The influence of occult right ventricular infarction on enzymatically estimated infarct size, hemodynamics and prognosis.

Clinical and hemodynamic manifestations of overt right ventricular infarction differ markedly from those that involve injury confined exclusively to the left ventricle. However, the frequency of covert right ventricular infarction and its influence on overall enzymatically estimated infarct size, hemodynamics and prognosis have not been characterized. Accordingly, 249 patients with transmural anterior or inferior left ventricular infarction were studied prospectively (average follow-up 20.7 months). Enzymatically estimated infarct size (average and frequency distribution) was similar among patients in both groups (25 ± 3.0 and 24 ± 1.8 CK-g-Eq/m2 [±ISEM]). Sixty-two patients were studied with invasive hemodynamic monitoring. Judging from the increased ratio of right ventricular end-diastolic pressure to pulmonary artery occlusive pressure in patients with inferior compared with anterior infarction (0.47 ± 0.7 vs 0–26 ± 0.3), and the greater fraction of patients who had a ratio greater than 0.45 (43% vs 14%), inferior infarction was frequently associated with occult right ventricular infarction. Although there were no significant differences in ventricular ectopic activity among patients in the two groups during the first 24 hours after the onset of infarction, early mortality was substantially less with inferior than with anterior infarction (12% vs 23%, p < 0.05), as was mortality throughout the first 2 years of follow-up (p < 0.01). Thus, covert right ventricular infarction, reflected by hemodynamic criteria, frequently contributes to overall enzymatic estimates of infarct size among patients with inferior transmural infarction, and accounts in part for the substantially increased initial and long-term survival compared with patients with anterior infarction associated with equivalent overall injury confined exclusively to the left ventricle.