Correlations Between the Chest Film and Hemodynamics in Acute Myocardial Infarction

Abstract

A series of 169 standardized chest films was analyzed relative to hemodynamic parameters obtained within 2 hr of the roentgenogram in 86 patients with acute myocardial infarction. The films were evaluated for cardiomegaly using the cardiothoracic ratio and the standardized, external left heart dimension. The radiographic appearance of the pulmonary vasculature was divided into levels of increasing severity: normal, pulmonary venous congestion, interstitial pulmonary edema, alveolar pulmonary edema. These were compared with wedge pressure levels of ⪕12, 13-18, 19-25, and >25 mm Hg, respectively. Correlations with the admission films of the 86 patients showed: 1) The appearance of the pulmonary vasculature accurately predicted the patient's wedge pressure on admission in 43% of the cases, overestimated it in 33% and underestimated it in 24%. 2) The presence of cardiomegaly and/or pleural effusion indicated an elevated wedge pressure with a high degree of certainty; however the absence of these signs did not exclude an elevated wedge pressure. 3) In only 62% of the studies was the chest film able to detect or exclude the presence of pulmonary venous hypertension. However, when wedge pressures were elevated to 19-25 mm Hg and over 25 mm Hg, 74% and 100%; respectively of roentgenograms had some evidence of pulmonary venous hypertension. 4) There was a high degree of correlation between the patient's admission physical findings, as evidenced by clinical classification, and the radiologic assessment of pulmonary venous hypertension. There was no statistical variation in the accuracy of the estimate of wedge pressure in relation to the time elapsed from onset of symptoms of myocardial infarction. However, a therapeutic phase lag was encountered in 21 patients, the chest films remaining abnormal for a period of 1 to 4 days following return of the wedge pressure to normal. A diagnostic phase lag was encountered in 6 patients in whom the chest film did not correlate with elevation of wedge pressure for up to 12 hr. Furthermore, in 17 patients the films were normal in spite of a persistently elevated wedge pressure for 6 to 24 hr. These studies document the limitations of the chest roentgenogram in predicting the hemodynamic status of patients with acute myocardial infarction.