO2 slope prior to and following heart transplantation. Delta change in VO2peak (M: 5.0±4.8 vs. W: 5.3±4.9 mL/kg/min, p=0.85) and VE/VCO2 slope (M: -5±11 vs. W: -9±17, p=0.29) were not different between sexes. Importantly, women improved their VO2peak and VE/VCO2 slope to a similar degree compared to men, in contrast to previous work in heart failure patients. As VO2peak is an important metric for transplant eligibility, this prognostic parameter was further evaluated in the second aim of this dissertation to investigate possible predictors of VO2peak following transplantation. Univariate and multivariate logistic regression analyses were created to determine predictors of heart transplant patients with the highest post-HTx VO2peak (i.e. quartile 4: VO2peak >20.1 mL/kg/min). Cardiac rehabilitation (CR) exercise sessions (OR: 1.10, 95% CI: 1.03-1.16, p=0.002) and pre-transplant VO2peak (OR: 1.16, 95% CI: 1.04-1.30, p=0.007) were independently predictive of higher VO2peak following transplant. These data highlight the importance of CR attendance and prior fitness in predicting VO2peak in heart transplant patients. To further elucidate CR involvement and long-term outcomes, the third aim of this dissertation was to evaluate its role in reducing major adverse cardiac events (MACE). CR exercise sessions were assessed as a binary variable by recursive partitioning model as ≥23 or <23 sessions attended. Passive follow-up was performed for the composite end-point of MACE defined as stroke, percutaneous intervention, heart failure, myocardial infarction, acute rejection, and/or all-cause mortality. Mean follow-up was 4.1±2.7 years and 44 patients (31%) had an event: Stroke (n=1), PCI (n=5), HF (n=6), MI (n=1), rejection (n=16), or death (n=15). Exercise sessions was a significant predictor of MACE with ≥23 sessions associated with a 60% reduction in MACE risk (HR: 0.42, 95% CI: 0.19-0.94, p=0.035). This remained constant after covariate adjustment models. In heart transplant patients, CR was associated with a decreased risk of MACE and should be viewed as a critical tool in the post-transplant treatment strategy to maximize positive outcomes. The role of cardiorespiratory fitness maintenance and evaluation, specifically in the setting of postoperative cardiac rehabilitation participation, plays an essential role in heart transplantation treatment and long-term survival.
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University of Minnesota Ph.D. dissertation. October 2018. Major: Kinesiology. Advisor: Donald Dengel. 1 computer file (PDF); vii, 113 pages.
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Nyberg, Katelyn. (2018). Risk Stratification and Clinical Consequences of Cardiopulmonary Exercise Testing and Cardiac Rehabilitation Outcomes Following Heart Transplantation. Retrieved from the University Digital Conservancy, https://hdl.handle.net/11299/201675.
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