Prognostic importance of right ventricular dysfunction.

When considering the entire range of left ventricular ejection fractions (LVEF) after a myocardial infarction, this parameter is a powerful predictor of mortality. However extended follow up studies have shown that prolonged survival occurs in some patients with congestive heart failure (CHF) who have adverse conventional prognostic markers, including very low LVEF. In patients with LVEF < 20%, the absolute value has little prognostic significance but peak oxygen consumption (peak V~O2) is predictive. There is increasing evidence that right ventricular ejection fraction (RVEF) is also a powerful predictor of mortality in this subgroup of patients—perhaps the most powerful predictor. In patients with CHF caused by dilated cardiomyopathy (DCM), reduced RVEF assessed using gated heart pool scanning (< 38%) has been shown to be associated with increased mortality in patients with LVEF < 30% but not in those patients with higher LVEFs. Similarly, in patients with ischaemic heart disease (IHD), RVEF is prognostically important in those patients with LVEF < 40%. In a study undertaken in a cardiac transplant waiting list population (of mixed aetiology), patients were stratified according to RVEF greater or less than 24%. RVEF was shown to be an independent predictor of survival in a multivariate model that included LVEF. One year survival in the two groups was 44% and 93%, respectively. Juilliere and colleagues confirmed that LVEF and RVEF were both independent predictors of survival in a multivariate model. In another study of patients with mean (SD) LVEF 22 (7)%, resting RVEF (> 35%) was shown to be the most powerful independent predictor of survival in a multivariate model which included the other conventional prognostic markers (LVEF, peak V~O2, peak percentage age and sex adjusted V~O2, left ventricular end diastolic volume index, left ventricular end systolic volume index, and cardiac index). The presence of right ventricular involvement also has a major effect on short term outcome in patients with acute inferior myocardial infarction (odds ratio for in hospital mortality 3.2). Successful primary angioplasty promptly normalises RVEF in this setting and is associated with improved in-hospital mortality compared with patients in whom primary angioplasty is unsuccessful (2% v 58%). DETERMINANTS OF RVEF IN PATIENTS WITH CHF RVEF is determined by intrinsic right ventricular contractile function, and by right ventricular preload and afterload. Because DCM generally affects both ventricles, RVEF tends to be lower for any given LVEF in patients with DCM versus those with IHD. It is important to note that the function of the left ventricle can influence that of the right ventricle in two important ways. Firstly, the interventricular septum is shared by both ventricles, and contributes substantially to right ventricular contractile function. Secondly, RVEF is influenced by the afterload against which it has to eject (total pulmonary resistance), which is also greatly affected by left ventricular end diastolic pressure (LVEDP) as well as by pulmonary vascular resistance. Therefore RVEF was negatively associated with raised mean pulmonary artery pressure and with raised right ventricular end diastolic pressure (RVEDP), with the combination being additive in predicting RVEF. For these reasons, in patients with acute anterior myocardial infarction, in whom the infarct is limited to the anterior wall of the left ventricle and the upper septum, right ventricular ejection fraction is depressed at day 2, but recovers by day 10 despite persistent impairment of LVEF.