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A 59-year-old male was admitted to the emergency room with signs of heart failure. The echocardiogram showed an extensive apical infarction with large mobile thrombi in the left ventricle. Doppler examination demonstrated apical rotating flow. Despite adequate anticoagulant therapy, the patient suffered a massive right-sided cerebral infarction leading to right ventricular cerebral compression. The thrombogenic risk of apical rotating flow and the need for anticoagulation are discussed. [ABSTRACT FROM AUTHOR]

Background: The subcutaneous implantable cardioverter-defibrillator (S-ICD) was developed to overcome the risk of lead-related complications associated with the transvenous implantable cardioverter-defibrillator (TV-ICD). In contrast to the TV-ICD, the S-ICD is a completely extrathoracic device. Subsequently, complications differ between these 2 implantable cardioverter-defibrillators, which might impact patient perceptions of the therapies. This prespecified secondary analysis of the PRAETORIAN trial evaluates differences in quality of life., Methods: The PRAETORIAN trial (A Prospective, Randomized Comparison of Subcutaneous and Transvenous Implantable Cardioverter Defibrillator Therapy) randomized patients with an implantable cardioverter-defibrillator indication, without the need for pacing to S-ICD or TV-ICD therapy. Two questionnaires were collected at baseline, discharge, 12 months, and 30 months. The Duke Activity Status Index measures cardiac-specific physical functioning, and the 36-Item Short Form Health Survey measures physical and mental well-being, with the subscales bodily pain and mental health being of interest in this analysis. Mann-Whitney U tests were used to compare study arms, and a mixed model was used to describe the questionnaire outcomes over time., Results: Patients were randomized to S-ICD (n=426) and TV-ICD (n=423). In the S-ICD group, 20% were women versus 19% in the TV-ICD group. The median age was 63 (interquartile range, 54-69) years in the S-ICD group versus 64 (interquartile range, 56-69) years in the TV-ICD group. There were no significant differences in the Duke Activity Status Index and 36-Item Short Form Health Survey subscales for bodily pain and mental health between the groups at any time point. Patients with a shock in the last 90 days had significantly lower scores for social functioning ( P =0.008) and role limitations due to emotional problems ( P =0.001) than patients without a shock, but this effect did not differ between treatment arms., Conclusions: In a large randomized cohort of patients with an S-ICD or TV-ICD, no difference in overall quality of life was observed. However, implantable cardioverter-defibrillator shocks resulted in a reduction in quality of life, regardless of the device type or appropriateness., Registration: URL: https://www.clinicaltrials.gov; Unique identifier: NCT01296022., Competing Interests: Dr Knops reports consultancy fees and research grants from Abbott, Boston Scientific, Medtronic, and Cairdac and has stock options from AtaCor Medical, Inc. Dr El Chami reports consultancy fees from Boston Scientific and Medtronic. Dr Mittal reports consultancy fees from Boston Scientific and Medtronic. K.M. Kooiman reports consultancy fees from Boston Scientific. Dr Lambiase reports educational and research grants from and is in the research board of Boston Scientific, and reports research grants from Abbott. Dr Vernooy reports consultancy fees from Medtronic and Abbott. M.C. Burke is a consultant and receives honoraria, as well as research grants from Boston Scientific and has equity in and is chief medical officer for AtaCor Medical, Inc. Dr Wright has consultancy arrangements with Boston Scientific and Medtronic and iRhythm and a research grant from Boston Scientific. Dr Nordbeck reports modest speaker honoraria from Biotronik, Boston Scientific, and Medtronic. Dr Miller reports consultancy fees from Boston Scientific. Dr Whinnett is an advisor for Boston Scientific and is on the advisory board for Medtronic and Abbot and reports speaker fees from Medtronic. The other authors report no conflicts.

Introduction: When electrical storm (ES) is amenable to neither antiarrhythmic drugs, nor deep sedation or catheter ablation, autonomic modulation may be considered. We report our experience with percutaneous left stellate ganglion block (PSGB) to temporarily suppress refractory ventricular arrhythmia (VA) in patients with structural heart disease., Methods: A retrospective analysis was performed at our institution of patients with structural heart disease and an implantable cardioverter defibrillator (ICD) who had undergone PSGB for refractory VA between January 2018 and October 2021. The number of times antitachycardia pacing (ATP) was delivered and the number of ICD shocks/external cardioversions performed in the week before and after PSGB were evaluated. Charts were checked for potential complications., Results: Twelve patients were identified who underwent a combined total of 15 PSGB and 5 surgical left cardiac sympathetic denervation procedures. Mean age was 73 ± 5.8 years and all patients were male. Nine of 12 (75%) had ischaemic cardiomyopathy, with the remainder having non-ischaemic dilated cardiomyopathy. Mean left ventricular ejection fraction was 35% (± 12.2%). Eight of 12 (66.7%) patients were already being treated with both amiodarone and beta-blockers. The reduction in ATP did not reach statistical significance (p = 0.066); however, ICD shocks (p = 0.028) and ATP/shocks combined were significantly reduced (p = 0.04). At our follow-up electrophysiology meetings PSGB was deemed ineffective in 4 of 12 patients (33%). Temporary anisocoria was seen in 2 of 12 (17%) patients, and temporary hypotension and hoarseness were reported in a single patient., Discussion: In this limited series, PSGB showed promise as a method for temporarily stabilising refractory VA and ES in a cohort of male patients with structural heart disease. The side effects observed were mild and temporary., (© 2024. The Author(s).)

Background: In the Rate Control versus Electrical Cardioversion Trial 7-Acute Cardioversion versus Wait and See, patients with recent-onset atrial fibrillation (AF) were randomized to either early or delayed cardioversion., Aim: This prespecified sub-analysis aimed to evaluate heart rate during AF recurrences after an emergency department (ED) visit identified by an electrocardiogram (ECG)-based handheld device., Methods: After the ED visit, included patients (n = 437) were asked to use an ECG-based handheld device to monitor for recurrences during the 4-week follow-up period. 335 patients used the handheld device and were included in this analysis. Recordings from the device were collected and assessed for heart rhythm and rate. Optimal rate control was defined as a target resting heart rate of <110 beats per minute (bpm)., Results: In 99 patients (29.6%, mean age 67 ± 10 years, 39.4% female, median 6 [3-12] AF recordings) a total of 314 AF recurrences (median 2 [1-3] per patient) were identified during follow-up. The average median resting heart rate at recurrence was 100 ± 21 bpm in the delayed vs 112 ± 25 bpm in the early cardioversion group (p = .011). Optimal rate control was seen in 68.4% [21.3%-100%] and 33.3% [0%-77.5%] of recordings (p = .01), respectively. Randomization group [coefficient -12.09 (-20.55 to -3.63, p = .006) for delayed vs. early cardioversion] and heart rate on index ECG [coefficient 0.46 (0.29-0.63, p < .001) per bpm increase] were identified on multivariable analysis as factors associated with lower median heart rate during AF recurrences., Conclusion: A delayed cardioversion strategy translated into a favorable heart rate profile during AF recurrences., (© 2023 The Authors. Clinical Cardiology published by Wiley Periodicals, LLC.)

