An indirect method for evaluation of left ventricular function in acute myocardial infarction.

SUMMARY An indirect estimate of the contractility index, max LV dP/dt/LVEDP, has been examined in 32 patients following acute myocardial infarction (AMI) and in three patients with acute coronary insufficiency (ACI). The index was derived from arterial diastolic pressure (DP) obtained by sphygmomanometer, left ventricular filling pressure (LVFP) obtained by pulmonary artery balloon catheter, and pre-ejection period (PEP) determined from the phonocardiogram, carotid pulse, and ECG. These data were used in the relation (DP-LVFP)/PEP/LVFP (i.e., AP/At/LVFP) as an approximation of the direct contractility index max dP/dt/LVEDP. While measurements of PEP, DP, and LVFP used independently were not useful in distinguishing patients grouped in surviving ANII, nonsurviving AMI, and ACI categories, the AP/At/LVFP index showed marked separation of these groups. Because of the simplicity of measurement and minimal intravascular intervention, the index provides a safe and practical means of assessing the degree of left ventricular dysfulnction in patients with AMI. Additional Indexing Words: Left ventricular dP/dt Preejection period T HE MAXIMUM RATE of left ventricu-lar pressure rise (max dP/dt) is recognized as a sensitive indicator of cardiac performance.1-4 When this parameter is corrected for the effects of preload, its usefulness is increased. Reeves et al.1 were first to describe such a correction method by relating max dP/dt to left ventricular end-diastolic pressure (LVEDP), that is, dP/dt/LVEDP. Subsequently, this index has been refined by utilizing the ratio of max dP/dt to various other components of LV pressure.4 While these indices have shown potential value for evaluation of cardiac contractility, their application in acute myocardial infarction (AMI) has been limited because of the requirement of LV catheterization. The preejection period (PEP) has been used as an indirect means of estimating max dP/dt,5-8 but the dependence of PEP on aortic diastolic pressure (DP) and LV filling pressure (LVFP) limits its application in AMlI, where these pressures are often nlot ,vithin their normal ranges. Recently, a method for estimation of max dP/dt has beeni described which was found to correlate highly witlh the directly measured parameter in patienits vvith 291