[Correlation between the Morris' index and pulmonary capillary pressure in patients with acute myocardial infarction]

The authors study the usefulness of the measurement of the negative area of P in V1 (Morris' index) in patients with acute myocardial infarction. The study was carried out prospectively in 70 patients, 31 of them having a Swan-Ganz catheter inserted permitting simultaneous hemodynamic and electrocardiographic measurements. No overall correlation was found between pulmonary capillary pressure (PCP) and Morris' index (Mlx), but a correlation existed in the subgroup of patients that showed evident variations of Mlx values during the study. On admission a relationship between PCP and Mlx was evident in 68% of the cases, without statistical significance. No PCP-Mlx correlation was found in the patients in whom the Mlx was always normal or abnormal during the study, nor in those with a prior history of arterial hypertension or left heart failure. An intraatrial conduction defect was found in 13% of the cases, no PCP-Mlx correlation being present in those. The fact that the PCP-Mlx correlation is best in patients with changing Mlx values in successive measurements that in patients with a prior history of hypertension or left ventricular failure suggests that Mlx values may vary with changes of left atrial pressure. The measurement of the Mlx to estimate left atrial pressure has little value in patients with conditions that may cause left atrial enlargement and intraatrial conduction defects.