Risk stratification in cardiomyopathy

Abstract

Prognostic stratification of cardiomyopathies represents a cornerstone for the appropriate management of patients and is focused mainly on arrhythmic events and heart failure. Cardiopulmonary exercise testing provides additional prognostic information, particularly in the setting of heart failure. Cardiopulmonary exercise testing data, integrated in scores such as the Metabolism Exercise Cardiac Kidney Index score have been shown to improve the risk stratification of these patients. Cardiopulmonary exercise testing has been analysed as a potential supplier of prognostic parameters in the context of hypertrophic cardiomyopathy, for which it has been shown that a reduced oxygen consumption peak, an increased ventilation/carbon dioxide production slope and chronotropic incompetence correlate with a worse prognosis. To a lesser extent, in dilated cardiomyopathy, it has been shown that the percentage of oxygen consumption peak, not the pure value, and the ventilation/carbon dioxide production slope are associated with a greater cardiovascular risk. Few data are available about other cardiomyopathies (arrhythmogenic and restrictive). Cardiomyopathy patients should be early and routinely referred to heart failure advanced centres in order to perform a comprehensive risk stratification which should include a cardiopulmonary exercise test, with variables and cut-offs shown to improve their risk stratification.

Keywords: CPET; Cardiomyopathy; MECKY score; exercise; prognosis; risk stratification.

Figure 1.

Parameters for the calculation of the metabolism exercise cardiac kidney index (MECKI) score: metabolic exercise (peak VO₂% pred, VE/VCO₂ slope), cardiac (LVEF), kidney (MDRD, ml/min), index. VO₂: oxygen consumption; LVEF: left ventricular ejection fraction; MDRD: Modification of Diet in Renal Disease study. VE: ventilation; VCO₂: carbon dioxide production.

Figure 2.

Survival free from cardiovascular death/heart transplantation in dilated cardiomyopathy (DCM) patients. Kaplan–Meier survival curves stratified by peak VO₂/kg (14–12 mL/kg/min refers to the classically used cut-points for peak VO₂, respectively, in the presence or absence of beta-blocker therapy, upper left panel), peak VO₂% cut-point 60%, upper right panel), VE/VCO₂ slope (cut-point 29, bottom left panel), combination of peak VO₂% (cut-point 60%) and VE/VCO₂ slope (cut-point 29, bottom right panel). D/HTx: cardiovascular death/heart transplantation; peak VO₂/kg: peak of oxygen consumption per kg; peak VO₂%: percentage of predicted oxygen consumption; VCO₂: carbon dioxide production; VE: ventilation. Reproduced from Sinagra et al., with permission.

Figure 3.

Relationships between oxygen pulse (VO₂/HR) versus heart rate (HR) in a patient with asymptomatic hypertrophic cardiomyopathy (HCM) (left column) and in a patient with New York Heart Association (NYHA II) mildly symptomatic HCM with end-stage phase (right column). Although different in magnitude, both patients showed a reduced VO₂ peak (70% and 55%), an early oxygen pulse flattening with a compensatory HR increase. Reproduced from Magrì and Santolamazza, with permission.