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.

Gender and age normalization and ventilation efficiency during exercise in heart failure with reduced ejection fraction.

AIMS: Ventilation vs. carbon dioxide production (VE/VCO2 ) is among the strongest cardiopulmonary exercise testing prognostic parameters in heart failure (HF). It is usually reported as an absolute value. The current definition of normal VE/VCO2 slope values is inadequate, since it was built from small groups of subjects with a particularly limited number of women and elderly. We aimed to define VE/VCO2 slope prediction formulas in a sizable population and to test whether the prognostic power of VE/VCO2 slope in HF was different if expressed as a percentage of the predicted value or as an absolute value. METHODS AND RESULTS: We calculated the linear regressions between age and VE/VCO2 slope in 1136 healthy subjects (68% male, age 44.9 ± 14.5, range 13-83 years). We then applied age-adjusted and sex-adjusted formulas to predict VE/VCO2 slope to HF patients included in the metabolic exercise test data combined with cardiac and kidney indexes score database, which counts 6112 patients (82% male, age 61.4 ± 12.8, left ventricular ejection fraction 33.2 ± 10.5%, peakVO2 14.8 ± 4.9, mL/min/kg, VE/VCO2 slope 32.7 ± 7.7) from 24 HF centres. Finally, we evaluated whether the use of absolute values vs. percentages of predicted VE/VCO2 affected HF prognosis prediction (composite of cardiovascular mortality + urgent transplant or left ventricular assist device). We did so in the entire cardiac and kidney indexes score population and separately in HF patients with severe (peakVO2 < 14 mL/min/kg, n = 2919, 61.1 events/1000 pts/year) or moderate (peakVO2 ≥ 14 mL/min/kg, n = 3183, 19.9 events/1000 pts/year) HF. In the healthy population, we obtained the following equations: female, VE/VCO2 = 0.052 × Age + 23.808 (r = 0.192); male, VE/VCO2 = 0.095 × Age + 20.227 (r = 0.371) (P = 0.007). We applied these formulas to calculate the percentages of predicted VE/VCO2 values. The 2-year survival prognostic power of VE/VCO2 slope was strong, and it was similar if expressed as absolute value or as a percentage of predicted value (AUCs 0.686 and 0.690, respectively). In contrast, in severe HF patients, AUCs significantly differed between absolute values (0.637) and percentages of predicted values (0.650, P = 0.0026). Moreover, VE/VCO2 slope expressed as a percentage of predicted value allowed to reclassify 6.6% of peakVO2 < 14 mL/min/kg patients (net reclassification improvement = 0.066, P = 0.0015). CONCLUSIONS: The percentage of predicted VE/VCO2 slope value strengthens the prognostic power of VE/VCO2 in severe HF patients, and it should be preferred over the absolute value for HF prognostication. Furthermore, the widespread use of VE/VCO2 slope expressed as percentage of predicted value can improve our ability to identify HF patients at high risk, which is a goal of utmost clinical relevance.

Exercise oscillatory ventilation and prognosis in heart failure patients with reduced and mid-range ejection fraction.

AIMS: Exercise oscillatory ventilation (EOV) is a pivotal cardiopulmonary exercise test parameter for the prognostic evaluation of patients with chronic heart failure (HF). It has been described in patients with HF with reduced ejection fraction (<40%, HFrEF) and with HF with preserved ejection fraction (>50%, HFpEF), but no data are available for patients with HF with mid-range ejection fraction (40-49%, HFmrEF). The aim of the study was to evaluate the prognostic role of EOV in HFmrEF patients. METHODS AND RESULTS: We analysed 1239 patients with HFmrEF and 4482 patients with HFrEF, enrolled in the MECKI score database, with a 2-year follow-up. The study endpoint was the composite of cardiovascular death, urgent heart transplant, and ventricular assist device implantation. We identified EOV in 968 cases (16% and 17% of cases in HFmrEF and HFrEF, respectively). HFrEF EOV+ patients were significantly older, and their parameters suggested a more severe HF than HFrEF EOV- patients. A similar behaviour was found in HFmrEF EOV+ vs. EOV- patients. Kaplan-Meier analysis, irrespective of ejection fraction, showed that EOV is associated with a worse survival, and that patients with HFrEF and HFmrEF EOV+ had a significantly worse outcome than the EOV- of the same ejection fraction groups. EOV-associated survival differences in HFmrEF patients started after 18 months of follow-up. CONCLUSION: Exercise oscillatory ventilation has a similar prevalence and ominous prognostic value in both HFmrEF and HFrEF patients, indicating a group of patients in need of a more intensive follow-up and a more aggressive therapy. In HFmrEF, the survival curves between EOV+ and EOV- patients diverged only after 18 months.

