Paced P-wave morphology templates to guide atrial tachycardia localization: A derivation and validation study.

BACKGROUND: Surface ECG is a useful tool to guide mapping of focal atrial tachycardia (AT). OBJECTIVES: We aimed to construct 12-lead ECG templates for P-wave morphology (PWM) during endocardial pacing from different sites in both atria in patients with no apparent structural heart disease (derivation cohort), with the goal of creating a localization algorithm, which could subsequently be validated in a cohort of patients undergoing catheter ablation of focal AT (validation cohort). METHODS: We prospectively enrolled consecutive patients who underwent electrophysiology study, had no structural heart disease and no atrial enlargement. Atrial pacing, at twice diastolic threshold, was carried out at different anatomical sites in both atria. Paced PWM and duration were assessed. An algorithm was generated from the constructed templates of each pacing site. The algorithm was applied on a retrospective series of successfully ablated AT patients. Overall and site-specific accuracy were determined. RESULTS: Derivation cohort included 65 patients (25 men, age 37 ± 13 years). Atrial pacing was performed in 1025 sites in 61 patients (95%) in RA and in 15 patients (23%) in LA. The validation cohort included 71 patients (28 men, age 52 ± 19 years). AT were right atrial in 66.2%. The algorithm successfully predicted AT origin in 91.5% of patients (100% in LA and 87.2% in RA). It was off by one adjacent segment in the remaining 8.5%. CONCLUSIONS: A simple ECG algorithm based on paced PWM templates was highly accurate in localizing site of origin of focal AT in patients with structurally normal hearts.

Anteroseptal basal right ventricular entrainment is simple and superior to apical entrainment in identifying mechanism of supraventricular tachycardia.

BACKGROUND: Differentiation between atrioventricular nodal reentry tachycardia (AVNRT) and atrioventricular reentrant tachycardia (AVRT) can be sometimes challenging. Apical right ventricular (RV) entrainment can help in differentiation; however, it has some fallacies. We thought to compare the accuracy of anteroseptal basal RV entrainment to RV apical entrainment in identifying the mechanism of supraventricular tachycardia (SVT). METHODS: Forty-two consecutive patients with SVT who underwent catheter ablation were prospectively studied. Apical RV entrainment was performed initially followed by basal entrainment from the anteroseptal basal RV avoiding His or atrial capture. Postpacing interval (PPI), PPI-tachycardia cycle length (TCL), corrected PPI-TCL, and stimulus-atrial minus ventricular-atrial (VA) intervals were measured. RESULTS: Entrainment was achieved from both sites of RV in 34 patients (ten men; mean age 42 ± 15 years), 20 with typical AVNRT, 1 with atypical AVNRT, and 13 with AVRT (eight left sided, four right sided, and one septal accessory pathways). PPI-TCL, corrected PPI (cPPI)-TCL, and stimulus-atrial-VA intervals were significantly longer with basal entrainment in AVNRT (171 ± 30 vs. 153 ± 22 ms (p = 0.003), 148 ± 21 vs. 131 ± 20 ms (p = 0.002), and 145 ± 17 vs. 136 ± 15 ms (p = 0.005), respectively). Receiver-operating characteristic curves showed higher AUC for the above parameters with basal entrainment compared to apical entrainment. Cutoff values of basal PPI-TCL of >110 ms and cPPI-TCL of >95 ms had better sensitivities (100 % for both vs. 95 and 90 %, respectively, for apical values) and specificities (85 and 92 % vs. 77 and 92 %, respectively) for diagnosis of AVNRT. CONCLUSION: Basal RV entrainment from the anteroseptal basal RV is a simple maneuver that is superior to apical ventricular entrainment in identifying the mechanism of SVT.