Hisaki Makimoto

Augmented ST-Segment Elevation During Recovery From Exercise Predicts Cardiac Events in Patients With Brugada Syndrome

OBJECTIVESnThe goal of this study was to evaluate the prevalence and the clinical significance of ST-segment elevation during recovery from exercise testing.nnnBACKGROUNDnDuring recovery from exercise testing, ST-segment elevation is reported in some patients with Brugada syndrome (BrS).nnnMETHODSnTreadmill exercise testing was conducted for 93 patients (91 men), 46 ± 14 years of age, with BrS (22 documented ventricular fibrillation, 35 syncope alone, and 36 asymptomatic); and for 102 healthy control subjects (97 men), 46 ± 17 years of age. Patients were routinely followed up. The clinical end point was defined as the occurrence of sudden cardiac death, ventricular fibrillation, or sustained ventricular tachyarrhythmia.nnnRESULTSnAugmentation of ST-segment elevation ≥0.05 mV in V(1) to V(3) leads compared with baseline was observed at early recovery (1 to 4 min at recovery) in 34 BrS patients (37% [group 1]), but was not observed in the remaining 59 BrS patients (63% [group 2]) or in the 102 control subjects. During 76 ± 38 months of follow-up, ventricular fibrillation occurred more frequently in group 1 (15 of 34, 44%) than in group 2 (10 of 59, 17%; p = 0.004). Multivariate Cox regression analysis showed that in addition to previous episodes of ventricular fibrillation (p = 0.005), augmentation of ST-segment elevation at early recovery was a significant and independent predictor for cardiac events (p = 0.007), especially among patients with history of syncope alone (6 of 12 [50%] in group 1 vs. 3 of 23 [13%] in group 2) and among asymptomatic patients (3 of 15 [20%] in group 1 vs. 0 of 21 [0%] in group 2).nnnCONCLUSIONSnAugmentation of ST-segment elevation during recovery from exercise testing was specific in patients with BrS, and can be a predictor of poor prognosis, especially for patients with syncope alone and for asymptomatic patients.

Increased incidence of esophageal thermal lesions using the second-generation 28-mm cryoballoon.

Background—Pulmonary vein isolation is an established treatment option for atrial fibrillation. To date, the incidence and quality of ablation-induced esophageal thermal lesions (ETLs) using the recently introduced second-generation cryoballoon (CB, ArcticFront Advance, Medtronic) is unknown. Methods and Results—In patients with drug-refractory paroxysmal atrial fibrillation or short-standing persistent atrial fibrillation, pulmonary vein (PV) isolation was performed using the second-generation CB. The endoluminal esophageal temperature was monitored via a temperature probe. After PV isolation, esophagogastroduodenoscopy (EGD) was performed to assess the incidence of ETLs. In 50 patients (18 women; age, 61±11 years; left atrial diameter, 43±5 mm), successful CB-based PV isolation was performed. Lowest median balloon temperature and esophageal temperature for the right superior PV were −51°C and 35.8°C, −47°C and 35°C for the right inferior PV, −51°C and 34.4°C for the left superior PV, −48°C and 34.6°C for the left inferior PV, and −54°C and 34.5°C for the left common PV, respectively. EGD performed 2±1 days post ablation demonstrated superficial thermal lesions and thermal ulcerations in 1 of 50 (2%) and 5 of 50 (10%) patients, respectively. In patients with ETLs, during ≥1 freeze cycle the endoluminal esophageal temperature measured <3.0°C. All thermal lesions were in the healing process on repeat EGD 4±2 days after initial endoscopy. Conclusions—Using the second-generation 28-mm CB, ETLs were detected in 6 of 50 (12%) patients. All ETLs were in the healing process on repeat EGD. An esophageal temperature safety cutoff may prove valuable in the prevention of ETLs and requires further evaluation.

