The Right Ventricular Systolic Function Assessment in Adult Respiratory Distress Syndrome: Simple. Basic. Complex.

Abstract

To the Editor: We thank Dr. Dandel for his interest in our previously published article.1 We acknowledge that the pathogenicity of dominant SARS-COV-2 “variants of concern” during the second wave (Delta variant) may partially explain the higher mortality observed during the second wave. However, other factors, including steroid-resistant disease and changes in clinical management, should not be discarded.1 Dr. Dandel also suggested that right ventricular (RV) failure may be the primary cause of the high mortality rate of our ECMO patients observed during the second wave. Unfortunately, no precise and objective data supports this hypothesis in our series. However, we agree with Dr. Dandel on two essential points: First, we agree that in moderate-to-severe ARDS, the clinical impact of routinely monitoring RV systolic function with bedside echocardiography is obvious. An early diagnosis of RV systolic dysfunction to adapt medical management (ventilatory parameters, fluids, and vasopressors) is essential. However, choosing the most appropriate parameters to monitor RV systolic function is difficult. Classical parameters seem to have poor sensitivity to detect RV dysfunction2 and poor prognostic value.3 Using RV strain parameters to assess RV systolic function is promising, but the clinical significance for COVID-19-associated ARDS (C-ARDS) is still under debate.4 Nevertheless, advanced two-dimensional speckle tracking parameters, such as RV longitudinal shortening fraction (RV-LSF), seem more accurate. We recently reported in a cohort of 86 moderate-to-severe C-ARDS patients that RV dysfunction (defined by an RV-LSF < 20%) was frequent (43%) and was associated with 30-day mortality.5 Moreover, RV-LSF seems to be the most reliable parameter for assessing RV systolic function in patients with acute core pulmonale.6 The use of these parameters to choose the most appropriate support needs confirmation. Second, echocardiographic data before implementation and during ECMO therapy are, indeed, very useful. However, many factors (ultra-protective ventilation, prone positioning sessions, ventilator mode, pump/sweep gas flow...) can modify RV morphology and function under ECMO therapy. In this situation, distinguishing between RV adaptation and failure is difficult. That is why choosing relevant parameters to identify RV systolic dysfunction and the need for a standardized monitoring protocol are mandatory. Further studies are required to assess the feasibility, reproducibility, and clinical impact of the various RV parameters (conventional and advanced) that may be used during ECMO therapy. We agree that timely repeated ultrasound exams with heart/lung interaction evaluation are of utmost importance during the ECMO course.