Assessment of right ventricular function in acute inferior myocardial infarction using 133-xenon imaging

The detection of right ventricular dysfunction in acute inferior myocardial infarction is important because of its potentially serious consequences which may be remediable with the appropriate therapeutic manoeuvres. A technique has been developed to assess right ventricular function using 133-xenon. This technique was applied to 26 patients who had sustained an acute inferior myocardial infarction. Right ventricular ejection fractions ranged from 7-54%, mean 30 +/- 11%, which was significantly lower than values obtained from normal volunteers (n = 21), mean 43 +/- 5%, and patients with arteriographically proven coronary artery disease without previous myocardial infarction (n = 12), mean 39 +/- 9%, P less than 0.001, and P less than 0.001, respectively. In the patients with acute inferior myocardial infarction 18 patients (69%) had evidence of right ventricular dysfunction (right ventricular ejection fraction less than 35%). 13/26 patients (50%) had clinical evidence of right ventricular dysfunction with a mean right ventricular ejection fraction 26 +/- 11% (range 7-54%) which was significantly lower than the patients without evidence of right ventricular dysfunction, mean 35 +/- 9% (range 16-49%), P less than 0.001. The clinical signs had a sensitivity of 72% (13/18), a specificity of 87.5% (7/8) and a predictive accuracy of 76% (20/26) when compared to the imaging data.

(1) gated 133-xenon imaging provides a method for assessing right ventricular function in the setting of acute myocardial infarction; (2) a wide spectrum of right ventricular dysfunction occurs following inferior myocardial infarction which may not manifest itself clinically.