Evaluation of left ventricular systolic function revisited in septic shock

Abstract

The meta-analysis of Huang and coworkers failed to find any evidence for a protective effect of a decreased left ventricular (LV) ejection fraction (EF). These results have to be interpreted with caution since in most studies included in the meta-analysis patients with LV systolic dysfunction received inotropic drugs. We have some arguments suggesting that such a treatment may improve macrocirculation and microcirculation and finally prognosis. This paper allows us to clarify the meaning of LV function in septic shock patients. In all experimental models of septic shock using the load-independent parameter of LV systolic function, LV contractility impairment, called septic cardiomyopathy, has been reported to be constant. However, LVEF reflects the coupling between LV contractility and LV afterload. A normal LVEF may be observed when the arterial tone is severely depressed, as in septic shock, despite seriously impaired intrinsic LV contractility. LV systolic function, evaluated using an echocardiograph or another device, is then more a reflection of arterial tone (and its correction) than of intrinsic LV contractility. As a consequence, the incidence of LV systolic dysfunction greatly depends on the time of the evaluation, reflecting the fact that, during resuscitation and treatment, vasoplegia and then LV afterload are corrected, thus unmasking septic cardiomyopathy. With these points in mind, we can revisit the results of Margaret Parker's original study: it is not that the patients with a low EF survived better, but rather that the other patients had an increased mortality due to persistent profound vasoplegia.

Figure 1

Incidence of left ventricular systolic dysfunction according to the time of the evaluation. H6, H12, H24, H72, the time (hours) between admission and echocardiographic evaluation [4,15,17,18].