Unexpectedly High Incidence of Stroke and Left Atrial Appendage Thrombus Formation After Electrical Isolation of the Left Atrial Appendage for the Treatment of Atrial Tachyarrhythmias

Background—Electric left atrial appendage (LAA) isolation (LAAI) may occur during catheter ablation of atrial tachyarrhythmias. Data regarding the risk of thromboembolic events and stroke after LAAI are sparse. This study evaluated the incidence of LAA thrombus formation and thromboembolic events after LAAI. Methods and Results—Fifty patients had LAAI (age=71 years; female=56%; CHA2DS2-VASc score before ablation =3 [2;3]). LAAI patients were compared with matched patients with comparable baseline characteristics who underwent atrial fibrillation ablation without LAAI (n=50). Ablation strategies in the LAAI group included pulmonary vein isolation in 50 (100%), left atrial isthmus line in 47 (94%), anterior line in 45 (90%), complex atrial fractionated potentials in 24 (48%), and roofline in 14 (28%) patients. Transesophageal echocardiography was performed during follow-up in 47/50 (94%) patients in the LAAI group and in all patients of the control group. Oral anticoagulation (OAC) independent of CHA2DS2-VASc score was strongly recommended in all patients. During a median follow-up of 6.5 (4–12) months, stroke occurred in 2 patients on OAC and transient ischemic attack in one without OAC in the LAAI group. In the remaining 47 patients, LAA thrombus was identified on transesophageal echocardiography in 10 (21%) patients (OAC=9; no OAC=1). In the control group, no LAA thrombus was detected and no stroke occurred (P<0.001). Stable sinus rhythm was maintained in 32 patients (64%) of the LAAI group after a median follow-up of 6.5 months (4–12), including 17/32 patients on antiarrhythmic drugs. Conclusions—After LAAI, an unexpectedly high incidence of LAA thrombus formation and stroke was observed despite OAC therapy.

Clinical impact of the number of extrastimuli in programmed electrical stimulation in patients with Brugada type 1 electrocardiogram

BACKGROUNDnUse of programmed electrical stimulation (PES) for risk stratification of Brugada syndrome (BrS) is controversial.nnnOBJECTIVEnTo elucidate the role of the number of extrastimuli during PES in patients with BrS.nnnMETHODSnConsecutive 108 patients with type 1 electrocardiogram (104 men, mean age 46 ± 12 years; 26 with ventricular fibrillation [VF], 40 with syncope, and 42 asymptomatic) underwent PES with a maximum of 3 extrastimuli from the right ventricular apex and the right ventricular outflow tract. Ventricular arrhythmia (VA) was defined as VF or nonsustained polymorphic ventricular tachycardia >15 beats. Patients with VA induced by a single extrastimulus or double extrastimuli were assigned to group SD (Single/Double), by triple extrastimuli to group T (Triple), and the remaining patients to group N.nnnRESULTSnVA was induced in 81 patients (VF in 71 and polymorphic ventricular tachycardia in 10), in 4 by a single extrastimulus, in 41 by double extrastimuli, and in 36 by triple extrastimuli. During 79 ± 48 months of follow-up, 24 patients had VF events. Although the overall inducibility of VA was not associated with an increased risk of VF (log-rank P = .78), group SD had worse prognosis than did group T (P = .004). Kaplan-Meier analysis in patients without prior VF also showed that group SD had poorer outcome than did group T and group N (P = .001). Positive and negative predictive values of VA induction with up to 2 extrastimuli were, respectively, 36% and 87%, better than those with up to 3 (23% and 81%, respectively).nnnCONCLUSIONSnThe number of extrastimuli that induced VA served as a prognostic indicator for patients with Brugada type 1 electrocardiogram. Single extrastimulus or double extrastimuli were adequate for PES of patients with BrS.