Heart failure prognosis over time: how the prognostic role of oxygen consumption and ventilatory efficiency during exercise has changed in the last 20 years.

AIMS: Exercise-derived parameters, specifically peak exercise oxygen uptake (peak VO2 ) and minute ventilation/carbon dioxide relationship slope (VE/VCO2 slope), have a pivotal prognostic value in heart failure (HF). It is unknown how the prognostic threshold of peak VO2 and VE/VCO2 slope has changed over the last 20 years in parallel with HF prognosis improvement. METHODS AND RESULTS: Data from 6083 HF patients (81% male, age 61 ± 13 years), enrolled in the MECKI score database between 1993 and 2015, were retrospectively analysed. By enrolment year, four groups were generated: group 1 1993-2000 (n = 440), group 2 2001-2005 (n = 1288), group 3 2006-2010 (n = 2368), and group 4 2011-2015 (n = 1987). We compared the 10-year survival of groups and analysed how the overall risk (cardiovascular death, urgent heart transplantation, or left ventricular assist device implantation) changed over time according to peak VO2 and VE/VCO2 slope and to major clinical and therapeutic variables. At 10 years, a progressively higher survival from group 1 to group 3 was observed, with no further improvement afterwards. A 20% risk for peak VO2 15 mL/min/kg (95% confidence interval 16-13), 9 (11-8), 4 (4-2) and 5 (7-4) was observed in group 1, 2, 3, and 4, respectively, while the VE/VCO2 slope value for a 20% risk was 32 (37-29), 47 (51-43), 59 (64-55), and 57 (63-52), respectively. CONCLUSIONS: Heart failure prognosis improved over time up to 2010 in a HF population followed by experienced centres. The peak VO2 and VE/VCO2 slope cut-offs identifying a definite risk progressively decreased and increased over time, respectively. The prognostic threshold of peak VO2 and VE/VCO2 slope must be updated whenever HF prognosis improves.

Dose-dependent efficacy of ß-blocker in patients with chronic heart failure and atrial fibrillation.

BACKGROUND: The usefulness of ß-blockers in heart failure (HF) patients with permanent atrial fibrillation (AF) has been questioned. METHODS AND RESULTS: We analyzed data from HF patients (958 patients (801 males, 84%, age 67 ±â€¯11 years)) with AF enrolled in the MECKI score database. We evaluated prognosis (composite of cardiovascular death, urgent heart transplant, or left ventricular assist device) of patients receiving ß-blockers (n = 777, 81%) vs. those not treated with ß-blockers (n = 181, 19%). We also analyzed the role ß1-selectivity and the role of daily ß-blocker dose. To account for different HF severity, Kaplan-Meier survival curves were normalized for relevant confounding factors and for treatment strategies. Dose was available in 629 patients. Median follow-up was 1312 (577-2304) days in the entire population, 1203 (614-2420) and 1325 (569-2300) days in patients not receiving and receiving ß-blockers. 224 (23%, 54/1000 events/year), 163 (21%, 79/1000 events/year), and 61 (34%, 49/1000 events/year) events were recorded, respectively. At 10-year patients treated with ß-blockers had a better outcome (HR 0.447, p < 0.01) with no effects as regards ß1selective drugs (53%) vs. ß1-ß2 blockers (47%). Survival improved in parallel with ß-blocker dose increase (HR 0.296, 0.496, 0.490 for the high, medium, and low dose vs. no ß-blockers, p < 0.0001). CONCLUSION: HF patients with AF taking a ß-blocker have a better outcome (with a survival improvement in parallel with daily dose but no differences as regards ß1 selectivity) but this does not mean that ß-blockers improve outcomes in these patients as we cannot control for all the potential confounders associated with ß-blocker use.

