An overview of heart rhythm disorders and management in myotonic dystrophy type 1.

Myotonic dystrophy type 1 (DM1) is the most common adult form of muscular dystrophy, presenting with a constellation of systemic findings secondary to a CTG triplet expansion of the noncoding region of the DMPK gene. Cardiac involvement is frequent, with conduction disease and supraventricular and ventricular arrhythmias being the most prevalent cardiac manifestations, often developing from a young age. The development of cardiac arrhythmias has been linked to increased morbidity and mortality, with sudden cardiac death well described. Strategies to mitigate risk of arrhythmic death have been developed. In this review, we outline the current knowledge on the pathophysiology of rhythm abnormalities in patients with myotonic dystrophy and summarize available knowledge on arrhythmic risk stratification. We also review management strategies from an electrophysiological perspective, attempting to underline the substantial unmet need to address residual arrhythmic risks for this population.

Ethanol ablation for ventricular arrhythmias: A systematic review and meta-analysis.

INTRODUCTION: Ethanol ablation (EA) is an alternative option for subjects with ventricular arrhythmias (VAs) refractory to conventional medical and ablative treatment. However, data on the efficacy and safety of EA remain sparse. METHODS: A systematic literature search was conducted. The primary outcomes were 1) freedom from the targeted VA and 2) freedom from any VAs post-EA. Additional safety outcomes were also analyzed. RESULTS: Ten studies were selected accounting for a population of 174 patients (62.3 ± 12.5 years, 94% male) undergoing 185 procedures. The overall acute success rate of EA was 72.4% (confidence interval [CI95% ]: 65.6-78.4). After a mean follow-up of 11.3 ± 5.5 months, the incidence of relapse of the targeted VA was 24.4% (CI95% : 17.1-32.8), while any VAs post-EA occurred in 41.3% (CI95% : 33.7-49.1). The overall incidence of procedural complications was 14.1% (CI95% : 9.8-19.8), with pericardial complications and complete atrioventricular block being the most frequent. An anterograde transarterial approach was associated with a higher rate of VA recurrences and complications compared to a retrograde transvenous route; however, differences in the baseline population characteristics and in the targeted ventricular areas should be accounted. CONCLUSION: EA is a valuable therapeutic option for VAs refractory to conventional treatment and can result in 1-year freedom from VA recurrence in 60%-75% of the patients. However, anatomical or technical challenges preclude acute success in almost 30% of the candidates and the rate of complication is not insignificant, highlighting the importance of well-informed patient selection. The certainty of the evidence is low, and further research is necessary.

A Normal Electrocardiogram Does Not Exclude Infra-Hisian Conduction Disease in Patients With Myotonic Dystrophy Type 1.

OBJECTIVES: This study aimed to identify electrocardiographic (ECG) predictors of a prolonged His-ventricular (HV) interval in patients with type 1 myotonic dystrophy (DM1). BACKGROUND: Patients with DM1 have an increased risk of sudden cardiac death. The presence of His-Purkinje system disease/prolonged HV interval (≥70 ms) is associated with a higher risk of potentially life-threatening bradyarrhythmic events. METHODS: Electrophysiology studies (EPSs) were performed in all DM1 patients referred to 2 tertiary centers for routine cardiac assessment. In a subgroup of patients, the EPS was repeated at varying intervals. RESULTS: A total of 154 patients (mean age: 43.7 ± 13.3; 58.1% male) underwent 202 diagnostic EPSs. HV ≥70 ms was found on 58 EPSs (28.7%); 9 of 59 patients (15.2%) with PR <200 ms and QRS interval <110 ms on baseline ECG had an HV ≥70 ms on EPS. Among those with PR ≥200 ms and/or QRS interval ≥100 ms, only 33.9% had an HV ≥70 ms on EPS. There were 38 patients who underwent repeated EPS, in which 28.8% demonstrated a prolongation of the HV interval overall compared with baseline. QRS duration demonstrated the most powerful discriminative capacity for HV ≥70 ms (area under the receiver operating characteristic curve: 0.76; 95% confidence interval [CI]: 0.68 to 0.84; p < 0.001). On multivariate analysis, QRS interval ≥112 ms had the highest predictive value for HV ≥70 ms (odds ratio: 7.94; 95% CI: 3.85 to 16.37. CONCLUSIONS: ECG parameters have a poor predictive value for infra-Hisian conduction block in DM1 patients. QRS and PR intervals are normal in up to 15.2% of DM1 patients with prolonged HV, and 66.1% of those with PR ≥200 ms and/or QRS ≥100 ms do not have advanced His-Purkinje conduction system disease on EPS. Electrophysiology testing should be a mandatory part of screening for all patients to guide prophylactic pacemaker implantation.

