ObjectiveNew York Heart Association (NYHA) functional class plays a central role in heart failure (HF) assessment but might be unreliable in mild presentations. We compared objective measures of HF functional evaluation between patients classified as NYHA I and II in the Rede Brasileira de Estudos em Insuficiência Cardíaca (ReBIC)-1 Trial.MethodsThe ReBIC-1 Trial included outpatients with stable HF with reduced ejection fraction. All patients had simultaneous protocol-defined assessment of NYHA class, 6 min walk test (6MWT), N-terminal pro-brain natriuretic peptide (NT-proBNP) levels and patient’s self-perception of dyspnoea using a Visual Analogue Scale (VAS, range 0–100).ResultsOf 188 included patients with HF, 122 (65%) were classified as NYHA I and 66 (35%) as NYHA II at baseline. Although NYHA class I patients had lower dyspnoea VAS Scores (median 16 (IQR, 4–30) for class I vs 27.5 (11–49) for class II, p=0.001), overlap between classes was substantial (density overlap=60%). A similar profile was observed for NT-proBNP levels (620 pg/mL (248–1333) vs 778 (421–1737), p=0.015; overlap=78%) and for 6MWT distance (400 m (330–466) vs 351 m (286–408), p=0.028; overlap=64%). Among NYHA class I patients, 19%–34% had one marker of HF severity (VAS Score >30 points, 6MWT <300 m or NT-proBNP levels >1000 pg/mL) and 6%–10% had two of them. Temporal change in functional class was not accompanied by variation on dyspnoea VAS (p=0.14).ConclusionsMost patients classified as NYHA classes I and II had similar self-perception of their limitation, objective physical capabilities and levels of natriuretic peptides. These results suggest the NYHA classification poorly discriminates patients with mild HF.

Background The New York Heart Association (NYHA) functional classification has evolved to become a major determinant of eligibility to medical interventions and clinical trials, but its reliability to discriminate patients with mild heart failure (HF) has been questioned by studies that demonstrated a major overlap in self-reported symptoms and laboratory markers between NYHA classes I and II. Purpose To assess the reliability of NYHA classification by comparing cardio-pulmonary exercise test (CPET) results and its overlap between HF patients classified as NYHA I and II. Methods We retrospectively analyzed data from HF patients who underwent CPET in 3 medical centers in Brazil. NYHA class was defined as recorded on CPET day or during the previous clinical visit. Inclusion criteria were diagnosis of HF, age ≥16, and NYHA class I or II. We analyzed overlap between kernel density estimations for the percent-predicted peak VO2, minute ventilation/carbon dioxide production (VE/VCO2) slope, and oxygen uptake efficiency slope (OUES) in patients in NYHA classes I and II. Categorical variables were compared using chi-square tests. Results We included 684 patients, of which 42% (284) were classified as NYHA I. Mean age was 56.1 years; 44% (303) were female and mean left ventricular ejection fraction was 36% (±14.2%). Regarding CPET measures, mean global percent-predicted peak VO2 was 56.6% (±26.1%), VE/VCO2 slope was 38.8 (±10.2), and OUES was 1.50 (±0.59). Kernel density overlap between NYHA classes I and II was considerable: 83% for percent-predicted peak VO2, 89% for VE/VCO2 slope, and 85% for OUES (Figure 1). There was no significant difference between NHYA I and II in CPET indicators of poor prognosis: percent-predicted peak VO2 &lt;50% was present in 53% vs. 48% of patients classified as NYHA I and II, respectively (p=0.15); VE/VCO2 slope &gt;36 in 54% vs. 57% (p=0.39); and OUES &lt;1.4 in 46% vs. 48% (p=0.51). Conclusions HF patients classified as NYHA I and II overlap substantially in objective measures of functional capacity assessed by CPET. These findings suggest that NYHA classification is a poor discriminator of cardiopulmonary capacity among patients with mild HF, and raise questions about its use as a benchmark to guide HF therapy. FUNDunding Acknowledgement Type of funding sources: None. Figure 1

AimsIn this multicentre study, we compared cardio-pulmonary exercise test (CPET) parameters between heart failure (HF) patients classified as New York Heart Association (NYHA) class I and II to assess NYHA performance and prognostic role in mild HF. Methods and resultsWe included consecutive HF patients in NYHA class I or II who underwent CPET in three Brazilian centres. We analysed the overlap between kernel density estimations for the per cent-predicted peak oxygen consumption (VO 2 ), minute ventilation/carbon dioxide production (VE/VCO 2 ) slope, and oxygen uptake efficiency slope (OUES) by NYHA class. Area under the receiver-operating characteristic curve (AUC) was used to assess the capacity of per cent-predicted peak VO 2 to discriminate between NYHA class I and II. For prognostication, time to all-cause death was used to produce Kaplan-Meier estimates. Of 688 patients included in this study, 42% were classified as NYHA I and 58% as NYHA II, 55% were men, and mean age was 56 years. Median global per cent-predicted peak VO 2 was 66.8% (IQR 56-80), VE/VCO 2 slope was 36.9 (31.6-43.3), and mean OUES was 1.51 (±0.59). Kernel density overlap between NYHA class I and II was 86% for per cent-predicted peak VO 2 , 89% for VE/VCO 2 slope, and 84% for OUES. Receiving-operating curve analysis showed a significant, albeit limited performance of per cent-predicted peak VO 2 alone to discriminate between NYHA class I vs. II (AUC 0.55, 95% CI 0.51-0.59, P = 0.005). Model accuracy for probability of being classified as NYHA class I (vs. NYHA class II) across the spectrum of the per cent-predicted peak VO 2 was limited, with an absolute probability increment of 13% when per cent-predicted peak VO 2 increased from 50% to 100%. Overall mortality in NYHA class I and II was not significantly different (P = 0.41), whereas NYHA class III patients displayed a distinctively higher death rate (P < 0.001). Conclusions Patients with chronic HF classified as NYHA I overlapped substantially with those classified as NYHA II in objective physiological measures and prognosis. NYHA classification may represent a poor discriminator of cardiopulmonary capacity in patients with mild HF.