Peak oxygen uptake in relation to total heart volume discriminates heart failure patients from healthy volunteers and athletes.

Henrik Engblom,Torsten Buhre,Björn Ekmehag,Katarina Steding,Bo Hedén,Henrik Mosén,Håkan Arheden,Marcus Carlsson

doi:10.1186/1532-429x-12-74

Abstract

BackgroundAn early sign of heart failure (HF) is a decreased cardiac reserve or inability to adequately increase cardiac output during exercise. Under normal circumstances maximal cardiac output is closely related to peak oxygen uptake (VO2peak) which has previously been shown to be closely related to total heart volume (THV). Thus, the aim of this study was to derive a VO2peak/THV ratio and to test the hypothesis that this ratio can be used to distinguish patients with HF from healthy volunteers and endurance athletes. Thirty-one patients with HF of different etiologies were retrospectively included and 131 control subjects (60 healthy volunteers and 71 athletes) were prospectively enrolled. Peak oxygen uptake was determined by maximal exercise test and THV was determined by cardiovascular magnetic resonance. The VO2peak/THV ratio was then derived and tested.ResultsPeak oxygen uptake was strongly correlated to THV (r2 = 0.74, p < 0.001) in the control subjects, but not for the patients (r2 = 0.0002, p = 0.95). The VO2peak/THV ratio differed significantly between control subjects and patients, even in patients with normal ejection fraction and after normalizing for hemoglobin levels (p < 0.001). In a multivariate analysis the VO2peak/THV ratio was the only independent predictor of presence of HF (p < 0.001).ConclusionsThe VO2peak/THV ratio can be used to distinguish patients with clinically diagnosed HF from healthy volunteers and athletes, even in patients with preserved systolic left ventricular function and after normalizing for hemoglobin levels.

Highlights

Heart failure (HF) is a complex syndrome associated with a variety of etiologies and clinical presentations [1] which implies a major diagnostic challenge
Hemoglobin level was assessed within 2 weeks of the exercise test in patients and on the day of the exercise test in healthy volunteers and athletes who gave their consent for blood sampling
Even though a significant difference in LV ejection fraction (LVEF) was found between the control subjects and the heart failure (HF) patients (p < 0.001; Figure 3A), there was a significant overlap with 29% (9/31) of the HF patient examinations showing LVEF > 50%

Summary

Introduction

Heart failure (HF) is a complex syndrome associated with a variety of etiologies and clinical presentations [1] which implies a major diagnostic challenge. ACC/AHA have identified 4 stages (A-D) with emphasis on the evolution and progression of HF, where stage A defines patients who are at high risk for developing HF but has no structural disorder of the heart and no signs or Cardiac performance can be assessed by maximal exercise testing with measurements of respiratory gas exchange to determine peak oxygen uptake (VO2peak), shown to be closely correlated to maximal cardiac output [5,6]. This method is predominantly used in evaluation of patients with established HF under consideration for heart transplantation [7,8]. In a multivariate analysis the VO2peak/THV ratio was the only independent predictor of presence of HF (p < 0.001)

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