Multiparametric prognostic scores in chronic heart failure with reduced ejection fraction: a long-term comparison.

AIMS: Risk stratification in heart failure (HF) is crucial for clinical and therapeutic management. A multiparametric approach is the best method to stratify prognosis. In 2012, the Metabolic Exercise test data combined with Cardiac and Kidney Indexes (MECKI) score was proposed to assess the risk of cardiovascular mortality and urgent heart transplantation. The aim of the present study was to compare the prognostic accuracy of MECKI score to that of HF Survival Score (HFSS) and Seattle HF Model (SHFM) in a large, multicentre cohort of HF patients with reduced ejection fraction. METHODS AND RESULTS: We collected data on 6112 HF patients and compared the prognostic accuracy of MECKI score, HFSS, and SHFM at 2- and 4-year follow-up for the combined endpoint of cardiovascular death, urgent cardiac transplantation, or ventricular assist device implantation. Patients were followed up for a median of 3.67 years, and 931 cardiovascular deaths, 160 urgent heart transplantations, and 12 ventricular assist device implantations were recorded. At 2-year follow-up, the prognostic accuracy of MECKI score was significantly superior [area under the curve (AUC) 0.781] to that of SHFM (AUC 0.739) and HFSS (AUC 0.723), and this relationship was also confirmed at 4 years (AUC 0.764, 0.725, and 0.720, respectively). CONCLUSION: In this cohort, the prognostic accuracy of the MECKI score was superior to that of HFSS and SHFM at 2- and 4-year follow-up in HF patients in stable clinical condition. The MECKI score may be useful to improve resource allocation and patient outcome, but prospective evaluation is needed.

Prognostic role of ß-blocker selectivity and dosage regimens in heart failure patients. Insights from the MECKI score database.

AIMS: The use of ß-blockers represents a milestone in the treatment of heart failure with reduced ejection fraction (HFrEF). Few studies have compared ß-blockers in HFrEF, and there is little data on the effects of different doses. The present study aimed to investigate in a large database of HFrEF patients (MECKI score database) the association of ß-blocker treatment with a composite outcome of cardiovascular death, urgent heart transplantation or left ventricular assist device implantation, addressing the role of ß-selectivity and dosage regimens. METHODS AND RESULTS: In 5242 HFrEF patients, we investigated the role of: (i) ß-blocker treatment vs. non-ß-blocker treatment, (ii) ß1-/ß2-receptor-blockers vs. ß1-selective blockers, and (iii) daily ß-blocker dose. Patients were followed for 3.58 years, and 1101 events (18.3%) were observed; 4435 patients (86.8%) were on ß-blockers, while 807 (13.2%) were not. At 5 years, ß-blocker-patients showed a better outcome than non-ß-blocker-subjects [hazard ratio (HR) 0.48, P < 0.0001], while also considering potential confounders. A comparable prognosis was observed at 5 years in the ß1-/ß2-receptor-blocker (n = 2219) vs. ß1-selective group (n = 2216) (HR 0.95, P = ns). A better prognosis was observed in high-dose (>2 5 mg carvedilol equivalent daily dose, n = 1005) patients than in both medium dose (12.5-25 mg, n = 1431) and low dose (<12.5 mg, n = 1960) (HR 1.97, P < 0.001; HR 1.95, P = 0.001, respectively), with no differences between the last two groups (HR 0.84, P = ns). CONCLUSION: In a large population of chronic HFrEF patients, ß-blockers were associated with a more favourable prognosis without any difference between ß1- and ß2-receptor-blockers vs. ß1-selective blockers. A better outcome was observed in subjects receiving a high daily dose.

Heart failure and anemia: Effects on prognostic variables.