Background: The subcutaneous implantable cardioverter-defibrillator (S-ICD) is developed to overcome lead-related complications and systemic infections, inherent to transvenous ICD (TV-ICD) therapy. The PRAETORIAN trial demonstrated that the S-ICD is non-inferior to the TV-ICD with regard to the combined primary endpoint of inappropriate shocks and complications. This prespecified secondary analysis evaluates all complications in the PRAETORIAN trial., Methods and Results: The PRAETORIAN trial is an international, multicentre, randomized trial in which 849 patients with an indication for ICD therapy were randomized to receive an S- ICD (N = 426) or TV-ICD (N = 423) and followed for a median of 49 months. Endpoints were device-related complications, lead-related complications, systemic infections, and the need for invasive interventions. Thirty-six device-related complications occurred in 31 patients in the S-ICD group of which bleedings were the most frequent. In the TV-ICD group, 49 complications occurred in 44 patients of which lead dysfunction was most frequent (HR: 0.69; P = 0.11). In both groups, half of all complications were within 30 days after implantation. Lead-related complications and systemic infections occurred significantly less in the S-ICD group compared with the TV-ICD group (P < 0.001, P = 0.03, respectively). Significantly more complications required invasive interventions in the TV-ICD group compared with the S-ICD group (8.3% vs. 4.3%, HR: 0.59; P = 0.047)., Conclusion: This secondary analysis shows that lead-related complications and systemic infections are more prevalent in the TV-ICD group compared with the S-ICD group. In addition, complications in the TV-ICD group were more severe as they required significantly more invasive interventions. This data contributes to shared decision-making in clinical practice., Competing Interests: Conflict of interest: R.E.K reports consultancy fees and research grants from Abbott, Boston Scientific, Medtronic, and Cairdac and has stock options from AtaCor Medical Inc. S.M. reports consultancy fees from Boston Scientific. K.V. reports consultancy fees from Medtronic and Abbott. M.C.B. is a consultant and receives honoraria, as well as research grants from Boston Scientific and has equity in and is chief medical officer for AtaCor Medical, Inc. D.J.W. has consultancy arrangements with Boston Scientific and Medtronic and a research grant from Boston Scientific. P.N. reports modest speaker honoraria from Biotronik, Boston Scientific, and Medtronic. M.A.M. reports consultancy fees from Boston Scientific. Z.I.W. is an advisor for Boston Scientific and on the advisory board for Medtronic and Abbot and reports speaker fees from Medtronic. The other authors report no conflicts., (© The Author(s) 2022. Published by Oxford University Press on behalf of European Society of Cardiology.)

Objective: The Rate Control versus Electrical Cardioversion Trial 7-Acute Cardioversion versus Wait and See trial compared early to delayed cardioversion for patients with recent-onset symptomatic atrial fibrillation (AF). This study aims to evaluate the adherence to a 4-week mobile health (mHealth) prescription to detect AF recurrences after an emergency department visit., Methods: After the emergency department visit, the 437 included patients, irrespective of randomisation arm (early or delayed cardioversion), were asked to record heart rate and rhythm for 1 min three times daily and in case of symptoms by an electrocardiography-based handheld device for 4 weeks (if available). Adherence was appraised as number of performed measurements per number of recordings asked from the patient and was evaluated for longitudinal adherence consistency. All patients who used the handheld device were included in this subanalysis., Results: 335 patients (58% males; median age 67 (IQR 11) years) were included. The median overall adherence of all patients was 83.3% (IQR 29.9%). The median number of monitoring days was 27 out of 27 (IQR 5), whereas the median number of full monitoring days was 16 out of 27 (IQR 14). Higher age and a previous paroxysm of AF were identified as multivariable adjusted factors associated with adherence., Conclusions: In this randomised trial, a 4-week mHealth prescription to monitor for AF recurrences after an emergency department visit for recent-onset AF was feasible with 85.7% of patients consistently using the device with at least one measurement per day. Older patients were more adherent., Trial Registration Number: NCT02248753., Competing Interests: Competing interests: JL has a consultancy agreement with Medtronic and has received speakers fee from Bayer and Novartis, and a research grant ZonMW LEAP trial project number 852002101. MR has received consultancy fees from Medtronic, Arca Biopharma and Roche to the institution, unrestricted research grant from ZonMW and the Dutch Heart Foundation; DECISION project 848090001. Unrestricted research grants from the Netherlands Cardiovascular Research Initiative: an initiative with support of the Dutch Heart Foundation; RACE V (CVON2014-9), RED-CVD (CVON2017-11). Unrestricted research grant from Top Sector Life Sciences & Health to the Dutch Heart Foundation (PPP Allowance; CVON-AI (2018B017)). Unrestricted research grant from the European Union’s Horizon 2020 research and innovation programme under grant agreement; EHRA-PATHS (945260). IVG has received consultancy fees Institute from Medtronic, Daiichi, BMS, Bayer and Roche to the institution, unrestricted research grants from the Netherlands Cardiovascular Research Initiative: an initiative with support of the Dutch Heart Foundation; unrestricted research grant from the European Union’s Horizon 2020 research and innovation programme under grant agreement; EHRA-PATHS (945260)., (© Author(s) (or their employer(s)) 2023. No commercial re-use. See rights and permissions. Published by BMJ.)