Post-operative cardiac implantable electronic devices in patients undergoing cardiac surgery: a contemporary experience.

AIMS: Optimum timing of pacemaker implantation following cardiac surgery is a clinical challenge. European and American guidelines recommend observation, to assess recovery of atrioventricular block (AVB) (up to 7 days) and sinus node (5 days to weeks) after cardiac surgery. This study aims to determine rates of cardiac implantable electronic devices (CIEDs) implants post-surgery at a high-volume tertiary centre over 3 years. Implant timing, patient characteristics and outcomes at 6 months including pacemaker utilization were assessed. METHODS AND RESULTS: All cardiac operations (n = 5950) were screened for CIED implantation following surgery, during the same admission, from 2015 to 2018. Data collection included patient, operative, and device characteristics; pacing utilization and complications at 6 months. A total of 250 (4.2%) implants occurred; 232 (3.9%) for bradycardia. Advanced age, infective endocarditis, left ventricle systolic impairment, and valve surgery were independent predictors for CIED implants (P < 0.0001). Relative risk (RR) of CIED implants and proportion of AVB increased with valve numbers operated (single-triple) vs. non-valve surgery: RR 5.4 (95% CI 3.9-7.6)-21.0 (11.4-38.9) CIEDs. Follow-up pacing utilization data were available in 91%. Significant utilization occurred in 82% and underutilization (<1% A and V paced) in 18%. There were no significant differences comparing utilization rates in early (≤day 5 post-operatively) vs. late implants (P = 0.55). CONCLUSION: Multi-valve surgery has a particularly high incidence of CIED implants (14.9% double, 25.6% triple valve). Age, left ventricle systolic impairment, endocarditis, and valve surgery were independent predictors of CIED implants. Device underutilization was infrequent and uninfluenced by implant timing. Early implantation (≤5 days) should be considered in AVB post-multi-valve surgery.

Effect of tricuspid regurgitation and right ventricular dysfunction on long-term mortality in patients undergoing cardiac devices implantation: >10-year follow-up study.

BACKGROUND: The long-term effect of tricuspid regurgitation (TR) after device implantation on long-term mortality remains unknown. In the present study, we sought to examine whether patients undergoing an implantable cardiac device procedure (pacemaker, cardiac defibrillator or cardiac resynchronisation therapy) have an increased risk of TR and to determine the effect of this on long-term survival. METHODS: A total of 304 patients who underwent device implant and had pre- and post-implant transthoracic echocardiogram were included in the analysis. All-cause mortality was the study endpoint over a follow-up period of median 11.6 years. RESULTS: New ≥ moderate tricuspid regurgitation post-device implantation developed in 66/304 (21.7%) patients. New right ventricular dysfunction post-device implantation occurred in 59/304 (19.4%) patients. Independent predictors of new RV dysfunction were ischaemic heart disease (OR 4.23, 95% CI 1.58 - 11.33, p = 0.004), left ventricular impairment (OR 2.74, 95% CI 5.41 - 30.00, p < 0.0001) and new ≥ moderate TR (OR 7.72, 95% CI 3.27 - 18.23, p < 0.001). Independent predictors of mortality were new ≥ moderate TR [HR: 3.14 (95% CI 1.29 - 7.63) p = 0.01] and new RV impairment [HR: 2.82 (95% CI 1.33 - 5.98) p = 0.01. CONCLUSIONS: Worsening TR and RV dysfunction post-device implantation is common. New post-implant ≥ moderate TR is associated with increased risk of new RV impairment and poor long term (>10 years) survival.

