Characteristics of Left Ventricular Endocardial Electroanatomic Voltage Mapping in Patients With Tachycardia‐Induced Cardiomyopathy

INTRODUCTION: Tachycardia-induced cardiomyopathy (TICM) is a reversible cause of left ventricular (LV) systolic dysfunction. We evaluated LV endocardial electroanatomic mapping (EAM) to characterize electrical remodeling in TICM caused by atrial tachyarrhythmias. METHODS AND RESULTS: Patients undergoing radiofrequency catheter ablation of persistent atrial tachyarrhythmias were included. Detailed LV endocardial EAM was performed in 23 patients with LV dysfunction (LV ejection fraction [EF] < 40%) and 29 with normal LVEF (reference group). Electrogram voltage and the extent of voltage abnormalities were analyzed. Patients with LV dysfunction and normalized LVEF after ablation were diagnosed with TICM. Twenty-three patients met the TICM criteria. Compared to the reference group, TICM patients had a lower LV endocardial bipolar (median 2.7 mV [IQR 1.2-5.6 mV] vs. 3.9 mV [IQR 1.7-7.0 mV]; p < 0.01) and unipolar voltage (median 12.6 mV [IQR 9.1 - 16.3 mV] vs. 15.2 mV[IQR 12.0-20.1 mV]; p < 0.01) in both the global and regional LV. No extensive macroscopic scar, but small localized abnormal unipolar voltage areas (median 4.6 cm²) were found in most TICM patients, mainly in the basal inferolateral LV, and wall thinning was more common in those basal LV areas. A low bipolar voltage without abnormal potentials was found in most patients with TICM but was more diffusely distributed with multiple small areas (median 5.1 cm²). There was no significant difference in LV activation time between groups. CONCLUSION: Detailed LV endocardial EAM reveals diffuse voltage reduction and localized abnormal voltage areas in TICM, particularly in the basal inferolateral wall, even in the absence of persistent LV systolic dysfunction after maintenance of sinus rhythm.