Is It Time to Pay Attention to Right and Left Ventricular Apical Angles as Clinically Relevant Computed Tomography Measures in Acute Pulmonary Embolism?

Abstract

Background: In acute pulmonary embolism (PE), abrupt right ventricular (RV) pressure overload and ventricular interdependence are primary determinants of hemodynamic deterioration and short-term mortality. Conventional computed tomographic pulmonary angiography (CTPA) markers, such as the RV/left ventricular (LV) diameter ratio, exhibit variable prognostic performance and may not fully capture early geometric remodeling. It was hypothesized that CTPA-derived apical angle metrics, reflecting biventricular geometric distortion, provide complementary prognostic information beyond established clinical scores.

Methods: In this retrospective study of 535 consecutive patients with acute PE, novel CTPA-derived apical geometry metrics were evaluated: the RV apical angle (α1), the LV apical angle (α2), and their ratio (α1/ α2). The primary outcome was in-hospital mortality; long-term all-cause mortality served as the secondary outcome.

Results: Higher α1 and α1/α₂ values were significantly associated with greater pulmonary arterial obstruction, severe RV dysfunction, and higher clinical risk status. In-hospital mortality increased significantly across α1 tertiles (P = .017). In multiple logistic regression models, after adjustment for the Pulmonary Embolism Severity Index (PESI) score and the conventional RV/LV diameter ratio, both α1 and α1/α₂ remained independently associated with in-hospital mortality. Adding these apical metrics to the PESI-based baseline model significantly improved prognostic accuracy, demonstrating substantial incremental value for short-term risk stratification. Mortality risk increased linearly beyond thresholds of α1>32.5° and α1/α₂ > 1.17. In multiple Cox proportional hazards analysis, no imaging-derived parameter independently predicted long-term mortality.

Conclusions: Computed tomographic pulmonary angiography-derived apical angle metrics provide physiologically meaningful, continuous measures of acute RV geometric remodeling in acute PE. These metrics offer significant incremental prognostic value for in-hospital mortality beyond the PESI score and conventional CT markers.