BACKGROUND: Anemia is frequent in heart failure (HF), and it is associated with higher mortality. The predictive power of established HF prognostic parameters in anemic HF patients is unknown. METHODS: Clinical, laboratory, echocardiographic and cardiopulmonary-exercise-test (CPET) data were analyzed in 3913 HF patients grouped according to hemoglobin (Hb) values. 248 (6%), 857 (22%), 2160 (55%) and 648 (17%) patients had very low (<11g/dL), low (11-12 for females, 11-13 for males), normal (12-15 for females, 13-15 for males) and high (>15) Hb, respectively. RESULTS: Median follow-up was 1363days (606-1883). CPETs were always performed safely. Hb was related to prognosis (Hazard ratio (HR)=0.864). No prognostic difference was observed between normal and high Hb groups. Peak oxygen consumption (VO2), ventilatory efficiency (VE/VCO2 slope), plasma sodium concentration, ejection fraction (LVEF), kidney function and Hb were independently related to prognosis in the entire population. Considering Hb groups separately, peakVO2 (very low Hb HR=0.549, low Hb HR=0.613, normal Hb HR=0.618, high Hb HR=0.542) and LVEF (very low Hb HR=0.49, low Hb HR=0.692, normal Hb HR=0.697, high Hb HR=0.694) maintained their prognostic roles. High VE/VCO2 slope was associated with poor prognosis only in patients with low and normal Hb. CONCLUSIONS: Anemic HF patients have a worse prognosis, but CPET can be safely performed. PeakVO2 and LVEF, but not VE/VCO2 slope, maintain their prognostic power also in HF patients with Hb<11g/dL, suggesting CPET use and a multiparametric approach in HF patients with low Hb. However, the prognostic effect of an anemia-oriented follow-up is unknown.

Sex Profile and Risk Assessment With Cardiopulmonary Exercise Testing in Heart Failure: Propensity Score Matching for Sex Selection Bias.

BACKGROUND: In heart failure (HF), women show better survival despite a comparatively low peak oxygen consumption (V˙o2): this raises doubt about the accuracy of risk assessment by cardiopulmonary exercise testing (CPET) in women. Accordingly, we aimed to check (1) whether the predictive role of well-known CPET risk indexes, ie, peak V˙o2 and ventilatory response (V˙e/V˙co2 slope), is sex independent and (2) if sex-related characteristics that impact outcome in HF should be considered as associations that may confound the effect of sex on survival. METHODS: The study population consisted of 2985 patients with HF, 498 (17%) of whom were women, from the multicentre Metabolic Exercise Test Data Combined with Cardiac and Kidney Indexes (MECKI): the end point was cardiovascular death within a 3-year period. RESULTS: During the follow-up, 305 (12%) men and 39 (8%) women (P = 0.005) died, and female sex was linked to better survival on univariate analysis (P = 0.008) and independent of peak V˙o2 and V˙e/V˙co2 slope on multivariate analysis. According to propensity score matching for female sex to exclude a sex selection bias and sample discrepancy, 498 men were selected: the standardized percentage bias ranged from 20.8 (P < 0.0001) to 3.3 (P = 0.667). After clinical profile harmonizing, female sex was predictive of HF at univariate analysis. CONCLUSIONS: The low peak V˙o2 and female association with better outcome in HF might be counterfeit: the female prognostic advantage is lost when sex-specific differences are correctly taken into account with propensity score matching, suggesting that for an effective and efficient HF model, adjustment must be made for sex-related characteristics.

The metabolic exercise test data combined with Cardiac And Kidney Indexes (MECKI) score and prognosis in heart failure. A validation study.

BACKGROUND: The Metabolic Exercise test data combined with Cardiac and Kidney Indexes (MECKI) score is a prognostic model to identify heart failure (HF) patients at risk for cardiovascular mortality (CVM) and urgent heart transplantation (uHT) based on 6 routine clinical parameters: hemoglobin, sodium, kidney function by the Modification of Diet in Renal Disease (MDRD) equation, left ventricle ejection fraction (LVEF), percentage of predicted peak oxygen consumption (VO2) and VE/VCO2 slope. OBJECTIVES: MECKI score must be generalizable to be considered useful: therefore, its performance was validated in a new sequence of HF patients. METHODS: Both the development (MECKI-D) and the validation (MECKI-V) cohorts were composed of consecutive HF patients with LVEF <40% able to perform a symptom-limited cardiopulmonary exercise testing. The CVM or uHT rates were analyzed at one, two and three years in both cohorts: all patients with a censoring time shorter than the scheduled follow-up were excluded, while those with events occurring after 1, 2 and 3 years were considered as censored. RESULTS: MECKI-D and MECKI-V consisted of 2009 and 992 patients, respectively. MECKI-V patients had a higher LVEF, higher peak VO2 and lower VE/VCO2 slope, higher prescription of beta-blockers and device therapy: after the 3-year follow-up, CVM or uHT occurred in 206 (18%) MECKI-D and 44 (13%) MECKI-V patients (p<0.000), respectively. MECKI-V AUC values at one, two and three years were 0.81 ± 0.04, 0.76 ± 0.04, and 0.80 ± 0.03, respectively, not significantly different from MECKI-D. CONCLUSIONS: MECKI score preserves its predictive ability in a HF population at a lower risk.