Background: The PRAETORIAN trial (A Prospective, Randomized Comparison of Subcutaneous and Transvenous Implantable Cardioverter Defibrillator Therapy) showed noninferiority of subcutaneous implantable cardioverter defibrillator (S-ICD) compared with transvenous implantable cardioverter defibrillator (TV-ICD) with regard to inappropriate shocks and complications. In contrast to TV-ICD, S-ICD cannot provide antitachycardia pacing for monomorphic ventricular tachycardia. This prespecified secondary analysis evaluates appropriate therapy and whether antitachycardia pacing reduces the number of appropriate shocks., Methods: The PRAETORIAN trial was an international, investigator-initiated randomized trial that included patients with an indication for implantable cardioverter defibrillator (ICD) therapy. Patients with previous ventricular tachycardia <170 bpm or refractory recurrent monomorphic ventricular tachycardia were excluded. In 39 centers, 849 patients were randomized to receive an S-ICD (n=426) or TV-ICD (n=423) and were followed for a median of 49.1 months. ICD programming was mandated by protocol. Appropriate ICD therapy was defined as therapy for ventricular arrhythmias. Arrhythmias were classified as discrete episodes and storm episodes (≥3 episodes within 24 hours). Analyses were performed in the modified intention-to-treat population., Results: In the S-ICD group, 86 of 426 patients received appropriate therapy, versus 78 of 423 patients in the TV-ICD group, during a median follow-up of 52 months (48-month Kaplan-Meier estimates 19.4% and 17.5%; P =0.45). In the S-ICD group, 83 patients received at least 1 shock, versus 57 patients in the TV-ICD group (48-month Kaplan-Meier estimates 19.2% and 11.5%; P =0.02). Patients in the S-ICD group had a total of 254 shocks, compared with 228 shocks in the TV-ICD group ( P =0.68). First shock efficacy was 93.8% in the S-ICD group and 91.6% in the TV-ICD group ( P =0.40). The first antitachycardia pacing attempt successfully terminated 46% of all monomorphic ventricular tachycardias, but accelerated the arrhythmia in 9.4%. Ten patients with S-ICD experienced 13 electrical storms, versus 18 patients with TV-ICD with 19 electrical storms. Patients with appropriate therapy had an almost 2-fold increased relative risk of electrical storms in the TV-ICD group compared with the S-ICD group ( P =0.05)., Conclusions: In this trial, no difference was observed in shock efficacy of S-ICD compared with TV-ICD. Although patients in the S-ICD group were more likely to receive an ICD shock, the total number of appropriate shocks was not different between the 2 groups. Registration: URL: https://www.clinicaltrials.gov; Unique identifier: NCT01296022.

Background: Low oesophageal temperatures (OTs) during cryoballoon pulmonary vein isolation (PVI) have been associated with complications. This study assessed the incidence of low OT in clinical practice during cryoballoon PVI and verified possible predictive values for low OT., Methods: Consecutive patients who underwent PVI using the second-generation cryoballoon were retrospectively included. The distance from the oesophagus to the different pulmonary veins (PVs) (OP distance), body mass index (BMI), sex, age, balloon temperature and application time were studied as potential predictors of low OTs. Computed tomography was performed before the procedure to determine the OP distance. OT was measured using an oesophageal temperature probe. Applications were ended prematurely if the OT reached <16 °C. Low and ultralow OT were defined as OT <20 and <16 °C respectively., Results: Two hundred and four patients were included. Low OT was observed in 54 patients (26%) and 27 patients (13%) reached ultralow OTs. OP distance was the only predictor of low OTs after multivariate analysis. A cut-off value of 19 mm showed 96.2% sensitivity and 37.8% specificity in predicting low OTs. No clinically relevant relation was found between low OTs and BMI, age, sex, balloon temperature or application duration., Conclusions: The incidence of low OT was 26% for cryoballoon PVI. OP distance was the only predictor of low OTs. Since an OP distance <19 mm was present in all patients in at least one PV, we recommend routine OT measurement during PVI cryoballoon therapy to prevent oesophagus-related complications.

Background: In the 123-study, we prospectively assessed, in a randomized fashion, the minimal cryoballoon application time necessary to achieve pulmonary vein (PV) isolation (PVI) in patients with paroxysmal atrial fibrillation (AF) with the aim to reduce complications by shortening the application duration. The first results of this study demonstrated that shortened cryoballoon applications (<2 minutes) resulted in less phrenic nerve injury (PNI) without compromising acute isolation efficacy for the right PVs. We now report the 1-year follow-up results regarding safety and efficacy of shorter cryoballoon applications., Methods: A total of 222 patients with AF were randomized to two applications of 1 min "short," 2 min "medium," or 3 min "long" duration, 74 per group. Recurrence of AF and PV reconduction at 1-year follow-up were assessed., Results: The overall 1-year freedom from AF was 79% and did not differ significantly between the short, medium, and long application groups (77%, 74%, and 85% for short, medium, and long application groups, respectively; P = 0.07). In 30 patients, a redo PVI procedure was performed. For all four PVs, there was no significant difference in reconduction between the three groups. Reconduction was most common in the left superior PV (57%). The right superior PV (RSPV) showed significantly less reconduction (17%) compared to the other PVs., Conclusions: Shortening cryoballoon applications of the RSPV to <2 minutes results in less PNI, while acute success and 1-year freedom from AF are not compromised. Therefore, shorter cryoballoon applications (especially) in the RSPV could be used to reduce PNI., (© 2020 The Authors. Pacing and Clinical Electrophysiology published by Wiley Periodicals LLC.)

Background: The second-generation cryoballoon significantly improves outcome of pulmonary vein isolation (PVI) but may cause more complications than the first generation. Currently, no consensus regarding optimal cryoballoon application time exists. The 123-study aimed to assess the minimal cryoballoon application duration necessary to achieve PVI (primary endpoint) and the effect of application duration on prevention of phrenic nerve injury (PNI)., Methods: Patients <75 years of age with paroxysmal atrial fibrillation, normal PV anatomy, and left atrial size <40 cc/m² or <50 mm were randomized to two applications of different duration: "short," "medium," or "long." A total of 222 patients were enrolled, 74 per group., Results: Duration per application was 105 (101-108), 164 (160-168), and 224 (219-226) s and isolation was achieved in 79, 89, and 90% (P < 0.001) of the PVs after two applications in groups short, medium, and long, respectively. Only for the left PVs, the success rate of the short group was significantly less compared to the medium- and long-duration groups (P < 0.001). PNI during the procedure occurred in 19 PVs (6.5%) in the medium and in 20 PVs (6.8%) in the long duration groups compared to only five PVs (1.7%) in the short duration group (P < 0.001)., Conclusions: Short cryoballoon ablation application times, less than 2 min, did affect the success for the left PVs but not for the right PVs and resulted in less PNI. A PV tailored approach with shorter application times for the right PVs might be advocated., (© 2019 The Authors. Pacing and Clinical Electrophysiology published by Wiley Periodicals, Inc.)

