Prolonged Circulatory Arrest is Not Associated with Stroke or Mortality after Pulmonary Thromboendarterectomy

Abstract

Purpose Patients with chronic thromboembolic pulmonary hypertension (CTEPH) frequently present with extensive distal clot burden, which adds complexity to pulmonary thromboendarterectomy (PTE). Complete endarterectomy often necessitates prolonged periods of hypothermic circulatory arrest (HCA), the ramifications of which are poorly understood. Objectives were to describe the association of HCA time with post-operative neurologic complications, operative mortality and other major morbidity after PTE. Methods From 2013 to 2019, 163 patients underwent PTE at a single academic institution. Median age was 51 [IQR 23] and 55% (N=89) were female. Operative approach involved profound hypothermia with multiple brief periods of HCA without aortic crossclamping. As event rates were low, the primary outcome was a composite of operative mortality, stroke, respiratory failure requiring tracheostomy and renal failure requiring dialysis. Both univariate and multivariable logistic regression analyses were performed to examine association between HCA and this composite outcome. Results Overall operative mortality was 6.8% (N=11), while 1% of patients (n=2) suffered stroke, 5% (n=8) required dialysis and 10% (n=17) required tracheostomy. In terms of hemodynamic outcomes, median improvement in mean PA pressures was 15mmHg [IQR 16] comparing pre-operative to last post-operative invasive monitoring. Median HCA time was 46 minutes [IQR 32] over a median of 3 [IQR 2] arrest periods at median core temperature of 17°C [IQR 2.2]. When grouped by HCA time less than or greater than 60 minutes, there was no significant difference in the composite outcome (15% versus 12%, p=0.720). Among nine patients with very prolonged HCA time greater than 90 minutes, the composite outcome occurred in one (11%). In a univariate logistic regression analysis, neither HCA time (OR 1.00, CI 0.99-1.01) nor number of arrests (OR 0.98, CI 0.94-1.02) were significant predictors of the composite. In a multivariable model, increasing age was the only significant predictor of the composite (OR 1.05, CI 1.01-1.10). Conclusion Prolonged HCA during PTE does not appear to confer increased risk of neurologic or other major complications. Therefore, more extensive endarterectomy should be pursued, when appropriate, to achieve the best hemodynamic outcome for patients with distal and bilateral disease.