Allison, Thomas

Abstract Introduction Cardiopulmonary exercise testing (CPET) parameters such as peak VO2 ≤ 14ml/kg/min, percentage predicted peak VO2 (ppVO2) ≤ 50% and ventilation equivalent of carbon dioxide (Ve/VCO2) >35 l/min/l/min are recommended thresholds to list for isolated heart transplant. There is minimal data on clinical events after listing to guide clinical management or priority in organ allocation. Purpose To assess the effect of peak VO2, ppVO2, Ve/VCO2 on clinical events after listing for isolated heart transplant. Methods In a single centre retrospective study, we identified patients who were status 6 or status 2 prior to 2018 at time of listing for isolated heart transplant between 2007 and 2021. Clinical data were collected by chart review. Primary outcome of progressive heart failure was defined as death or upgrade in transplant priority status (new inotropes or mechanical circulatory support). Comparison was made between peak VO2 strata (> 14 vs ≤ 14 ml/kg/min), ppVO2 strata (> 50% vs 40-50% vs <40%) and Ve/VCO2 strata (<35 vs >35 l/min/l/min). Secondary outcome was time dependent survival after listing for heart transplant. Results We identified 141 patients of which 133 underwent CPET and follow up was available for 130 who were included in the analysis. Median age was 53 years (interquartile range 41-59 years), 29.1% of patients were female. Median peak VO2 was 14.0 ml/kg/min (11.2-15.7), ppVO2 was 44% (36-52), Ve/VCO2 slope was 34.0 (31.0-37.0) and RER was 1.1 (1.1-1.2). 87 patients had progressive heart failure consisting of 34 deaths and 83 patients having upgrade in priority status. There was a significant difference in risk of progressive heart failure comparing peak VO2 strata (Figure 1) (freedom from event at one year 71.4% with peak VO2 > 14 vs 46.5% with peak VO2 ≤ 14, p=0.00061) and ppVO2 strata (Figure 2) (freedom from event at one year 75.0% with ppVO2 >50% vs 61.2% with ppVO2 40-50% vs 42.6% with ppVO2 <40%, p=0.0015). There was no significant difference with Ve/VCO2 strata (freedom from event at one year 59.8% with Ve/VCO2 <34 vs 54.9% with Ve/VCO2 >34, p=0.52). There were 34 deaths before transplant and 23 deaths after transplant. 87 patients underwent transplant. In a time dependent survival analysis, age, gender and ppVO2<50% (HR 1.65 (0.87-3.12)) were not significant predictors of mortality. Both early transplant (defined as < 1 year after listing, HR 0.14 (0.06-0.34) and late transplant (defined as > 1 year after listing, HR 0.16 (0.08-0.32)) were significant predictors of lower mortality whilst Ve/VCO2>35 (HR 2.09 (1.19-3.68)) was a significant predictor of higher mortality. Conclusions Peak VO2 and ppVO2 stratify risk of progressive heart failure in ambulatory patients awaiting isolated heart transplant. However, Ve/VCO2 is a predictor of significantly higher mortality. These findings should affect clinical management and transplant priority status; and influence revision of future guidelines.Freedom from event by peak VO2 strataFreedom from event by ppVO2 strata

Tomas Konecny, 2012 Finalist and Presenting Author

Abstract Introduction Cardiopulmonary exercise testing (CPET) is an important diagnostic method to evaluate athletes and non-athletes, however we do not have widely accepted normal values for correct evaluation and interpretation in the young. Goals Our aim was to compare CPET parameters of young athletes and non-athletes and determine reference values. Methods Exercise tests were performed in young non-athletes, aged <18 years between 2011 to 2016 at Mayo Clinic. Athletes underwent detailed sports cardiology screening including CPET at Semmelweis University Heart and Vascular Center between 2016 and 2018. Individuals with cardiovascular disease were excluded. We created 2 subgroups in both sexes: 12–14 years (Group 1), 15–17 years (Group 2). Statistical analysis was performed using SAS with analysis of variance under the general linear model adjusting for age, body mass index and test effort based on peak respiratory exchange ratio (RER). Results A total of 212 athletes (92% male, 15.5±0.6ys) and 207 non-athletes (68% male, 15.0±0.7ys) were included in the analysis. In Group 1 boys, athletes have higher peak HR (200.0±9.2 vs 188.5±16.8 bpm, p<0.0001), HR reserve (117.1±14.5 vs 108.9±19.8 bpm p<0.05), VO2 max (53.7±6.6 vs 44.7±9.1 mL/kg/min p<0.0001), ventilation (VE) (120.3±25.0 vs 70.7±21.6 L/min p<0.0001) and RER (1.12±0.0 vs 1.07±0.08, p <.001) compared to controls. In Group 2 boys, there was no difference in peak HR and HR reserve, but athletes have higher VO2 max (57.2±4.7 vs 45.3±9.3 mL/kg/min, p<0.0001) and VE (150.7±23.7 vs 104.1±25.9 L/min, p<0.0001), similarly as Group 2 girls: VO2 max (46.3±3.6 vs 34.9±8.5 mL/kg/min p<0.0001), VE (118.7±12.5 vs 68.4±20.6 L/min, p<0.0001). In male athletes, peak HR (200.6±9.2 vs 196.5±7.4 bpm p<0.05) and HR recovery (34.2±9.8 vs 29.8±11.1 bpm p<0.05) decreases with age, while VO2 max (53.7±6.6 vs 57.2±4.7 mL/kg/min, p<0.001) and VE (120.3±24.9 vs 150.7±23.7 L/min, p<0.0001) increases. Lower cut-off values were determined in each group (Figure). Lower-cut off values Conclusion We created a unique Mayo-Semmelweis database of young athletes and non-athletes. As a result of intensive training, athletes show higher levels of CPET variables vs non-athletes. Our study provides CPET reference values in the pediatric age group, applying them could contribute to correct evaluation and interpretation of CPET, increasing its diagnostic potential.