The pulmonary artery pulsatility index identifies severe right ventricular dysfunction in acute inferior myocardial infarction.

BACKGROUND

Right ventricular dysfunction (RVD) is a major cause of morbidity and mortality in the setting of acute inferior wall myocardial infarction (IWMI), and early detection may improve clinical outcomes. We defined a novel hemodynamic index, the pulmonary artery pulsatility index (PAPi), and explored whether the PAPi correlates with severe RVD in acute IWMI.

METHODS

From 2008 to 2010, we identified 20 patients presenting with angiographically confirmed proximal right coronary artery occlusion and suspected RVD (sRVD) as defined by hemodynamic instability, profound bradycardia, or ST-elevation in lead V4R. Two controls groups were studied (1) 50 patients with nonobstructive coronary artery disease (Non-CAD) and (2) 14 patients presenting with acute coronary syndrome requiring left coronary stenting (ACS). Hemodynamic indices analyzed at the time of catheterization included: (1) the right atrial to pulmonary capillary wedge pressure ratio (RA:PCWP), (2) right ventricular stroke work (RVSW), and (3) the PAPi. Qualitative echocardiographic scores of RV systolic function were determined by two blinded investigators within 24 hr of catheterization.

RESULTS

Among subjects with sRVD, 7 (35%) received a percutaneous RV support device (pRVSD) for medically refractory RV failure and 4 (20%) died prior to hospital discharge. Compared to Non-CAD and ACS controls, subjects with sRVD had a significantly lower PAPi (4.32 ± 3.04 vs. 5.52 ± 4.40 vs. 1.11 ± 0.57, respectively, P < 0.01) and a higher RA:PCWP ratio (0.48 ± 0.24 vs. 0.51 ± 0.26 vs. 0.81 ± 0.30, respectively, P < 0.05). Both the PAPi and RA:PCWP ratios correlated significantly with RVSW and qualitative echocardiographic grading. The PAPi demonstrated the highest sensitivity (88.9%) and specificity (98.3%) for predicting in-hospital mortality and/or requirement of a pRVSD. Using ROC curve derived cut-points, a PAPi ≤ 0.9 provided 100.0% sensitivity and 98.3% specificity (C-statistic: 0.998) for predicting these outcomes, exceeding the predictive value of the RA:PCWP ratio or RVSW.

CONCLUSIONS

The PAPi is a simple, invasive hemodynamic measure that may help identify high-risk patients with acute IWMI with severe RVD. Earlier identification of this high-risk population may improve clinical outcomes.