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.

The double anaerobic threshold in heart failure: MECKI score database overview.

AIMS: In heart failure (HF), anaerobic threshold (AT) may be indeterminable but its value held a relevant prognostic role. AT is evaluated joining three methods: V-slope, ventilatory equivalent, and end-tidal methods. The possible non-concordance between the V-slope (met AT) and the other two methods (vent AT) has been highlighted in healthy individuals and named double threshold (DT). METHODS AND RESULTS: We reanalysed 1075 cardiopulmonary exercise tests of HF patients recruited in the Metabolic Exercise test data combined with Cardiac and Kidney Indexes (MECKI) score database. We identified DT in 43% of cases. Met AT precedes vent AT being met-ventΔVO2 221 (interquartile range: 129-319) mL/min. Peak VO2 , 1307 ± 485 vs. 1343 ± 446 mL/min (63 ± 17 vs. 63 ± 17 percentage of predicted), was similar between DT+ and DT- patients. Differently, DT+ showed a lower ventilatory vs. carbon dioxide production (VE/VCO2 ) slope (29.6 ± 6.1 vs. 31.0 ± 6.3), a lower peak exercise end-tidal oxygen tension (PetO2 ) 115.3 (111.5-118.9) vs. 116.4 (112.4-120.2) mmHg, and a higher carbon dioxide tension (PetCO2 ) 34.2 (30.9-37.1) vs. 32.4 (28.7-35.5) mmHg. Vent AT showed a significant higher VO2 , 957 ± 318 vs. 719 ± 252 mL/min, VCO2 , 939 ± 319 vs. 627 ± 226 mL/min, ventilation, 31.0 ± 8.3 vs. 22.5 ± 6.3 L/min, respiratory exchange ratio, 0.98 ± 0.08 vs. 0.87 ± 0.07, PetO2 , 108 (104-112) vs. 105 (101-109) mmHg, PetCO2 , 37 (34-40) vs. 36 (33-39) mmHg, and VE/VO2 ratio, 33.5 ± 6.7 vs. 32.6 ± 6.9, but lower VE/VCO2 ratio, 33 (30-37) vs. 36 (32-41), compared with met AT. At 2 year survival by Kaplan-Meier analysis, even adjusted for confounders, DT resulted not associated with survival. CONCLUSIONS: Double threshold is frequently observed in HF patients. DT+ is associated to a decreased ventilatory response during exercise.

ECG in dilated cardiomyopathy: specific findings and long-term prognostic significance.

OBJECTIVE: The objective was to provide an exhaustive characterization of ECG features in a large cohort of dilated cardiomyopathies (DCMs) and then investigate their possible prognostic role in the long term. BACKGROUND: ECG is an accessible, reproducible, low-cost diagnostic and prognostic tool. However, an extensive description of ECG features and their long-term prognostic role in a large cohort of DCM is lacking. METHODS: All available baseline ECGs of DCM patients enrolled from 1992 to 2013 were systematically analysed. Patients underwent to a complete clinical-laboratory evaluation. The study outcome measures were death or heart transplant (D/HT) and sudden death or malignant ventricular arrhythmias (SD/MVA). RESULTS: Four hundred and fourteen DCM patients were enrolled. During a median follow-up of 125 months, 55 and 57 patients experienced D/HT and SD/MVA, respectively. At multivariate analysis, left ventricular hypertrophy (P = 0.017), heart rate (HR, P = 0.005) and anterolateral T-wave inversion (P = 0.041) predicted D/HT. Regarding SD/MVA, S wave amplitude in V2 (P = 0.008), R wave amplitude in DIII (P = 0.007), anterolateral T-wave inversion (P = 0.017) emerged as predictors. At receiver-operating curve analyses, the addition of ECG models to the clinical-laboratory evaluation significantly increased the area under the curve both for D/HT (from 0.68 to 0.74, P = 0.042) and SD/MVA (from 0.70 to 0.77, P = 0.048). CONCLUSION: The exhaustive systematic evaluation of ECG has an incremental impact in the prognostication of a large cohort of DCM patients, also regarding the arrhythmic stratification.