Renal function and peak exercise oxygen consumption in chronic heart failure with reduced left ventricular ejection fraction.

BACKGROUND: Chronic kidney disease is associated with sympathetic activation and muscle abnormalities, which may contribute to decreased exercise capacity. We investigated the correlation of renal function with peak exercise oxygen consumption (V̇O2) in heart failure (HF) patients. METHODS AND RESULTS: We recruited 2,938 systolic HF patients who underwent clinical, laboratory, echocardiographic and cardiopulmonary exercise testing. The patients were stratified according to estimated glomerular filtration rate (eGFR). Mean follow-up was 3.7 years. The primary outcome was a composite of cardiovascular death and urgent heart transplantation at 3 years. On multivariable regression, eGFR was predictor of peakV̇O2(P<0.0001). Other predictors were age, sex, body mass index, HF etiology, NYHA class, atrial fibrillation, resting heart rate, B-type natriuretic peptide, hemoglobin, and treatment. After adjusting for significant covariates, the hazard ratio for primary outcome associated with peakV̇O2<12 ml·kg(-1)·min(-1)was 1.75 (95% confidence interval (CI): 1.06-2.91; P=0.0292) in patients with eGFR ≥60, 1.77 (0.87-3.61; P=0.1141) in those with eGFR of 45-59, and 2.72 (1.01-7.37; P=0.0489) in those with eGFR <45 ml·min(-1)·1.73 m(-2). The area under the receiver-operating characteristic curve for peakV̇O2<12 ml·kg(-1)·min(-1)was 0.63 (95% CI: 0.54-0.71), 0.67 (0.56-0.78), and 0.57 (0.47-0.69), respectively. Testing for interaction was not significant. CONCLUSIONS: Renal dysfunction is correlated with peakV̇O2. A peakV̇O2cutoff of 12 ml·kg(-1)·min(-1)offers limited prognostic information in HF patients with more severely impaired renal function.

Deceptive meaning of oxygen uptake measured at the anaerobic threshold in patients with systolic heart failure and atrial fibrillation.

BACKGROUND: Oxygen uptake at the anaerobic threshold (VO2AT), a submaximal exercise-derived variable, independent of patients' motivation, is a marker of outcome in heart failure (HF). However, previous evidence of VO2AT values paradoxically higher in HF patients with permanent atrial fibrillation (AF) than in those with sinus rhythm (SR) raised uncertainties. DESIGN: We tested the prognostic role of VO2AT in a large cohort of systolic HF patients, focusing on possible differences between SR and AF. METHODS: Altogether 2976 HF patients (2578 with SR and 398 with AF) were prospectively followed. Besides a clinical examination, each patient underwent a maximal cardiopulmonary exercise test (CPET). RESULTS: The follow-up was analysed for up to 1500 days. Cardiovascular death or urgent cardiac transplantation occurred in 303 patients (250 (9.6%) patients with SR and 53 (13.3%) patients with AF, p = 0.023). In the entire population, multivariate analysis including peak oxygen uptake (VO2) showed a prognostic capacity (C-index) similar to that obtained including VO2AT (0.76 vs 0.72). Also, left ventricular ejection fraction, ventilation vs carbon dioxide production slope, ß-blocker and digoxin therapy proved to be significant prognostic indexes. The receiver-operating characteristic (ROC) curves analysis showed that the best predictive VO2AT cut-off for the SR group was 11.7 ml/kg/min, while it was 12.8 ml/kg/min for the AF group. CONCLUSIONS: VO2AT, a submaximal CPET-derived parameter, is reliable for long-term cardiovascular mortality prognostication in stable systolic HF. However, different VO2AT cut-off values between SR and AF HF patients should be adopted.

