Sanfilippo et al . raise two important concerns pertaining to our article in JASE . In our study, we found that the ratio of right ventricular to left ventricular end-diastolic diameter, right ventricular systolic pressure, tricuspid annular plane systolic excursion, and inferior vena cava (IVC) collapsibility were associated with mortality in patients with acute pulmonary embolism who presented to the intensive care unit (ICU). Of the 211 patients included in the study, 19 (9%) received intravenous thrombolytic therapy, and 55 (26%) required mechanical ventilation.

The first issue raised by Sanfilippo et al . is whether the use of thrombolytic therapy affected our results. We adjusted the Cox regression analysis by age, gender, and the use of thrombolytic therapy. The variables left ventricular end-diastolic diameter (hazard ratio per centimeter, 0.54; 95% confidence interval [CI], 0.38–0.77), tricuspid annular plane systolic excursion (hazard ratio per centimeter, 0.56; 95% CI, 0.32–0.99), and left ventricular ejection fraction (hazard ratio per 10%, 0.75; 95% CI, 0.60–0.95) remained significant predictors of lower long-term mortality adjusted by age and gender. Similarly, we obtained the same echocardiographic predictors of ICU and hospital mortality when we added the variable use of thrombolytic therapy to our analyses. A distinct analysis of the subgroup of patients who received thrombolytic was not performed given the limited number of patients that received this therapy.

The second concern is whether the predictive ability of IVC collapsibility ≥50% for ICU and hospital mortality was affected by the use of mechanical ventilation. The use of mechanical ventilation was significantly associated with ICU (odds ratio [OR], 12.0; 95% CI, 4.6–32.3) and hospital (OR, 11.9; 95% CI, 5.3–27.0) mortality, when adjusted by Acute Physiology and Chronic Health Evaluation (APACHE) IV and Pulmonary Embolism Severity Index (PESI) scores, respectively. IVC collapsibility ≥50% remained a significant predictor of ICU mortality (OR, 0.26; 95% CI, 0.08–0.84) when adjusted by APACHE IV score and the use of mechanical ventilation. Similarly, IVC collapsibility ≥50% persisted as a significant predictor of hospital mortality (OR, 0.31; 95% CI, 0.11–0.88) when adjusted by PESI score and the use of mechanical ventilation. In the subgroup of patients who did not require mechanical ventilation, IVC collapsibility ≥50% remained a significant predictor of ICU mortality (OR, 0.09; 95% CI, 0.01–0.93) when adjusted by APACHE IV score. Likewise, IVC collapsibility ≥50% remained a significant predictor of hospital mortality (OR, 0.18; 95% CI, 0.03–0.99) when adjusted by PESI score. Conversely, in the subset of patients who required mechanical ventilation, IVC collapsibility ≥50% was no longer a significant predictor of ICU (OR, 0.45; 95% CI, 0.10–2.11) or hospital mortality (OR, 0.45; 95% CI, 0.12–1.69), when adjusted by APACHE IV or PESI score, respectively.

In addition, Sanfilippo et al . asked whether we could identify predictors of right ventricular recovery after acute pulmonary embolism. We believe this would be a great follow-up study for us or other investigators to perform. Unfortunately, we did not collect data on follow-up echocardiography for this particular study. Furthermore, because it was a retrospective cohort study, data on follow-up echocardiography were very limited, and follow-up echocardiography was not performed at established intervals. Future prospective investigations in which echocardiograms are obtained at predetermined intervals according to established protocols are needed to answer this important question.

In summary, adjusting for the use of thrombolytic therapy did not affect our results. Nevertheless, caution should be taken when applying our results to patients with acute pulmonary emboli who received thrombolytic therapy, given that a small percentage of patients received this treatment in our cohort. IVC collapsibility ≥50% was a predictor of ICU or hospital mortality only in spontaneously breathing patients with acute pulmonary embolism.