Detailed analysis of tachycardia cycle length aids diagnosis of the mechanism and location of atrial tachycardias.

AIMS: Although the mechanism of an atrial tachycardia (AT) can usually be elucidated using modern high-resolution mapping systems, it would be helpful if the AT mechanism and circuit could be predicted before initiating mapping. OBJECTIVE: We examined if the information gathered from the cycle length (CL) of the tachycardia can help predict the AT-mechanism and its localization. METHODS: One hundred and thirty-eight activation maps of ATs including eight focal-ATs, 94 macroreentrant-ATs, and 36 localized-ATs in 95 patients were retrospectively reviewed. Maximal CL (MCL) and minimal CL (mCL) over a minute period were measured via a decapolar catheter in the coronary sinus. CL-variation and beat-by-beat CL-alternation were examined. Additionally, the CL-respiration correlation was analysed by the RhythmiaTM system. : Both MCL and mCL were significantly shorter in macroreentrant-ATs [MCL = 288 (253-348) ms, P = 0.0001; mCL = 283 (243-341) ms, P = 0.0012], and also shorter in localized-ATs [MCL = 314 (261-349) ms, P = 0.0016; mCL = 295 (248-340) ms, P = 0.0047] compared to focal-ATs [MCL = 506 (421-555) ms, mCL = 427 (347-508) ms]. An absolute CL-variation (MCL-mCL) < 24 ms significantly differentiated re-entrant ATs from focal-ATs with a sensitivity = 96.9%, specificity = 100%, positive predictive value (PPV) = 100%, and negative predictive value (NPV) = 66.7%. The beat-by-beat CL-alternation was observed in 10/138 (7.2%), all of which showed the re-entrant mechanism, meaning that beat-by-beat CL-alternation was the strong sign of re-entrant mechanism (PPV = 100%). Although the CL-respiration correlation was observed in 28/138 (20.3%) of ATs, this was predominantly in right-atrium (RA)-ATs (24/41, 85.7%), rather than left atrium (LA)-ATs (4/97, 4.1%). A positive CL-respiration correlation highly predicted RA-ATs (PPV = 85.7%), and negative CL-respiration correlation probably suggested LA-ATs (NPV = 84.5%). CONCLUSION: Detailed analysis of the tachycardia CL helps predict the AT-mechanism and the active AT chamber before an initial mapping.

Confirmation of the achievement of linear lesions using "activation vectors" based on omnipolar technology.

BACKGROUND: Although differential pacing conventionally has been used to confirm the achievement of block across linear lesion sets, high-resolution mapping demonstrates that pseudo-block is observed in 20%-30% of cases. OBJECTIVES: The purpose of this study was to examine the reliability and versatility of a method using "activation vectors" based on omnipolar technology to confirm the block line. METHODS: Linear ablation was performed during pacing, with the HD Grid catheter (Abbott) placed beside the linear lesion opposite the pacing site. The endpoint of complete linear lesion was complete inversion of the activation vectors to the opposite direction. When inversion of the activation vectors was not observed after 10 minutes of radiofrequency (RF) application, high-resolution mapping was performed to assess whether complete block was achieved. RESULTS: In 33 patients, 24 cavotricuspid isthmus lines, 11 mitral isthmus (MI) lines, 16 posterior lines, and 2 intercaval lines were performed using this method. Of the total of 53 lines, 10 (18.9%) required intermediate evaluation of the block line with high-resolution mapping because of the absence of inversion of activation vectors despite 10 minutes of RF application, resulting in incomplete block with endocardial gaps or epicardial conductions. Additional RF applications finally achieved inversion in direction of activation vectors in the 10 lines. In total, the present method can diagnose achievement of complete block line with 100% accuracy, whereas conventional differential pacing misdiagnosed incomplete block with epicardial conduction in posterior lines in 3 cases and in MI lines in 2 cases. CONCLUSION: Confirmation of complete linear lesions using "activation vectors" based on omnipolar technology is a reliable and versatile method.

Differences in the electrophysiological findings of repeat ablation between patients who first underwent cryoballoon ablation and radiofrequency catheter ablation for paroxysmal atrial fibrillation.

INTRODUCTION: Several studies have revealed that second-generation cryoballoon (CB)-based pulmonary vein (PV) isolation is noninferior to radiofrequency (RF)-based PV isolation for patients with drug-refractory paroxysmal atrial fibrillation (AF). However, electrophysiological differences in repeat ablation remain unclear. METHODS AND RESULTS: This study examined electrophysiological differences during the repeat ablation between patients who first underwent RF catheter ablation and CB ablation; PV durability and non-PV AF foci were assessed for these patients. We enrolled 919 and 491 patients who underwent CB ablation (CB group) and RF catheter ablation (RF group), respectively, for paroxysmal AF between January 2013 and June 2017 at our institution. PV isolation using RF ablation involved the left atrium (LA) antrum and part of the LA posterior wall. After 2 years of follow-up, 62 and 80 patients in the CB and RF groups, respectively, underwent repeat ablation. PV reconnections were more frequent in the RF group than in the CB group (left superior PV: 46.2% and 14.5%, P < .001; left inferior PV: 35.0% and 11.2%, P = .001; right superior PV: 40.0% and 22.6%, P = .031; right inferior PV: 36.2% and 19.4%, P = .039; PVs: 39.8% and 16.9%, P < .001). LA AF foci were more frequent in the CB group than in the RF group (27.4% and 7.5%; P = .002). Other non-PV foci were prevalent in both groups. CONCLUSION: Fewer LA-PV reconnections occurred with CB ablation. However, extensive PV isolation may eliminate many LA AF foci.