Revisiting a Prognosticating Algorithm from Cardiopulmonary Exercise Testing in Chronic Heart Failure (from the MECKI Score Population).

Cardiopulmonary exercise testing is a prognostic tool in heart failure with reduced left ventricular ejection fraction (HFrEF). Prognosticating algorithms have been proposed, but none has been validated. In 2017, a predictive algorithm, based on peak oxygen consumption (VO2), ventilatory response to exercise (ventilation [VE] carbon dioxide production [VCO2], the VE/VCO2 slope), exertional oscillatory ventilation (EOV), and peak respiratory exchange ratio, was recommended, according treatment with ß blockers: patients with HFrEF registered in the metabolic exercise test data combined with cardiac and kidney indexes (MECKIs) database were used to validated this algorithm. According to the inclusion/exclusion criteria, 4,683 MECKI patients with HFrEF were enrolled. At 3 years follow-up, the end point was cardiovascular death and urgent heart transplantation (cardiovascular events [CV]). CV events occurred in 25% in patients without ß blockers, whereas those with ß-blockers had 11% (p <0.0001). In patients without ß blockers, 36%, 24%, and 7% CV events were observed in those with peak VO2 ≤10, with peak VO2 >10 <18, and with peak VO2 ≥18 ml/kg/min (p = 0.0001), respectively; in MECKI patients with peak VO2 ≤10 and patients with intermediate exercise capacity, a peak respiratory exchange ratio (≥1.15) and VE/VCO2 slope (≥35) were diriment, respectively (p = 0.0001). EOV, when occurred, increased risk. In MECKI patients on ß blockers, 29%, 17%, and 8% CV events were noticed in those with a peak VO2 ≤8, with peak VO2 = 8 to 12, and patients with peak VO2 ≥12 ml/kg/min, respectively (p = 0.0000); when EOV was monitored an increment of risk was witnessed. In conclusion, the outcome of this algorithm was confirmed with the MECKI cohort.

Pick Your Threshold: A Comparison Among Different Methods of Anaerobic Threshold Evaluation in Heart Failure Prognostic Assessment.

BACKGROUND: In clinical practice, anaerobic threshold (AT) is used to guide training and rehabilitation programs, to define risk of major thoracic or abdominal surgery, and to assess prognosis in heart failure (HF). AT of oxygen uptake (V.O2; V.O2AT) has been reported as an absolute value (V.O2ATabs), as a percentage of predicted peak V.O2 (V.O2AT%peak_pred), or as a percentage of observed peak V.O2 (V.O2AT%peak_obs). A direct comparison of the prognostic power among these different ways to report AT is missing. RESEARCH QUESTION: What is the prognostic power of these different ways to report AT? STUDY DESIGN AND METHODS: In this observational cohort study, we screened data of 7,746 patients with HF with a history of reduced ejection fraction (< 40%) recruited between 1998 and 2020 and enrolled in the Metabolic Exercise Combined With Cardiac and Kidney Indexes register. All patients underwent a maximum cardiopulmonary exercise test, executed using a ramp protocol on an electronically braked cycle ergometer. RESULTS: This study considered 6,157 patients with HF with identified AT. Follow-up was median, 4.2 years (25th-75th percentiles, 1.9-5.0 years). Both V.O2ATabs (mean ± SD, 823 ± 305 mL/min) and V.O2AT%peak_pred (mean ± SD, 39.6 ± 13.9%), but not V.O2AT%peak_obs (mean ± SD, 69.2 ± 17.7%), well stratified the population regarding prognosis (composite end point: cardiovascular death, urgent heart transplant, or left ventricular assist device). Comparing area under the receiver operating characteristic curve (AUC) values, V.O2ATabs (0.680) and V.O2AT%peak_pred (0.688) performed similarly, whereas V.O2AT%peak_obs (0.538) was significantly weaker (P < .001). Moreover, the V.O2AT%peak_pred AUC value was the only one performing as well as the AUC based on peak V.O2 (0.710), with an even a higher AUC (0.637 vs 0.618, respectively) in the group with severe HF (peak V.O2 < 12 mL/min/kg). Finally, the combination of V.O2AT%peak_pred with peak V.O2 and V. per CO2 production shows the highest prognostic power. INTERPRETATION: In HF, V.O2AT%peak_pred is the best way to report V.O2 at AT in relationship to prognosis, with a prognostic power comparable to that of peak V.O2 and, remarkably, in patients with severe HF.

Brisk walking can be a maximal effort in heart failure patients: a comparison of cardiopulmonary exercise and 6 min walking test cardiorespiratory data.

AIMS: Cardiopulmonary exercise test (CPET) and 6 min walking test (6MWT) are frequently used in heart failure (HF). CPET is a maximal exercise, whereas 6MWT is a self-selected constant load test usually considered a submaximal, and therefore safer, exercise, but this has not been tested previously. The aim of this study was to compare the cardiorespiratory parameters collected during CPET and 6MWT in a large group of healthy subjects and patients with HF of different severity. METHODS AND RESULTS: Subjects performed a standard maximal CPET and a 6MWT wearing a portable device allowing breath-by-breath measurement of cardiorespiratory parameters. HF patients were grouped according to their CPET peak oxygen uptake (peakV̇O2 ). One hundred and fifty-five subjects were enrolled, of whom 40 were healthy (59 ± 8 years; male 67%) and 115 were HF patients (69 ± 10 years; male 80%; left ventricular ejection fraction 34.6 ± 12.0%). CPET peakV̇O2 was 13.5 ± 3.5 mL/kg/min in HF patients and 28.1 ± 7.4 mL/kg/min in healthy subjects (P < 0.001). 6MWT-V̇O2 was 98 ± 20% of the CPET peakV̇O2 values in HF patients, while 72 ± 20% in healthy subjects (P < 0.001). 6MWT-V̇O2 was >110% of CPET peakV̇O2 in 42% of more severe HF patients (peakV̇O2  < 12 mL/kg/min). Similar results have been found for ventilation and heart rate. Of note, the slope of the relationship between V̇O2 at 6MWT, reported as a percentage of CPET peakV̇O2 vs. 6MWT V̇O2 reported as the absolute value, progressively increased as exercise limitation did. CONCLUSIONS: In conclusion, the last minute of 6MWT must be perceived as a maximal or even supramaximal exercise activity in patients with more severe HF. Our findings should influence the safety procedures needed for the 6MWT in HF.