19-02: Electrocardiographic Mapping Vector Predicts Acute Response to Cardiac Resynchronization Therapy

Introduction: Biventricular depolarization times derived from high-resolution electrocardiographic mapping (ECM) can be used to calculate a vector which expresses both magnitude and direction of electrical dyssynchrony in 3D. We investigated whether this ECM vector could predict acute response in CRT candidates.

Methods: 57 systolic heart failure patients with QRS duration >120ms were included (30 LBBB, 3 RBBB and 24 non-specific conduction delay). Electrical activation maps were derived using ECM in spontaneous rhythm. The cartesian coordinates of >2000 virtual electrodes were multiplied by their depolarization times and then summed to create the ECM vector. The ECM vector amplitude was used as a measure of biventricular dyssynchrony. An increase in invasive LV dP/dtmax of >10% during CRT was defined as acute response.

Results: The ECM vector accurately predicted acute CRT response (area under the receiver operating characteristic curve [AUC] 0.94, optimal threshold 115 ms, sensitivity and specificity 91%) outperforming QRS duration (AUC 0.82, threshold 160 ms, sensitivity 64% both p < 0.05 versus ECM vector and specificity 89%) and LBBB morphology (sensitivity 91%, P = NS, specificity 71%, p < 0.05 versus ECM vector). Figure shows ECM maps of two patients with LBBB and similar QRS width. Left panel shows a ECM vector (105 ms) below threshold with poor acute response (LV dPdtmax +6%) while right panel shows a larger ECM vector (141 ms) with good acute response (LV dPdtmax +22%).

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Conclusion: The ECM vector accurately predicts acute CRT response and could be a useful non-invasive prognostic tool to help select patients for CRT.