Background: Patients with recent-onset atrial fibrillation commonly undergo immediate restoration of sinus rhythm by pharmacologic or electrical cardioversion. However, whether immediate restoration of sinus rhythm is necessary is not known, since atrial fibrillation often terminates spontaneously., Methods: In a multicenter, randomized, open-label, noninferiority trial, we randomly assigned patients with hemodynamically stable, recent-onset (<36 hours), symptomatic atrial fibrillation in the emergency department to be treated with a wait-and-see approach (delayed-cardioversion group) or early cardioversion. The wait-and-see approach involved initial treatment with rate-control medication only and delayed cardioversion if the atrial fibrillation did not resolve within 48 hours. The primary end point was the presence of sinus rhythm at 4 weeks. Noninferiority would be shown if the lower limit of the 95% confidence interval for the between-group difference in the primary end point in percentage points was more than -10., Results: The presence of sinus rhythm at 4 weeks occurred in 193 of 212 patients (91%) in the delayed-cardioversion group and in 202 of 215 (94%) in the early-cardioversion group (between-group difference, -2.9 percentage points; 95% confidence interval [CI], -8.2 to 2.2; P = 0.005 for noninferiority). In the delayed-cardioversion group, conversion to sinus rhythm within 48 hours occurred spontaneously in 150 of 218 patients (69%) and after delayed cardioversion in 61 patients (28%). In the early-cardioversion group, conversion to sinus rhythm occurred spontaneously before the initiation of cardioversion in 36 of 219 patients (16%) and after cardioversion in 171 patients (78%). Among the patients who completed remote monitoring during 4 weeks of follow-up, a recurrence of atrial fibrillation occurred in 49 of 164 patients (30%) in the delayed-cardioversion group and in 50 of 171 (29%) in the early-cardioversion group. Within 4 weeks after randomization, cardiovascular complications occurred in 10 patients and 8 patients, respectively., Conclusions: In patients presenting to the emergency department with recent-onset, symptomatic atrial fibrillation, a wait-and-see approach was noninferior to early cardioversion in achieving a return to sinus rhythm at 4 weeks. (Funded by the Netherlands Organization for Health Research and Development and others; RACE 7 ACWAS ClinicalTrials.gov number, NCT02248753.)., (Copyright © 2019 Massachusetts Medical Society.)

Aims: Cryoballoon pulmonary vein (PV) isolation in patients with atrial fibrillation has proven to be effective in short-term and long-term follow-up. To visualise the PV anatomy, pre-ablation contrast pulmonary venography is commonly performed. Three-dimensional (3D) computed tomography (CT) overlay is a new technique creating a live 3D image of the left atrium by integrating a previously obtained CT scan during fluoroscopy. To evaluate the benefits of 3D CT overlay during cryoballoon ablation, we studied the use of 3D CT overlay versus contrast pulmonary venography in a randomised fashion in patients with paroxysmal atrial fibrillation undergoing cryoballoon PV isolation., Methods and Results: Between October 2012 and June 2013, 30 patients accepted for PV isolation were randomised to cryoballoon PV isolation using either 3D CT overlay or contrast pulmonary venography. All patients underwent a pre-procedural cardiac CT for evaluation of the anatomy of the left atrium (LA) and the PVs. In the 3D CT overlay group, a 3D reconstruction of the LA and PVs was made. An overlay of the CT reconstruction was then projected over live fluoroscopy. Patients in the contrast pulmonary venography group received significantly more contrast agent (77.1 ± 21.2 cc vs 40.1 ± 17.6 cc, p < 0.001) and radiation (43.0 ± 21.9 Gy.cm2 vs 28.41 ± 11.7 Gy.cm2, p = 0.04) than subjects in the 3D CT overlay group. There was no difference in total procedure time, fluoroscopy time and the amount of cryoapplications between the two groups., Conclusion: The use of 3D CT overlay decreases radiation and contrast dye exposure and can assist in guiding cryoballoon-based PV isolation.

Background: Sustained ventricular tachycardia (susVT) and ventricular fibrillation (VF) are observed in adult patients with congenital heart disease (CHD). These dysrhythmias may be preceded by non-sustained ventricular tachycardia (NSVT). The aims of this study are to examine the 1] time course of ventricular tachyarrhythmia (VTA) in a large cohort of patients with various CHDs and 2] the development of susVT/VF after NSVT., Methods: In this retrospective study, patients with VTA on ECG, 24-hour Holter or ICD-printout or an out-of-hospital-cardiac arrest due to VF were included. In patients with an ICD, the number of shocks was studied., Results: Patients (N=145 patients, 59% male) initially presented with NSVT (N=103), susVT (N=25) or VF (N=17) at a mean age of 40 ± 14 years. Prior to VTA, 58 patients had intraventricular conduction delay, 14 an impaired ventricular dysfunction and 3 had coronary artery disease. susVT/VF rarely occurred in patients with NSVT (N=5). Fifty-two (36%) patients received an ICD; appropriate and inappropriate shocks, mainly due to supraventricular tachycardia (SVT), occurred in respectively 15 (29%) (NSVT: N=1, susVT: N=9, VF: N=5) and 12 (23%) (NSVT: N=4, susVT: N=5, VF: N=3) patients., Conclusions: VTA in patients with CHD appear on average at the age of 40 years. susVT/VF rarely developed in patients with only NSVT, whereas recurrent episodes of susVT/VF frequently developed in patients initially presenting with susVT/VF. Hence, a wait-and-see treatment strategy in patients with NSVT and aggressive therapy of both episodes of VTA and SVT in patients with susVT/VF seems justified., (Copyright © 2016 Elsevier Ireland Ltd. All rights reserved.)

Background: The incidence of atrial fibrillation (AF) is rising in the aging patients with congenital heart defects (CHD). However, studies reporting on AF in patients with CHD are scarce. The aim of this multicenter study was to examine in a large cohort of patients with a variety of CHD: (1) the age of onset and initial treatment of AF, coexistence of atrial tachyarrhythmia and (2) progression of paroxysmal to (long-standing) persistent/permanent AF during long-term follow-up., Methods and Results: Patients (n=199) with 15 different CHD and documented AF episodes were studied. AF developed at 49±17 years. Regular atrial tachycardia (AT) coexisting with AF occurred in 65 (33%) patients; 65% initially presented with regular AT. At the end of a follow-up period of 5 (0-24) years, the ECG showed AF in 81 patients (41%). In a subgroup of 114 patients, deterioration from paroxysm of AF to (long-standing) persistent/permanent AF was observed in 29 patients (26%) after only 3 (0-18) years of the first AF episode. Cerebrovascular accidents/transient ischemic attacks occurred in 26 patients (13%), although a substantial number (n=16) occurred before the first documented AF episode., Conclusions: Age at development of AF in patients with CHD is relatively young compared with the patients without CHD. Coexistence of episodes of AF and regular AT occurred in a considerable number of patients; most of them initially presented with regular AT. The fast and frequent progression from paroxysmal to (long-standing) persistent or permanent AF episodes justifies close follow-up and early, aggressive therapy of both AT and AF., (© 2015 American Heart Association, Inc.)

