Cardiopulmonary exercise testing; do circulatory and ventilatory power predict cardiovascular outcomes in patients with heart failure

Background Cardiopulmonary exercise testing (CPET) has an important role in mortality prediction in heart failure (HF) and patient selection for heart transplant. New indices as circulatory power (CP) and ventilatory power (VP) have been proposed as predictors of cardiac events. In addition, VP predicts mean pulmonary artery pressure (mPAP) in patients with pulmonary arterial hypertension. Purpose We aimed to analyse the prognostic value of classic and new CPET variables in patients with HF. Methods We retrospectively assessed consecutive patients with HF who underwent CPET in a single-centre between 2013 and 2017. New CPET variables were collected: CP was defined as the product of peak O2 uptake and peak systolic blood pressure (SBP), while VP was defined as peak SBP divided by the minute ventilation–CO2 production (VE/VCO2) slope. The primary endpoint was a composite of all-cause mortality, heart transplant, or HF hospitalization. Survival analysis was performed using Kaplan-Meier curves and multivariable Cox regression. Results Overall, 216 patients (mean age 55.4±10.9, 77.3% male) were included, 38.4% with ischemic HF, and mean left ventricle ejection fraction (LVEF) 30±14%. Most patients were evaluated through the modified Naughton (76.3%), the original Naughton (19.0%), and Bruce protocols (4.7%). Regarding classic CPET variables: mean pVO2 16.8±6.0 mL O2 kg–1 min–1, mean percent-predicted pVO2 62.6±23.9%, median VE/VCO2 slope 37.3 [32.6–44.5], exercise oscillatory ventilation (EOV) present in 13.9%, resting partial pressure of end-tidal carbon dioxide (PETCO2) ≥33 mmHg with an increase of 3–8 mmhg during exercise in 17.1%, and mean peak SBP 128.8±27.2 mmHg. Median circulatory power was 1927 [1404–2694] mmHg·min/mL/kg and mean ventilatory power 3.47±1.32 mmHg. After a median follow-up of 5 [4–6] years, the primary endpoint occurred in 66.2% of patients (rehospitalization, heart transplant, and all-cause death occurred in 57.0%, 25.9%, and 32.4%, respectively). In Cox regression multivariate analysis, the primary endpoint was predicted by pVO2 (HR 0.90, 95% CI: 0.87–0.93), percent-predicted pVO2 (HR 0.97, 95% CI: 0.96–0.98), VE/VCO2 slope (HR 1.04, 95% CI: 1.03–1.06), VP (HR 0.62, 95% CI: 0.52–0.73) but not CP (HR 0.99, 95% CI: 0.98–1.01). Kaplan-Meier curves according to the LVEF are depicted in Fig. 1A. ROC analysis (Fig. 1B) revealed that VP (AUC 0.768) has higher discriminative power for the primary endpoint, compared to pVO2 (AUC 0.741). One hundred and twenty-seven patients also underwent right heart catheterization: mean mPAP was 30.6±12.9 and it was not correlated with VP (r=−0.06, p=0.47). Conclusion CPET variables are good predictors of all-cause mortality, heart transplant, or HF hospitalization. Ventilatory power (but not circulatory power) is an additional useful variable in event prediction. On the other hand, VP is not correlated with mPAP in patients with HF. FUNDunding Acknowledgement Type of funding sources: None.

Reduction of functional cardiovascular reserve in the stages of chronic kidney disease

SUMMARY OBJECTIVE Patients with chronic kidney disease (CKD) present reduced oxygen consumption at peak exercise (VO2 peak). No studies have evaluated objective measures of the cardiovascular reserve, besides VO2 peak and VO2 at the anaerobic threshold (VO2 AT), and compared these measures among ckd patients at different stages of the disease. METHODS Fifty-eight patients [pre-dialysis group (PD)=26, hemodialysis group (HD)=20, and post-kidney transplant group (KT)=12] were included. The following measures of cardiovascular reserve were obtained: 1) peak heart rate (HR); 2) peak systolic blood pressure (SBP); 3) VO2 peak and % predicted; 4) VO2 AT and % of predicted VO2; 5) peak circulatory power; 6) ventilatory efficiency for the production of carbon dioxide (VE/VCO2 slope); 7) oxygen uptake efficiency slope (OUES); and 8) recovery of gas exchange. RESULTS The VO2 peak and VO2 AT in the PD, HD, and KT groups were reduced to 86% and 69%, 70% and 57%, and 79% and 64% of the predicted value, respectively. Patients in the HD group had lower VO2 peak (17.5±5.9 vs. 23.2±8.2 [p-value=0.036]) and VO2 AT (14.0±5.2 vs. 18.3±4.7 [p-value=0.039]) compared to patients in the KT group. OUES was significantly lower in the HD group compared to the KT group (p-value=0.034). Age in the PD, HD, and KT groups and sedentary lifestyle in the KT group were predictors of VO2 peak. CONCLUSIONS CKD patients presented a reduction in cardiovascular reserve regardless of the stage of the disease. However, hemodialysis patients presented a greater reduction of cardiovascular reserve when compared to post-kidney transplant patients.