In vivo left-ventricular contact force analysis: comparison of antegrade transseptal with retrograde transaortic mapping strategies and correlation of impedance and electrical amplitude with contact force

Aims Clinical outcomes following radiofrequency ablation of ventricular tachycardias (VTs) depend on catheter tip-to-tissue contact force (CF). Left-ventricular (LV) mapping is performed via antegrade-transseptal or retrograde-transaortic approaches, and the applied CF may depend on the approach used. This study evaluated (i) the impact of antegrade-transseptal vs. retrograde-transaortic LV-mapping approaches on CF and catheter stability and (ii) the clinical value of the commonly used surrogate markers of catheter–myocardial contact—impedance, unipolar, and bipolar electrogram amplitudes. Methods and results An antegrade-transseptal and a retrograde-transaortic LV-mapping approach was performed in 10 patients undergoing VT ablation by using CF-sensing catheters. Operators were blinded to CF data and data were analysed according to 11 predefined LV segments. Three thousand three hundred and twenty-four mapping points (1577 antegrade, 1747 retrograde) were analysed, including 80 (2.4%) points with maximum CF > 100 g. Median antegrade and retrograde CF were 16.0 g (q1–q3; 8.4–26.2) and 15.3 g (9.8–23.4), respectively. Contact force was significantly higher antegradely in mid-anteroseptum, mid-lateral, and apical segments, and significantly higher retrogradely in basal-anteroseptum, basal-inferoseptum, basal-inferior, and basal-lateral segments. Contact force did correlate with impedance, unipolar, and bipolar electrogram amplitudes; however, there were large overlaps. Conclusions Antegrade vs. retrograde LV-mapping approaches result in different CF. A combined approach to the LV mapping may improve the overall LV mapping, potentially resulting in better clinical outcomes for the left VT catheter ablation. The previous surrogate markers used to assess CF do correlate with in vivo CF; however, due to a larger overlap, their clinical value is limited.

In Vivo Contact Force Analysis and Correlation With Tissue Impedance During Left Atrial Mapping and Catheter Ablation of Atrial Fibrillation

Background—The aim of this study was to evaluate in vivo contact force (CF) and the correlation of CF with impedance during left atrial 3-dimensional electroanatomical mapping and ablation. Methods and Results—CF during point-by-point left atrial mapping was assessed in 30 patients undergoing atrial fibrillation ablation. Operators were blinded to the real-time CF data. Data were analyzed according to 11 predefined areas in the left atrial and 6 segments around the ipsilateral pulmonary veins. A total of 3475 mapping and 878 ablation points were analyzed. Median CF during mapping was 14.0g (6.5–26.2; q1–q3), ranging from 5.1g at the ridge to 29.8g at the roof. Median CF at the ridge and mitral isthmus were 5.1g and 6.9g, respectively. Extremely high CF ≥100g was noted in 24 points (0.7%). Median CFs during ablation around the right and left pulmonary veins were 22.8g (12.6–37.9; q1–q3) and 12.3g (6.9–30.2; q1–q3), respectively. The lowest median CFs were recorded at the anterior–superior and anterior–inferior segments of the left pulmonary veins (7.2g and 7.9g). Impedance values during mapping and impedance fall during ablation correlated with the applied CF (R2=0.16; P<0.001 and R2=0.04; P<0.001) although there was significant overlap. Conclusions—Excessively high and low CF values can be observed during left atrial mapping and ablation. The low CF obtained at the mitral isthmus and anterior segments of the left pulmonary veins may explain why reconnection after ablation occurs more frequently at these sites. CF and impedance do correlate; however, the impedance for a given CF ranges widely, limiting its use in clinical practice.

Electrical isolation of a substrate after myocardial infarction: a novel ablation strategy for unmappable ventricular tachycardias—feasibility and clinical outcome

AIMSnCatheter ablation can abolish clinical ventricular tachycardia (VT) in patients after myocardial infarction (MI). However, VT frequently recurs after ablation. The best ablation strategy is still unknown, particularly in patients with unmappable VTs. We hypothesized that isolation of the arrhythmogenic substrate would be a feasible and effective ablation strategy for the treatment of ischaemic VT.nnnMETHODS AND RESULTSnTwelve patients (54 ± 8 years, left ventricular ejection fraction, LVEF 32 ± 13%) underwent catheter ablation for sustained VT (anterior MI = 10, inferior MI = 2). All patients had recurrent defibrillator shocks, including electrical storms in seven patients, despite anti-arrhythmic drugs. During electrophysiological study, 3 ± 2 VTs were induced. Three-dimensional mapping of the left ventricle revealed a low-voltage (<1.5 mV) area with fractionated electrograms and late potentials, with a mean area of 62 ± 20 cm(2). Isolation of the entire low-voltage area was attempted with a circumferential line along the low-voltage area border-zone. Substrate isolation was successfully achieved in 6 of 12 (50%) patients. Focal discharge within the isolated area was demonstrated in three of six (50%) patients. During a median follow-up of 479 [297; 781] days, 8 of 12 patients (66.7%) remained free of VT recurrence after a single procedure. In five of the six patients (83.3%) with successful substrate isolation, there were no VT recurrences when compared with three of the six patients (50%) with no substrate isolation.nnnCONCLUSIONnElectrical isolation of the entire substrate is feasible and appears to be an effective treatment in patients with late VT after MI.