Background and Purpose: The electromechanical window (EMW), the interval between the end of the T-wave and the end of the left ventricular pressure (LVP) curve, has recently been proposed as a predictor of risk of Torsade de Pointes (TdP) in healthy animals, whereby a negative EMW (mechanical relaxation earlier than repolarization) after drug administration indicates an increased TdP risk. The aims of this study were to assess (i) the effect of the ventricular remodelling in the canine chronic, complete atrioventricular block (CAVB) model on EMW; (ii) the effect of the I(Kr) -blocker dofetilide on EMW; and (iii) the correlation of EMW with TdP inducibility., Experimental Approach: Our 11 year database of experiments of CAVB in dogs under general anaesthesia was reviewed and experiments included if ECG and LVP were recorded simultaneously at spontaneous rhythm. In total, 89 experiments in 44 dogs were appropriate and were analysed., Key Results: During normally conducted sinus rhythm or acute atrioventricular block, EMW was positive. During CAVB, EMW was decreased to negative values. Dofetilide further reduced EMW before inducing repetitive TdP in 82% of the experiments. However, subclassification into inducible and non-inducible dogs revealed no difference in EMW. Analysis of the components of EMW revealed that the observed changes in EMW were solely caused by QT prolongation., Conclusions and Implications: In the canine CAVB model, ventricular remodelling and I(Kr) block by dofetilide are associated with negative EMW values, but this reflects QT prolongation, and implies that the EMW lacks specificity to predict dofetilide-induced TdP., (© 2013 The British Pharmacological Society.)

Aims: The 5 French Sorin Hepta 4B lead is a bipolar transvenous pacemaker lead with a passive fixation mechanism. From 2003 to 2008, a total of 98 Sorin Hepta 4B right ventricular pacemaker leads were implanted in our hospital. We observed an unexpected high failure rate of this pacemaker lead. The aim of this study is to determine the performance of the Hepta 4B lead., Methods and Results: A retrospective single-centre survey was conducted on the performance of all implanted Hepta 4B leads in our high-volume tertiary hospital. Information on all implants was stored in a database. Analysis of this database and patients' charts was performed to assess the rate of complications of all implanted Hepta 4B leads. Median time of follow-up was 5.49 (4.15-6.44) years. Of the 98 implanted Hepta 4B leads, 21 (21%) were replaced. A total of 18 (18%) leads showed electrical malfunction, leading to symptoms in five (5%) patients. Electrical malfunction included impedance change, threshold rise, and sensing problems., Conclusion: In this single-centre retrospective observation we report an extreme and unexpected failure rate of the Sorin Hepta lead. The most common complication was electrical dysfunction. The reason for this phenomenon has to be analysed, but the co-radial multifilar design, allowing a smaller diameter of the lead, may explain this finding.

Background: Although atrial fibrillation (AF) is the most commonly encountered arrhythmia, some of the properties make its detection challenging. In daily practice, underdiagnosis can lead to less effective treatment in prevention of stroke. Based on data from studies on treatment of AF, more intensive follow-up strategies, including 7-day Holter recording, 30-day event recording, and even implantable cardiac monitoring devices, are suggested. The study purpose is to evaluate the performance of a continuous single-channel loop recorder with automatic AF detection and transtelephonic electrocardiogram (ECG) transmission capabilities., Methods and Results: A consecutive cohort of 153 patients admitted to the stroke unit with a presumptive diagnosis of ischemic cerebrovascular accident was screened for AF. Twenty-four-hour rhythm observation was performed using a single-channel external loop recorder (ELR) configured for automated AF detection. A total of 45 patients with a known history of AF, AF on the admission ECG, or incomplete registrations were excluded. Extensive additional frequency-based settings were used to establish a reference registration. In total, 2923 recordings were transmitted. We evaluated all events, of which 1190 were designated by the device as AF. The sensitivity, specificity, PPV, and NPV for identifying AF using the ELR were, respectively, 93%, 51%, 5%, and 99%., Conclusions: In this ELR validation study, the dedicated AF detection algorithm showed to be highly sensitive but not specific for AF. Applicability of an ELR might be limited for efficacious detection of AF, as manual verification is mandatory for a vast amount of recordings., (©2013 Wiley Periodicals, Inc.)

Aims: Although cardiac resynchronisation therapy (CRT) is an established treatment to improve cardiac function, a significant amount of patients do not experience noticeable improvement in their cardiac function. Optimal timing of the delay between atrial and ventricular pacing pulses (AV delay) is of major importance for effective CRT treatment and this optimum may differ between resting and exercise conditions. In this study the feasibility of haemodynamic measurements by the non-invasive finger plethysmographic method (Nexfin) was used to optimise the AV delay during exercise., Methods and Results: Thirty-one patients implanted with a CRT device in the last 4 years participated in the study. During rest and in exercise, stroke volume (SV) was measured using the Nexfin device for several AV delays. The optimal AV delay at rest and in exercise was determined using the least squares estimates (LSE) method. Optimisation created a clinically significant improvement in SV of 10 %. The relation between HR and the optimal AV delay was patient dependent., Conclusion: A potential increase in SV of 10 % can be achieved using Nexfin for optimisation of AV delay during exercise. A considerable number of patients showed benefit with lengthening of the AV delay during exercise.

Introduction: A number of predisposing factors have been suggested to be contributing to drug-induced torsade de pointes (TdP) arrhythmias: short-long-short (SLS) sequence, bradycardia, timing of drug administration, anaesthesia, ventricular remodelling, and altered ventricular activation due to ventricular ectopic beats (SLS) or idioventricular rhythm (IVR). Chronic atrio-ventricular (AV)-block (CAVB) dogs are susceptible to dofetilide-induced TdP., Methods and Results: In 32 anaesthetized animals, the relevance of ventricular remodelling for TdP susceptibility was studied by dofetilide [0.025 mg/kg/5 min intravenously (iv)] during bradycardia in the presence (CAVB, n= 18) or absence [acute atrio-ventricular block (AVB), n= 32] of ventricular remodelling. In sub-protocols, the possible pro-arrhythmic effects of timing of dofetilide administration: prior to (n= 11), or after creation of AVB (n= 9) and relevance of SLS pacing (n= 17) was investigated during IVR. Dofetilide was also given after AVB when the activation of the ventricles was normal: pacing (1000 ms) from the high septum (n= 7) or abnormal but fixed from the left ventricular apex (n= 5). Torsade de pointes inducibility was defined as reproducible (≥ 3 times) occurrence. In acute AV block (AAVB), dofetilide did not induce TdP spontaneously (0 of 32), whereas TdP was seen in 10 out of 18 serially tested dogs in CAVB (P< 0.001). The other factors: timing of dofetilide (0 of 11 vs. 0 of 9), SLS pacing (0 of 17 vs. 1 of 17), or ventricular activation (0 of 7 vs. 0 of 5) did not increase TdP susceptibility. Beat-to-beat variability of repolarization increased after ventricular remodelling and was highest prior to TdP induction., Conclusion: In AAVB dogs, TdP is not spontaneously seen, whereas it is present in CAVB. This implies that ventricular remodelling is a prerequisite for TdP induction in this model.

Background: Recent studies have demonstrated that radiofrequency isolation of the pulmonary veins (PVI) is an effective treatment for symptomatic atrial fibrillation. Based on these positive results, non- pharmacological therapy has been incorporated in the guidelines for drug refractory atrial fibrillation, resulting in an increased popularity. The prevention of thromboembolic complications remains an important issue., Methods: In January 2010, we adopted an anticoagulation strategy based on continuation of vitamin K antagonists (VKAs) and selective use of transoesophageal echocardiogram (TEE). We retrospectively analysed the results of this strategy in all patients referred for PVI treatment. VKAs were started for all patients 2 months prior to treatment. Discontinuation of oral anticoagulation was considered 3 months after treatment based on thromboembolic and bleeding risk profile. Bleeding and thromboembolic complications were registered during outpatient clinic follow-up up until 3 months., Results: We performed 151 PVI procedures from January 2010 to March 2011. All patients were seen 6 weeks after discharge. No transient ischaemic accidents or ischaemic cerebrovascular incidents occurred pre-, peri- or postprocedure. Four (2.7%) procedures were complicated by tamponade requiring pericardiocentesis., Conclusions: Our data support the increasing evidence for continuation of periprocedural administration of VKAs complemented by a selective TEE approach as a safe therapy for thromboembolic complications.

Frequent monomorphic ventricular premature beats (VPBs) may lead to left ventricular dysfunction. We describe two patients with frequent monomorphic VPBs and dilated cardiomyopathy in whom left ventricular function normalised after elimination of the VPBs by radiofrequency catheter ablation. The recent literature on this topic is summarised and potential candidates for catheter ablation are discussed. (Neth Heart J 2010;18:493-8.).

Para-Hisian pacing at high output simultaneously captures the His bundle or proximal right bundle, as well as the adjacent ventricular myocardium. At lower output, direct His-bundle, or right-bundle, capture is lost which causes an increase in the stimulus to atrium interval. We describe a case with an increment of 68 ms with capture of the His bundle. This seems to be a paradoxical response, which however can be explained by the presence of retrograde dual AV-node physiology. Continuation of this phenomenon could be related to concealed anterograde invasion of the fast pathway thereby maintaining the retrograde activation during para-Hisian pacing on the slow pathway despite paced cycle lengths (His to His intervals) where retrograde fast pathway conduction proved to be possible.

We describe the development of a Brugada ECG together with sinus- and ventricular arrest after intravenous flecainide for atrial fibrillation in a patient in whom eventually a SCN5a mutation was identified. Unrecognized SCN5A mutations could underlie class IC-induced sinus arrest and conduction defects in some patients.

We describe a cardiac tamponade after venous graft perforation due to stent inflation. The complications and therapeutic options are discussed.

A 69-year old male with a large pulmonary embolism is described before and after thrombolytic treatment. The echocardiographic and electrocardiographic hallmarks of right ventricular pressure overload and dilatation are illustrated.

Objective: Acquired long-QT syndrome in combination with increased beat-to-beat variability of repolarisation duration (BVR) is associated with lethal torsades de pointes arrhythmias (TdP) in dogs with remodelled heart after atrioventricular block (AVB). We evaluated the relative contributions of bradycardia and ventricular remodelling to proarrhythmic BVR with and without pharmacological I(Kr) block in order to identify the individual at risk., Methods: Three groups of dogs were used: sinus rhythm dogs (n = 12), dogs with acute AVB (n = 8), and dogs with >3 weeks chronic AVB (n = 27). Under anaesthesia, ECG and monophasic action potential duration (MAPD) were measured. Local BVR was quantified as short-term variability from 30 consecutive left ventricular MAPD (STV = summation absolute value(D(n(i)-D(n+1))/[30 x square root of 2])). All dogs received dofetilide iv., Results: The slower ventricular rate acutely after AVB affected neither QTc nor STV (288+/-18 to 293+/-38 ms and 0.7+/-0.1 to 0.7+/-0.1 ms, respectively; P = NS for both), whereas ventricular remodelling increased both (to 376+/-46 and 2.3+/-0.6 ms, respectively; P < 0.05 for both). Neither dogs in sinus rhythm nor acute AVB showed any TdP, whereas dofetilide induced TdP in 74% of the chronic-AVB dogs. Dofetilide increased the QTc interval in all groups (19-24%; P < 0.05 for all groups), whereas STV was elevated in chronic-AVB dogs only (to 4.2+/-1.5 ms; P < 0.05) and further confined to inducible chronic-AVB dogs (5.0+/-0.8 versus 1.9+/-0.4 ms for resistant dogs; P < 0.05). Variability of the idioventricular rate was increased directly after AVB and did not influence BVR., Conclusions: Under drug-free circumstances, a persistent high BVR in chronic-AVB dogs is remodelling dependent rather than a direct consequence of bradycardia acutely after AVB. Variability of this slower rate does not influence BVR. Dofetilide causes a transient increase in BVR only in proarrhythmic dogs. Thus, BVR may aid the identification of the TdP-susceptible patient.

Increased proarrhythmia in dogs with chronic AV block (AVB) has been explained by ventricular remodeling causing a decrease in repolarization reserve. Beat-to-beat variability of repolarization (BVR) has been suggested to reflect repolarization reserve, in which high variability represents diminished reserve and larger propensity for repolarization-dependent ventricular arrhythmia. A subset of chronic AVB dogs (10%) suffers sudden cardiac death (SCD). With the assumption that repolarization defects constitute a potentially lethal proarrhythmic substrate, we hypothesized that BVR in SCD dogs are larger than in matched control chronic AVB dogs. From a population of 200 chronic AVB dogs, initially two groups were chosen retrospectively: 8 dogs that died suddenly (SCD) and 8 control dogs. Control dogs had a longer lifespan after AVB (10 to 18 weeks) than SCD dogs (5 to 10 weeks). All dogs had undergone electrophysiological testing under anesthesia where ECG, left and right ventricular endocardial monophasic action potentials (MAP) were recorded. BVR was assessed from 30 consecutive beats, illustrated by Poincare plots and was the only parameter discriminating between SCD and control group. All other electrophysiological parameters (RR, QT and MAP durations) were comparable for the two groups. Extending the number of animals and groups confirmed a larger BVR in the SCD group (SCD: 5.1 +/- 2.7; n = 11 versus control: 2.5 +/- 0.4 ms; n = 61; P < 0.05) and showed reverse-use dependence of BVR. In comparison, dogs with acute AVB had low variability (1.3 +/- 0.3 ms; n = 9; P < 0.05 versus chronic AVB). Cardiac electrical remodeling after AVB is associated with an increase in beat-to-beat variability of repolarization. Chronic AVB dogs displaying further elevated variability of repolarization are prone to arrhythmia-related SCD.

Few published human data are available concerning the acute toxicity of the new antiepileptic drug oxcarbazepine of which the metabolite 10- monohydroxy derivate (MHD) is the pharmacologically effective compound. Two hours after a documented overdosage of more than 100 tablets oxcarbazepine, the serum level of the parent compound was 10-fold higher than the therapeutic dosage (31.6 mg l(-1)). However, the concentration of MHD, which peaked 7 h after intake, was only twofold higher (59.0 mg l(-1)). No life-threatening situations occurred and the patient fully recovered. The fact that oxcarbazepine is a prodrug and that the formation of the active MHD metabolite is a rate-limiting process may contribute to the relative low toxicity of the drug in overdose.

Objective: Left ventricular hypertrophy has been associated with the prolongation of QT-time, and an increased risk of ventricular arrhythmias. The renin angiotensin system has been implicated in the development of ventricular hypertrophy. At 5 weeks complete AV block (CAVB) in the dog, there is: (1) biventricular hypertrophy associated with a transient activation of components of the renin angiotensin system, (2) increased APD, more pronounced in the left than in the right ventricle leading to spatial dispersion of repolarization, and (3) enhanced susceptibility to drug-induced torsade de pointes arrhythmias. To investigate whether these remodeling processes develop in parallel, time dependency was assessed in absence or presence of the AT1 receptor-blocker Irbesartan., Methods and Results: Dogs in sinus rhythm, 2 and 5 weeks CAVB were compared to dogs chronically treated with Irbesartan (30 mg/kg BID). Endocardial monophasic APD of left and right ventricle was measured and susceptibility to torsade de pointes was tested by infusing Dofetilide (0.025 mg/kg/5'). Hypertrophy was determined by relating heart-to-body weight at sacrifice. Left ventricular APD had increased more than right ventricular APD at 2 and 5 weeks CAVB, leading to an increase in spatial dispersion. At that time torsade de pointes were evocable in the majority of the dogs. Hypertrophy had only developed completely at 5 weeks CAVB. Irbesartan had no effect on electrical and structural parameters or on arrhythmogenicity., Conclusions: In the CAVB dog ventricular hypertrophy is not a prerequisite for electrical remodeling or drug-induced torsade de pointes, and the AT1-receptor has no dominant role in the completion of these remodeling processes.

Background: In large mammals and humans, the contribution of IKs to ventricular repolarization is still incompletely understood., Methods and Results: In vivo and cellular electrophysiological experiments were conducted to study IKs in canine ventricular repolarization. In conscious dogs, administration of the selective IKs blocker HMR 1556 (3, 10, or 30 mg/kg PO) caused substantial dose-dependent QT prolongations with broad-based T waves. In isolated ventricular myocytes under baseline conditions, however, IKs block (chromanols HMR 1556 and 293B) did not significantly prolong action potential duration (APD) at fast or slow steady-state pacing rates. This was because of the limited activation of IKs in the voltage and time domains of the AP, although at seconds-long depolarizations, the current was substantial. Isoproterenol increased and accelerated IKs activation to promote APD95 shortening. This shortening was importantly reversed by HMR 1556 and 293B. Quantitatively similar effects were obtained in ventricular-tissue preparations. Finally, when cellular repolarization was impaired by IKr block, IKs block exaggerated repolarization instability with further prolongation of APD., Conclusions: Ventricular repolarization in conscious dogs is importantly dependent on IKs. IKs function becomes prominent during beta-adrenergic receptor stimulation, when it promotes AP shortening by increased activation, and during IKr block, when it limits repolarization instability by time-dependent activation. Unstimulated IKs does not contribute to cellular APD at baseline. These data highlight the importance of the synergism between an intact basal IKs and the sympathetic nervous system in vivo.

Unlabelled: Heterogeneity in cardiac repolarization (Delta APD) is known to be arrhythmic. In the dog model of chronic complete AV-block and acquired long QT syndrome, an increase in Delta MAPD (defined as left ventricular monophasic action potential duration (MAPD) minus right ventricular MAPD) is often associated with changes in T-wave morphology. The purpose of this study was to correlate known changes in Delta MAPD with the planimetric total area of the T-wave on the surface ECG (integral of J-T, mVx ms)., Methods: The relationship between Delta MAPD and total area of the T-wave (i.e., JT-area) was assessed in four different protocols with different types of dispersion: (1) class III drugs followed by levcromakalim (n= 7), (2) LAD coronary artery occlusion and reperfusion (n = 6), (3) dronedarone i.v., an amiodarone like agent (n = 5) and (4) steady state pacing at cycle lengths of 1000 ms and 500 ms (n = 5)., Results: Class III drugs increased Delta MAPD (55 +/- 40 ms to 120 +/- 50 ms(#), P<0.05), which was correlated (r = 0.74, P < 0.001) with JT-area (50 +/- 40 mV. ms to 95 +/- 35 mV x ms(#)). Ischemia increased both Delta MAPD (30 +/- 25 ms to 90 +/- 40 ms(#)) and JT-area (60 +/- 55 mV x ms to 75 +/- 50 mV x ms(#)). Both levcromakalim and reperfusion reversed these conditions. Dronedarone had no effect on Delta MAPD or on JT-area while a faster frequency reduced both Delta MAPD and JT-area., Conclusion: Changes in dispersion of ventricular repolarization are reflected by alterations in JT-area. This non-invasive parameter may therefore be used to indicate changes in heterogeneity in ventricular repolarization.

