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QRS-Corrected Prediction of the Diastolic Rest Period for Coronary CT Angiography in Patients with Complete Left

Tsubasa Morioka1, Shingo Kato2, Kouta Mitsutake1

  • 1Department of Radiology, Yokohama City University Hospital, Yokohama 236-0004, Japan.

Journal of Cardiovascular Development and Disease
|June 25, 2026
PubMed

Insights

A QRS-corrected formula accurately predicts the slow-filling phase in coronary computed tomography angiography for patients with complete left bundle branch block. This simple adjustment improves diagnostic accuracy by accounting for QRS prolongation.

Area of Science:

  • Cardiology
  • Radiology
  • Medical Imaging

Background:

  • Optimal phase selection in coronary computed tomography angiography (CCTA) is critical for accurate diagnosis.
  • The conventional formula for predicting the mid-diastolic slow-filling (SF) phase is based on heart rate and atrioventricular conduction time.
  • The validity of this formula in complete left bundle branch block (CLBBB), characterized by significant QRS prolongation and mechanical dyssynchrony, is uncertain.

Purpose of the Study:

  • To evaluate the impact of bundle branch block on cardiac-phase selection in CCTA.
  • To validate a QRS-corrected predictive model for the SF phase in patients with CLBBB.

Main Methods:

  • Retrospective analysis of 94 patients: sinus rhythm (n=40), complete right bundle branch block (CRBBB, n=36), and CLBBB (n=18).
  • Comparison of measured SF at the proximal right coronary artery with predictions from the conventional formula (SF = -362 + 0.742 × [RR - PQ]).
  • Evaluation of a proposed QRS-corrected formula incorporating a "-(QRS - 100)" subtraction and regression analyses exclusively for the CLBBB cohort.

Main Results:

  • The conventional formula significantly overestimated SF in CLBBB patients (average 37.9 ms, RMSE 42.5 ms).
  • Regression models for the CLBBB group showed similar coefficients to the conventional formula, indicating preserved physiological dependency on RR and PQ intervals.
  • The proposed QRS-corrected formula minimized overestimation bias (mean error -6.9 ms, p=0.176) and achieved higher predictive accuracy (RMSE 21.2 ms).

Conclusions:

  • A novel predictive regression model is not necessary for CLBBB patients.
  • Incorporating a theoretical subtraction for pathological QRS prolongation optimally corrects the diastolic resting phase selection.
  • The QRS-corrected formula provides a simple yet effective method for accurate SF phase prediction in CLBBB patients undergoing CCTA.
Abstract

Keywords:
QRS durationbundle branch blockcardiac phasecoronary CT angiographyleft bundle branch blockslow filling

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