Surfactant-derived proteins as markers of alveolar membrane damage in heart failure.

BACKGROUND: In heart failure (HF) alveolar-capillary membrane is abnormal. Surfactant-derived proteins (SPs) and plasma receptor for advanced-glycation-end-products (RAGE) have been proposed as lung damage markers. METHODS: Eighty-nine chronic HF and 17 healthy subjects were evaluated by echocardiography, blood parameters, carbon monoxide lung diffusion (DLCO) and cardiopulmonary exercise test. We measured immature SP-B, mature SP-B, SP-A, SP-D and RAGE plasma levels. RESULTS: Immature SP-B (arbitrary units), mature SP-A (ng/ml) and SP-D (ng/ml), but not mature SP-B (ng/ml) and RAGE (pg/ml) levels, were higher in HF than in controls [immature SP-B: 15.6 (13.1, 75th-25th interquartile range) Vs. 11.1 (6.4), p<0.01; SP-A, 29.6 (20.1) Vs. 18.3 (13.5), p = 0.01; SP-D: 125 (90) Vs. 78 (58), p<0.01]. Immature SP-B, SP-A, SP-D and RAGE values were related to DLCO, peak oxygen consumption, ventilatory efficiency, and brain natriuretic peptide (BNP), whereas plasma mature SP-B was not. The DLCO Vs. immature SP-B correlation was the strongest one. At multivariate analysis, RAGE was associated to age and creatinine, SP-A to DLCO and BNP, SP-D to BNP, mature SP-B to DLCO and creatinine, and immature SP-B only but strongly to DLCO. CONCLUSIONS: Immature SP-B is the most reliable biological marker of alveolar-capillary membrane function in HF.

Prognostic value of indeterminable anaerobic threshold in heart failure.

BACKGROUND: In patients with heart failure (HF), during maximal cardiopulmonary exercise test, anaerobic threshold (AT) is not always identified. We evaluated whether this finding has a prognostic meaning. METHODS AND RESULTS: We recruited and prospectively followed up, in 14 dedicated HF units, 3058 patients with systolic (left ventricular ejection fraction <40%) HF in stable clinical conditions, New York Heart Association class I to III, who underwent clinical, laboratory, echocardiographic, and cardiopulmonary exercise test investigations at study enrollment. We excluded 921 patients who did not perform a maximal exercise, based on lack of achievement of anaerobic metabolism (peak respiratory quotient ≤1.05). Primary study end point was a composite of cardiovascular death and urgent cardiac transplant, and secondary end point was all-cause death. Median follow-up was 3.01 (1.39-4.98) years. AT was identified in 1935 out of 2137 patients (90.54%). At multivariable logistic analysis, failure in detecting AT resulted significantly in reduced peak oxygen uptake and higher metabolic exercise and cardiac and kidney index score value, a powerful prognostic composite HF index (P<0.001). At multivariable analysis, the following variables were significantly associated with primary study end point: peak oxygen uptake (% pred; P<0.001; hazard ratio [HR]=0.977; confidence interval [CI]=0.97-0.98), ventilatory efficiency slope (P=0.01; HR=1.02; CI=1.01-1.03), hemoglobin (P<0.05; HR=0.931; CI=0.87-1.00), left ventricular ejection fraction (P<0.001; HR=0.948; CI=0.94-0.96), renal function (modification of diet in renal disease; P<0.001; HR=0.990; CI=0.98-0.99), sodium (P<0.05; HR=0.967; CI=0.94-0.99), and AT nonidentification (P<0.05; HR=1.41; CI=1.06-1.89). Nonidentification of AT remained associated to prognosis also when compared with metabolic exercise and cardiac and kidney index score (P<0.01; HR=1.459; CI=1.09-1.10). Similar results were obtained for the secondary study end point. CONCLUSIONS: The inability to identify AT most often occurs in patients with severe HF, and it has an independent prognostic role in HF.