Background: Amiodarone is an effective antiarrhythmic drug rarely associated with torsade de pointes arrhythmias (TdP). The noniodinated compound dronedarone could resemble amiodarone and be devoid of the adverse effects. In the dog with chronic complete atrioventricular (AV) block (CAVB) and acquired long-QT syndrome, the electrophysiological and proarrhythmic properties of the drugs were compared after 4 weeks of oral treatment., Methods and Results: Amiodarone (n=7, 40 mg. kg(-1). d(-1)) and dronedarone (n=8, 20 mg/kg BID) were started at 6 weeks of CAVB (baseline). Six dogs served as controls. Surface ECGs and endocardially placed monophasic action potential catheters in the left (LV) and right (RV) ventricles were recorded to assess QTc time, action potential duration (APD), interventricular dispersion (DeltaAPD=LV APD minus RV APD), early afterdepolarizations (EADs), ectopic beats, and TdP. Both amiodarone (+21%) and dronedarone (+31%) increased QTc time. Amiodarone showed no increase in DeltaAPD in 4 of 7 dogs, whereas dronedarone augmented DeltaAPD in 7 of 8 animals. After dronedarone, TdP occurred in 4 of 8 dogs with the highest DeltaAPD (105+/-20 ms). TdP was never seen with amiodarone, not even in the dogs that had DeltaAPD values comparable to those with dronedarone. Furthermore, a difference existed in EADs and ectopic activity incidence (dronedarone 3 of 8; amiodarone 0 of 7), which was also seen during an epinephrine challenge., Conclusions: In the CAVB dog model, both amiodarone and dronedarone prolong QT time (class III effect). The absence of TdP with amiodarone seems to be related to homogeneous APD lengthening in the majority of dogs and the lack of EADs and/or ventricular ectopic beats in all.

When a new (cardiovascular) drug shows signs of QT interval prolongation on the ECG (delay in repolarization time), the regulatory agencies demand screening of its possible proarrhythmic potential before approving it for clinical practice. In this review, identified predisposing factors have been related to specific electrophysiological parameters, allowing quantification of their contribution to Torsade de Pointes arrhythmias. In addition, arrhythmogenic mechanisms involved in the initiation and perpetuation of drug-induced Torsade de Pointes are discussed.

Background: The dog model of chronic complete AV-block (CAVB) demonstrates a considerable incidence of (witnessed) sudden death (16/117 dogs). In this study we tried to: (1) elucidate the mechanisms of sudden death using an ECG telemetry device and (2) identify retrospectively the risk parameters indicative of this arrhythmogenic death., Methods: Between 1994 and 1998, 78 anesthetized dogs underwent an extensive electrophysiological study including: (1) left- (LV) and right ventricular (RV) monophasic action potential (MAP) recordings to assess Delta MAPD (LV APD minus RV APD) and (2) pacing protocols (PES) to induce torsade de pointes arrhythmias (TdP) at 4--6 weeks CAVB. Eight animals experienced sudden cardiac death (SCD) during the follow-up period (mean 7+/-3 weeks CAVB). Since the response of the CAVB dog to class III drugs is not uniform we also made comparisons among the SCD group, TdP drug responders and non-responders. For this purpose we selected all animals which (1) received almokalant (n=15, 0.12 mg/kg/5 min) or ibutilide (n=9, 0.025 mg/kg/5 min) as an additional challenge to induce TdP and (2) had a follow-up period of at least 4 weeks., Results: Six out of eight SCD dogs showed inducible TdP at baseline. Two of eight dogs had telemetric ECG surveillance and both revealed polymorphic VT as the cause of SCD. Baseline Delta MAPD of the SCD (90+/-15 ms) was significantly higher than the non-SCD group (n=70, 60+/-30 ms). Of the 24 dogs which received class III drugs, 12 belonged to the TdP responder group. Delta MAPD of the TdP responder group (80+/-15 ms) was similar to the SCD group and significantly higher compared to the non-responder group (n=12, 40+/-25 ms). QT-time and cycle length of idioventricular rhythm were not different., Conclusion: In the CAVB dog model, SCD is (1) most probably related to TdP while (2) inducible TdP and the measure of Delta MAPD at baseline indicate susceptibility to SCD.

Torsade de Pointes arrhythmias are a feared proarrhythmic effect of (antiarrhythmic) drugs. In dogs with chronic complete AV-block bradycardia-induced volume overload leads to electrical remodeling, which includes increased susceptibility to drug-induced Torsade de Pointes arrhythmias. The IKr channel blocker, dofetilide (Tikosyn, 0.025 mg/kg/5 min), and the less specific ion channel blocker, azimilide (5 mg/kg/5 min), were compared in nine anesthetized dogs at 4 and 6 weeks of AV-block in a randomized cross-over design. Dosages were based on our own dose-dependence studies and on anti-arrhythmic dosages reported in the literature. Monophasic action potential catheters were placed endocardially in both the left and right ventricle to measure action potential duration, visualize early afterdepolarizations, and to assess interventricular dispersion of repolarization (i.e. left ventricular monophasic action potential duration (at 100%) minus right ventricular monophasic action potential duration (at 100%). Cycle length of idioventricular rhythm, QT-time and the occurrence of drug-induced Torsade de Pointes arrhythmias were determined using the surface electrocardiogram (ECG). Before drug administration, the electrophysiological parameters were identical at 4 and 6 weeks. Both azimilide and dofetilide increased monophasic action potential duration, cycle length of idioventricular rhythm, and QT-time. Dissimilar lengthening of left ventricular and right ventricular monophasic action potential duration increased the interventricular dispersion significantly from 55 to 110 ms for both drugs. All dogs had early afterdepolarizations, while, in the majority, ectopic ventricular beats developed (dofetilide 8/9 and azimilide 7/9). Torsade de Pointes arrhythmias incidence was comparable for dofetilide (6/9) and azimilide (5/9). In conclusion, azimilide and dofetilide show similar electrophysiological and proarrhythmic effects in our canine model with a high incidence of Torsade de Pointes arrhythmias.