Postoperative PAPi: Grading Our Post-LVAD Management

To the Editor – Right ventricular failure (RVF) is a dreaded complication of durable left ventricular assist device (LVAD) therapy as it causes significant morbidity and mortality. It can be seen in 9-42% of patients following device activation. 1 Thus, identifying cases of subclinical RVF early in the postoperative course is crucial in promptly initiating RVF mitigating strategies. Pulmonary artery pulsatility index (PAPi) has previously been demonstrated to provide real-time quantification of right ventricular (RV) systolic performance and has further demonstrated utility in risk-stratifying LVAD recipients for RVF. 2 However, data on PAPi use for detecting RVF after LVAD initiation is limited. In this issue of the Journal, Wei et al. presented a single-center retrospective analysis of 67 durable LVAD recipients, who had PAPi measured hourly for up to 48 hours postoperatively to examine whether the average PAPi acquired during this time predicted RVF following LVAD implantation. 3 30% of the patients developed RVF, and these patients had a lower median postoperative PAPi than those who did not (1.31 vs 1.82, p=0.01). 3 The authors also constructed a receiver operator curve and identified 1.56 as the optimal cutoff for postoperative PAPi with a sensitivity of 0.70 and specificity of 0.68. 3 We applaud the authors for furthering the evidence on PAPi as a valuable tool in the LVAD population, which until now has focused on its role in preoperative risk stratification for RVF. While postoperative PAPi by its very nature cannot retrospectively inform pre-LVAD risk of RVF, it does have potential value in prognosticating RV performance post-LVAD. This can improve outcomes in those previously deemed low risk for developing RVF by steering rapid treatment with inotropes, inhaled pulmonary vasodilators, or mechanical circulatory support in those patients with low postoperative PAPi. Interestingly, the authors found no correlation between preoperative and postoperative PAPi. More puzzling is that the preoperative PAPi of the patients who developed RVF was higher than those who did not develop RVF (2.35 vs 2.14), which is inconsistent with the >30 studies examining preoperative PAPi as a predictor of RVF after LVAD implantation. 4 Our group published a meta-analysis of these studies and determined a preoperative PAPi <2.17 was predictive of RVF after LVAD implantation. 4 PAPi is a dynamic parameter and is dependent on changes to patients’ clinical states or medical therapy, so it is logical that a “normal” PAPi maybe lower postoperatively given the effects of general anesthesia, physiological stress of surgery, dynamic fluid shifts, active inotrope/vasopressor therapy, and LVAD pump speed settings. The study by Gudejko et al., which was not included in our meta-analysis, demonstrated that PAPi obtained intraoperatively immediately after chest closure as low as 1.5 was not associated with RVF. 5 This illustrates that postoperative PAPi must be interpreted in the context of many variables composing a patient's clinical status at a given time. We would also caution against viewing postoperative PAPi as a risk stratification tool like the Michigan and EUROMACS scores or even preoperative PAPi. One of the goals of identifying patients at increased risk for RVF is to guide LVAD candidacy and preoperative optimization of a patient's clinical status. To improve outcomes, patients at high risk for RVF should not have an LVAD implanted in the first place. However, we may be poorly managing low-risk patients by administering excessive fluids, hypoventilating them, providing inadequate inotropic support, or utilizing high pump speeds, resulting in RV deformation and dysfunction. In this regard, there may be great value in tracking PAPi postoperatively to correlate RV function with postoperative management. The authors’ discovery may have an important role in post-LVAD patient care, but these findings need to be validated with larger prospective studies. 1Turner KR. Right Ventricular Failure After Left Ventricular Assist Device Placement—The Beginning of the End or Just Another Challenge? J Cardiothorac Vasc Anesth. 2019;33:1105-1121.2Kang G, Ha R, Banerjee D. Pulmonary artery pulsatility index predicts right ventricular failure after left ventricular assist device implantation. J Heart Lung Transplant. 2016;35:67-73.3Wei J, Franke J, Kee A, Dukes R, Leonardo V, Flynn BC. Postoperative Pulmonary Artery Pulsatility Index Improves Prediction of Right Ventricular Failure after Left Ventricular Assist Device Implantation. J Cardiothorac Vasc Anesth. 2023. In press.4Essandoh M, Kumar N, Hussain N, et al. Pulmonary artery pulsatility index as a predictor of right ventricular failure in left ventricular assist device recipients: A systematic review. J Heart Lung Transplant. Aug 2022;41:1114-1123.5Gudejko MD, Gebhardt BR, Zahedi F, et al. Intraoperative hemodynamic and echocardiographic measurements associated with severe right ventricular failure after left ventricular assist device implantation. Anesth Analg. 2019;128:25-32. The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper.