Post-transplant survival with pre-transplant durable continuous-flow mechanical circulatory support in a Swiss cohort of heart transplant recipients.

BACKGROUND: Worldwide, almost half of all heart transplantation candidates arrive today at their transplant operation with durable continuous-flow mechanical circulatory support (CF-MCS). This evolution is due to a progressive increase of waiting list time and hence an increased risk of haemodynamic worsening. Longer duration of CF-MCS is associated with a higher risk of device-related complications with potential adverse impact on post-transplant outcome as suggested by recent results from the United Network of Organ Sharing of the United States. METHODS: A 2-centre Swiss heart transplantation programme conducted a retrospective observational study of consecutive patients of theirs who underwent a transplant in the period 2008-2020. The primary aim was to determine whether post-transplant all-cause mortality is different between heart transplant recipients without or with pre-transplant CF-MCS. The secondary outcome was the acute cellular rejection score within the first year post-transplant. RESULTS: The study participants had a median age of 54 years; 38/158 (24%) were females. 53/158 study participants (34%) had pre-transplant CF-MCS with a median treatment duration of 280 days. In heart transplant recipients with pre-transplant CF-MCS, the prevalence of ischaemic cardiomyopathy was higher (51 vs 32%; p = 0.013), the left ventricular ejection fraction was lower (20 vs 25; p = 0.047) and pulmonary vascular resistance was higher (2.3 vs 2.1 Wood Units; p = 0.047). Over the study period, the proportion of heart transplant recipients with pre-transplant CF-MCS and the duration of pre-transplant CF-MCS treatment increased (2008-2014 vs 2015-2020: 22% vs 45%, p = 0.009; increase of treatment days per year: 34.4 ± 11.2 days, p = 0.003; respectively). The primary and secondary outcomes were not different between heart transplant recipients with pre-transplant CF-MCS or direct heart transplantation (log-rank p = 0.515; 0.16 vs 0.14, respectively; p = 0.81). CONCLUSION: This data indicates that the strategy of pre-transplant CF-MCS with subsequent orthotopic heart transplantation provides post-transplant outcomes not different to direct heart transplantation despite the fact that the duration of pre-transplant assist device treatment has progressively increased.

Fat Oxidation Kinetics Is Related to Muscle Deoxygenation Kinetics During Exercise.

PURPOSE: The present study aimed to determine whether whole-body fat oxidation and muscle deoxygenation kinetics parameters during exercise were related in individuals with different aerobic fitness levels. METHODS: Eleven cyclists [peak oxygen uptake ( V . O 2 ⁢ p ⁢ e ⁢ a ⁢ k ): 64.9 ± 3.9 mL⋅kg-1⋅min-1] and 11 active individuals ( V . O 2 ⁢ p ⁢ e ⁢ a ⁢ k : 49.1 ± 7.4 mL⋅kg-1⋅min-1) performed a maximal incremental cycling test to determine V . O 2 ⁢ p ⁢ e ⁢ a ⁢ k and a submaximal incremental cycling test to assess whole-body fat oxidation using indirect calorimetry and muscle deoxygenation kinetics of the vastus lateralis (VL) using near-infrared spectroscopy (NIRS). A sinusoidal (SIN) model was used to characterize fat oxidation kinetics and to determine the intensity (Fatmax) eliciting maximal fat oxidation (MFO). The muscle deoxygenation response was fitted with a double linear model. The slope of the first parts of the kinetics (a 1) and the breakpoint ([HHb]BP) were determined. RESULTS: MFO (p = 0.01) and absolute fat oxidation rates between 20 and 65% V . O 2 ⁢ p ⁢ e ⁢ a ⁢ k were higher in cyclists than in active participants (p < 0.05), while Fatmax occurred at a higher absolute exercise intensity (p = 0.01). a 1 was lower in cyclists (p = 0.02) and [HHb]BP occurred at a higher absolute intensity (p < 0.001) than in active individuals. V . O 2 ⁢ p ⁢ e ⁢ a ⁢ k was strongly correlated with MFO, Fatmax, and [HHb]BP (r = 0.65-0.88, p ≤ 0.001). MFO and Fatmax were both correlated with [HHb]BP (r = 0.66, p = 0.01 and r = 0.68, p < 0.001, respectively) and tended to be negatively correlated with a 1 (r = -0.41, p = 0.06 for both). CONCLUSION: This study showed that whole-body fat oxidation and muscle deoxygenation kinetics were both related to aerobic fitness and that a relationship between the two kinetics exists. Individuals with greater aerobic fitness may have a delayed reliance on glycolytic metabolism at higher exercise intensities because of a longer maintained balance between O2 delivery and consumption supporting higher fat oxidation rates.