Modified energy settings are mandatory to minimize oesophageal injury using the novel multipolar irrigated radiofrequency ablation catheter for pulmonary vein isolation.

AIMSnThe multipolar irrigated radiofrequency (RF) ablation catheter (nMARQ™) is a novel tool for pulmonary vein isolation (PVI). We investigated the incidence of thermal oesophageal injury (EI) using the nMARQ™ for PVI.nnnMETHODS AND RESULTSnIn the initial six patients (Group 1), RF was delivered at the posterior wall with a maximum duration of 60 s and a maximum power (maxP) of 20 W for unipolar ablation, and a maxP of 10 W for the bipolar ablation. In the latter 15 patients (Group 2), RF application was limited at the posterior wall to a maximum duration of 30 s and a maxP of 15 W for unipolar ablation a max P of 10 W for bipolar ablation. Oesophageal temperature monitoring was performed in all patients and ablation was terminated at a temperature rise >41°C. Endoscopy was carried out within 2 days post-ablation. Pulmonary vein isolation was performed during sinus rhythm and was successfully achieved in 83 of 84 PVs except the septal inferior vein in one patient. Charring was seen in 3 of 21 (14.3%) patients without any evidence of embolism. Phrenic nerve palsy occurred in one patient. Endoscopy revealed severe EI in 3 of 6 (50%) patients in Group 1 and in 1 of 15 patients (6.7%) in Group 2. Procedure times between Groups 1 and 2 were similar (228.3 ± 60.2 min vs. 221.3 ± 51.8 min; P = 0.79).nnnCONCLUSIONnAn unexpectedly high incidence of thermal EI was noted following PVI using the nMARQ™ with the initial ablation protocol. However, the incidence of thermal EI can be sigificantly reduced with limited power and RF application time at the posterior left atrium.

Long-Term Outcome After Catheter Ablation for Left Posterior Fascicular Ventricular Tachycardia Without Development of Left Posterior Fascicular Block

Long‐Term Outcome After Substrate‐Based Ablation of LPF VT During SR.u2002Background: Catheter ablation of left posterior fascicular (LPF) ventricular tachycardia (VT) is commonly performed during tachycardia. This study reports on the long‐term outcome of patients undergoing ablation of LPF VT targeting the earliest retrograde activation within the posterior Purkinje fiber network during sinus rhythm (SR).

Aborted Sudden Cardiac Death Due to Radiofrequency Ablation Within the Coronary Sinus and Subsequent Total Occlusion of the Circumflex Artery

We report a case of aborted sudden cardiac death and subsequent development of malignant drug‐refractory incessant ventricular tachycardia/fibrillation in a patient with acute coronary artery occlusion following radiofrequency ablation within the CS. Catheter ablation is a well‐established therapy for treatment of atrial fibrillation (AF). In patients with longstanding persistent AF extensive left atrial ablation and ablation inside the coronary sinus (CS) is frequently performed. Perimitral flutter following AF ablation is the most common form of left atrial macroreentry, especially in patients with previous ablation of complex fractionated electrograms and incomplete linear lesion sets within the left atrium. Successful ablation of this type of tachycardia is generally difficult and in about 60–70% patients requires additional ablation within the CS to achieve termination of tachycardia or/and left atrial isthmus (LAI) block. A limited number of case reports have been published describing acute coronary artery occlusion during or immediately after LAI ablation within the CS. This case exhibits a potential lethal risk of radiofrequency ablation within the CS.