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Ventricular pacing site separation by cardiac computed tomography: validation for the prediction of clinical response
S Modi1, Raymond Yee1, David Scholl2
1Division of Cardiology, Schulich School of Medicine & Dentistry, London, Canada.
Insights
Cardiac Resynchronization Therapy (CRT) response can be predicted by measuring inter-lead distance (ILD) using cardiac CT. Circumferential ILD shows strong predictive accuracy for CRT success, aiding in patient selection.
Area of Science:
- Cardiology
- Medical Imaging
- Biomedical Engineering
Background:
- Cardiac Resynchronization Therapy (CRT) is a treatment for heart failure that benefits only two-thirds of patients.
- Optimizing lead placement, specifically maximizing the distance between ventricular pacing sites, may improve CRT outcomes.
- Cardiac computed tomography (CT) offers a novel approach to quantify 3D inter-lead distance (ILD) for predicting CRT response.
Purpose of the Study:
- To investigate the association between cardiac CT-derived ILD measures and echocardiographic response to CRT.
- To determine if standardized ILD measurements can predict clinical success following CRT implantation.
Main Methods:
- Forty-two patients receiving CRT underwent post-procedural cardiac-gated CT scans.
- Direct and circumferential (myocardial) ILD were measured from CT images by blinded observers.
- Clinical response was defined as a ≥15% reduction in left ventricular end-systolic volume (LVESV) at 6 months via echocardiography.
Main Results:
- A significant clinical response to CRT occurred in 83% of patients (35/42).
- Both direct and circumferential ILD measures were associated with CRT response in univariate analysis.
- Circumferential ILD demonstrated the highest predictive accuracy (AUC 0.78) for CRT response, with excellent inter- and intra-observer reproducibility.
Conclusions:
- Cardiac CT-derived circumferential ILD is a predictive marker for clinical response to CRT.
- Integrating these CT-based ILD measures into pre-procedural planning may optimize pacing site selection and improve CRT therapeutic benefit.
- Further research is warranted to validate these findings and their clinical utility.
Abstract:
Cardiac Resynchronization Therapy (CRT) fails to provide benefit in up to one-third of patients. Maximizing the geographic separation of right and left ventricular pacing lead sites has been suggested as one way to improve response. Cardiac CT provides an opportunity to explore 3-dimensional inter-lead distance (ILD) measures for the prediction of CRT response. The objective of this study was to investigate associations between standardized measures of ILD by cardiac CT and echocardiographic response to CRT. Forty-two consecutive patients undergoing CRT had serial clinical and echocardiographic evaluations performed in addition to a post-procedural cardiac-gated CT with blinded measurement of direct and circumferential (via the myocardium) ILD measures. Clinical response to CRT, the primary clinical outcome, was defined as a ≥15% reduction in LVESV using echocardiography at 6-months. The mean age and ejection fraction was 63.6 ± 8.9 years and 25.2 ± 7.8%, respectively. The primary outcome occurred in 35 of 42 patients (83%). Both direct and circumferential CT-based ILD measures were associated with the primary outcome by univariate analysis. Receiver Operator Characteristic analysis identified Circumferential ILD to have the strongest predictive accuracy (AUC 0.78). Inter- and intra-observer reproducibility of CT-derived ILD measures was excellent. Circumferential ILD measures on cardiac CT are predictive of clinical response to CRT. Incorporation of these measures into the selection of optimal pacing targets, particularly from pre-procedural CT coronary vein imaging may be of therapeutic benefit and warrants further investigation.