PATHOPHYSIOLOGY AND NATURAL HISTORY RIGHT VENTRICULAR INFARCTION Hemodynamically important right ventricular infarction: follow-up evaluation of right ventricular systolic function at rest and during exercise with radionuclide ventriculography and respiratory gas exchange

The prognosis and recovery of right ventricular systolic function in patients with hemodynamically documented right ventricular myocardial infarction (RVMI) is unclear. Therefore 27 patients who met hemodynamic criteria for RVMI were followed for at least 1 year. Four patients died within 1 year and 23 survived. Postmortem examination performed in three of the four patients showed extensive infarction of the right and left ventricles. Survivors underwent early and late follow-up resting radionuclide ventriculograms and late exercise studies. During long-term follow-up (1 to 4 years) resting radionuclide ventriculography demonstrated a significant improvement in right ventricular ejection fraction (30 + 7% to 43 8%; p < .001) and right ventricular wall motion index (2.2 0.4 to 1.5 ± 0.5; p < .001) in 18 patients who survived longer than 1 year. Fourteen of these patients underwent upright bicycle exercise while off /3-blocking drugs and peak radionuclide ejection fraction was acquired after anaerobic threshold was achieved. Right ventricular ejection fraction increased significantly from 41 ± 10% to 47 + 12% (p < .001), as did the left ventricular ejection fraction (55 + 15% to 60 ± 12%; p < .05). The direction and magnitude of change of the right ventricular ejection fraction correlated significantly with the left ventricular ejection fraction (r = .82, p < .02). Deviations from this correlation occurred in patients who had a decreased, forced expiratory volume in 1 sec and an abnormal ventilatory reserve during exercise. Also, the onset of anaerobic threshold during exercise correlated with the peak exercise right ventricular ejection fraction (r = .82, p < .02). However, there was no significant correlation with the left ventricular ejection fraction. Therefore we conclude that patients with RVMI and significant left ventricular dysfunction have a poor 1 year prognosis. Otherwise, the long-term prognosis of patients who present with hemodynamically important RVMI is excellent. Furthermore, in the recovery phase, right ventricular ejection fraction increases and right ventricular functional reserve is preserved during exercise in patients not limited by angina, pulmonary disease, or left ventricular failure. Circulation 75, No. 5, 996-1003, 1987. THE IDENTIFICATION of right ventricular myocardial infarction (RVMI) varies depending on the diagnostic technique used. ` However, only hemodynamic findings have been validated against necropsy-proven From the Division of Cardiology, Department of Medicine, University of Texas Health Science Center, San Antonio. Supported in part by NIH New Investigator Research Award R23 HL27508 and Research Training Grant T32 HL07350 from the NHLBI, by the Veterans Administration, and by the American Heart Association, Texas Affiliate. Address for correspondence: Louis J. Dell'Italia, M.D., Department of Medicine/Cardiology, University of Texas Health Science Center, 7703 Floyd Curl Dr., San Antonio, TX 78284. Received Oct. 16, 1986; revision accepted Feb. 12. 1987. right ventricular necrosis, thereby establishing hemodynamic criteria as the most accurate markers of RVMI.9 In numerous noninvasive studies, radionuclide ventriculographic` or two-dimensional echocardiographic`7 evidence of right ventricular enlargement or decreased systolic performance has been reported to occur in 40% to 50% of patients with acute inferior myocardial infarction (IMI). In contrast, we showed that only 20% of 53 consecutive patients with acute IMI had hemodynamic findings characteristic of RVMI even after a volume challenge. Because of this discrepancy in the diagnosis of RVMI, its shortand CIRCULATION 996 by gest on July 5, 2017 http://ciajournals.org/ D ow nladed from PATHOPHYSIOLOGY AND NATURAL HISTORY-RIGHT VENTRICULAR INFARCTION long-term prognosis has been controversial. We5 and others9' 10 have noted that patients who present with hemodynamically important RVMI have a poor shortterm prognosis, whereas Haines et al.` have reported that patients with radionuclide ventriculographic evidence of RVMI have an excellent long-term survival. In addition, other investigators have reported a marked improvement in right ventricular systolic performance in the recovery phase.4' 12 However, these studies 4, 11, 12 did not use hemodynamic criteria for the early diagnosis of RVMI and therefore may have included patients with decreased right ventricular systolic performance secondary to other causes such as chronic obstructive pulmonary disease, left ventricular dysfunction, or transient right ventricular ischemia rather than infarction. To date no study has provided long-term followup data on patients presenting with hemodynamically important RVMI. Previously, we reported that hemodynamic and radionuclide ventriculographic evidence of significant left ventricular dysfunction along with persistent precordial ST segment depression were predictors of death in patients 1 year after acute IMI. 3 Therefore we attempted to determine whether these same markers applied to the 13 patients with hemodynamic evidence ofRVMI from the previous cohort'3 and to an additional 14 patients with hemodynamically documented acute RVMI whom we studied to determine the relative efficacy of dobutamine compared with nitroprusside therapy.14 Also, follow-up studies were perforned in these patients who met strict criteria for acute RVMI by both hemodynamics and radionuclide ventriculography to evaluate right ventricular systolic function and to determine the functional reserve of the right ventricle by means of rest and exercise radionuclide ventriculography and respiratory gas exchange analysis.