• cardiopulmonary exercise testing
• Heart failure
• peak cardiac power output-to-left ventricular mass

ABSTRACT

Background. Peak cardiac power output (peak CPO) at exercise echocardiography showed to be closely related to peak VO2 at cardiopulmonary exercise testing (CPET). To gain further perspective in the evaluation of left ventricular (LV) remodeling in myocardial hypertrophy, the peak cardiac power output-to-LV mass (peak CPOM), a measure of the rate at which cardiac work is delivered with respect to the potential energy stored in LV mass, was recently introduced.
Aim. To compare the value of peak CPOM with CPET variables in the prognostic stratification of patients with chronic stable heart failure (HF) due to LV dysfunction.
Materials and methods. 115 patients with chronic stable HF (mean LV EF% 0.31±0.6) underwent CPET and exercise echocardiography. The two tests were performed within 7 days according to standard symptom-limited exercise protocols. Peak CPOM was calculated as the product of a constant (K=2.22 x 10-1) with cardiac output (CO) and the mean arterial pressure (MAP) divided by LV mass (M) to convert the units to watts/100 g: CPO = K x CO (l/min) x MAP (mmHg) x M-1(g). Patients were followed-up for the composite end point of all-cause mortality or hospitalization for HF.
Results. There were 16 deaths and 21 hospitalizations for worsening HF during a mean follow-up of 24 months. At ROC analyses, the areas under the curve for the composite end point were greater for peak CPOM (AUC=0.82) and VE/VCO2 (AUC=0.76), followed by CPO (AUC=0.75), peakVO2 predicted (AUC 0.72), VO2 (AUC =0.69), LV EF (AUC=0.69) and NYHA class (AUC=0.68). At the multivariate logistic regression analysis, peak CPOM was the most powerful predictor of outcome (p <0.0001). The Kaplan-Meier analysis revealed that survival free from HF-hospitalization at 24 months was 83% in patients with a peak CPOM >0.60 watts/100 g, while it was 29% in those with a peak CPOM ≤0.60 watts/100 g (p <0.0001, Logrank: 34.1).
Conclusion. The assessment of LV ratio power-to-mass by the echo-derived peak CPOM can provide additional insights in the prognostic stratification of patients with HF.