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OBJECTIVE: In patients with valvular heart disease, chronically elevated left atrial and pulmonary pressures may lead to right ventricular strain and ultimately right heart failure. Elevated pulmonary artery (PAP) and left ventricular end diastolic (LVEDP) pressures have been used as markers of right heart dysfunction and correlate with poor outcomes. Using cardiac MRI (cMRI), it is possible to directly quantify both left and right ventricular function (LVEF and RVEF), and here we compare cMRI to traditional markers as outcome predictors.
METHODS: A retrospective review of prospectively collected data was performed for all patients undergoing valve surgery from January 2004-February 2008 at a single center (n=103). All patients underwent preoperative cardiac catheterization, with 56 additionally receiving cMRI. Patients were divided into two cohorts, those receiving cMRI, and those receiving only catheterization. Demographics were compared between groups and found to be similar. Univariate and multivariate logistic regression models were applied to determine predictors of mortality. Finally, predictive models for mortality using preoperative PAP, mean PAP (MPAPA), and LVEDP were compared to models using LVEF and RVEF obtained from cMRI.
RESULTS: Overall, the two groups were generally similar. Average cMRI LVEF and RVEF were 57% and 46%, respectively. Of the risk factors analyzed, only age emerged as an isolated predictor of mortality (p=0.01) within the univariate models. Step-wise regression models were created using the catheterization or cMRI data. When compared, the cMRI model has a slightly better R^2, c (prediction accuracy), and sensitivity/specificity (0.22 v 0.28; 0.77 v 0.82; and 0.63/0.62 v 0.69/0.64, respectively).
CONCLUSIONS: In patients presenting for cardiac surgery, cMRI can accurately assess left and right heart function and morphology. Within our population, LVEF and RVEF were generally maintained and served as better predictors of mortality than traditional PAP values. Additionally, cMRI allows stratification of elevated PAPs into those caused by right heart dysfunction, and those due to other causes (such as OSA), allowing these other causes to be addressed preoperatively.