CARDIOPULMONARY EXERCISE TEST IN TYPE 2 DIABETES MELLITUS IN ABSENCE OF CHRONIC HEART FAILURE: REDUCED LUNG AND HEART FUNCTION

Comparar a tolerância ao exercício, funções respiratória e cardiovascular entre indivíduos não diabéticos e diabéticos tipo 2 sem doenças crônicas cardíacas. Treze homens normoglicêmicos (NDG) e oito homens diabéticos tipo 2 (DG) que realizaram um teste cardiopulmonar de esforço (TCPE) em uma esteira motorizada (o teste iniciou-se em 3km.h-1 com incremento de 1km.h-1 a cada dois minutos) que avaliou a função respiratória, parâmetros cardiovasculares e tolerância ao exercício. Valores de consumo de oxigênio e intensidades na intensidade do limiar ventilatório foram significativamente menores para o DG (DG: 5,6 ± 0,5 km/h-1 e 13,1 ± 3,8 ml.(kg.min)-1; NDG: 6,5 ± 0,5 km/h-1 e 16,4 ± 2,8 ml.(kg.min)-1; p < 0,05). Consumo de oxigênio pico e intensidade associada foram significativamente menores para o DG (DG: 22,7 ± 5,7 ml.(kg.min)-1; 8,2 km/h-1 ± 0,7 km/h-1) quando comparado com o NDG (30,8 ± 5,4 ml.(kg.min)-1; 11,6 ± 1,5 km/h). Oxygen uptake efficiency slope (OUES) e circulatory power foram significativamente menores para o DG (p < 0,05) embora não foram encontradas diferenças significativas na eficiência ventilatória. Em indivíduos portadores de diabetes tipo 2, mesmo sem a presença conhecida de doenças cardiovasculares, apresentaram menores níveis de condicionamento cardiorrespiratório e tolerância ao exercício. Circulatory power pico e OUES também foram reduzidos nesses indivíduos.

Circulatory power and ventilatory power over time under goal-oriented sequential combination therapy for pulmonary arterial hypertension

Many therapeutic options are available for patients with pulmonary arterial hypertension (PAH). However, little is known about the effects of sequential combination therapy on exercise capacity. Here we monitored exercise capacity by cardiopulmonary exercise testing (CPX) and observed the benefit of using a peak VO2 cutoff of 15 mL/kg/min to guide combination therapy. Thirty patients newly diagnosed with PAH were treated with goal-oriented sequential combination therapy. Endothelin receptor antagonists (ERA) were the first-line treatment, with phosphodiesterase type 5 inhibitors (PDE-5i) as the preferred combination partner. The patients underwent cardiac catheterization at baseline and after 12 months and CPX at baseline and after three, six, and 12 months. Circulatory power (CP) was defined as the product of peak O2 uptake and peak systolic blood pressure (SBP); ventilatory power (VP) was defined as peak SBP divided by the minute ventilation–CO2 production slope. After 12 months, ERA had been administered to 100% of the study patients and PDE-5i to 82%. Mean CP at baseline and after three, six, and 12 months was 1807, 2063, 2248, and 2245 mmHg·min/mL/kg, respectively, and mean VP was 2.93, 3.53, 4.16, and 3.68 mmHg, respectively. CP was greater after 6 months than at baseline ( P = 0.047); VP was greater after three months than at baseline ( P = 0.019) and further improved at six months compared with three months ( P = 0.040). Therefore, repeated CPX assessment, including measurement of CP and VP, can provide useful information regarding the efficacy of goal-oriented treatment for PAH.