Peak exercise responses in heart failure: back to basics

Abstract

Evaluating central haemodynamics became a prominent cardiological feature in the 1950s following Sarnoff and Berglund's introduction of Starling's Law into practice via a family of ventricular function curves,1 but it went out of favour after 1981 when Benge2 and Franciosa3 claimed discrepancy between haemodynamics and exercise capacity in heart failure (HF) patients. Dismissing its value became fashionable in subsequent decades with further emphasis of its dissociation with changes in symptoms. In 1991, Mancini and colleagues4 greatly contributed to the widespread use of cardiopulmonary exercise testing (CPX) by showing its prognostic value in patients with severe HF referred for transplantation. Since this landmark study, a large number of studies have confirmed the unsurpassed prognostic value of peak exercise capacity, generally reported as peak oxygen consumption (peak VO2/kg), in HF patients. The simple explanation for this is that, according to the Fick principle, peak exercise VO2 is determined by peak exercise cardiac output and arteriovenous oxygen difference. When Chomsky et al. 5 tried to reintroduce the usefulness of haemodynamic evaluation in selecting transplant candidates in 1996, they were rather overwhelmed by counter arguments.6,7 The emergence of such discrepancies is clearly puzzling, especially in view of the fact that central haemodynamics offer by far the best means of looking into cardiac performance and dysfunction. There are a number of reasons why haemodynamic evaluations went out of favour. Chief amongst these are the choice of unrepresentative haemodynamic variables and the misplaced belief that measurements at rest can be representative of actual cardiac function irrespective of reserve capacity. Such a misconception probably stemmed from the misleadingly title of the 1981 paper by Franciosa,3 which also failed to highlight that in their own study, exercise haemodynamics actually correlated very well with exercise capacity. A more … *Corresponding author. Tel: +33 1 4995 6608, Fax: +33 1 4995 8439, Hopital Lariboisiere, Assistance Publique, 2 rue Ambroise Pare, 75010 Paris, France. Email: alain.cohen-solal{at}lrb.aphp.fr.