Full blood count as potential predictor of outcomes in patients undergoing cardiac resynchronization therapy.

Almost a third of patients fulfilling current guidelines criteria have suboptimal responses following cardiac resynchronization therapy (CRT). Circulating biomarkers may help identify these patients. We aimed to assess the predictive role of full blood count (FBC) parameters in prognosis of heart failure (HF) patients undergoing CRT device implantation. We enrolled 612 consecutive CRT patients and FBC was measured within 24 hours prior to implantation. The follow-up period was a median of 1652 days (IQR: 837-2612). The study endpoints were i) composite of all-cause mortality or transplant, and ii) reverse left ventricular (LV) remodeling. On multivariate analysis [hazard ratio (HR), 95% confidence interval (CI)] only red cell count (RCC) (p = 0.004), red cell distribution width (RDW) (p < 0.001), percentage of lymphocytes (p = 0.03) and platelet count (p < 0.001) predicted all-cause mortality. Interestingly, RDW (p = 0.004) and platelet count (p = 0.008) were independent predictors of reverse LV remodeling. This is the first powered single-centre study to demonstrate that RDW and platelet count are independent predictors of long-term all-cause mortality and/or heart transplant in CRT patients. Further studies, on the role of these parameters in enhancing patient selection for CRT implantation should be conducted to confirm our findings.

The use of a single chamber leadless pacemaker for the treatment of cardioinhibitory vasovagal syncope.

BACKGROUND: The use of pacemakers in the treatment of cardioinhibitory vasovagal syncope is controversial with a mixed message from the limited evidence base. Single chamber leadless pacemakers have been shown to be an effective alternative option to conventional pacemakers. OBJECTIVE: This study examines the use of leadless pacemakers in a cardioinhibitory vasovagal population in the United Kingdom. METHODS: Observational data on 32 patients implanted with the Micra Transcatheter Pacemaker System for vasovagal syncope are presented. Data was collected on implant indications, implant procedure and follow up data from 12 centres across the United Kingdom that had elected to use a Micra leadless pacemaker in this patient population. RESULTS: 32 patients aged 37 ±â€¯14 years (range 18 to 64 years) with 62% of the patients being female were recruited to the study. Vasovagal syncope was diagnosed clinically and with the support of Holter monitoring, tilt table testing and implantable loop recorders. The duration of symptoms was 8 ±â€¯8 yrs. with an average frequency of syncope being 4 ±â€¯6 times/year. The Micra pacemaker was successfully implanted in all patients with a major complication rate of 3.1%. Patients were followed up for 404 ±â€¯237 days (range 63-928 days). At follow up 28 (87%) patients were free from symptoms. CONCLUSIONS: This observational study suggests that the use of a single chamber leadless pacemaker in the treatment of cardioinhibitory vasovagal syncope might be a reasonable clinical option.

Catheter ablation for fascicular ventricular tachycardia: A systematic review.

INTRODUCTION: Catheter ablation has been evaluated as treatment for fascicular ventricular tachycardia (FVT) in several single-centre cohort studies, with variable results regarding efficacy and outcomes. METHODS: A systematic search was performed on PubMed, EMBASE and Cochrane database (from inception to November 2017) that included studies on FVT catheter ablation. RESULTS: Thirty-eight observational non-controlled case series comprising 953 patients with FVT undergoing catheter ablation were identified. Three studies were prospective and only 5 were multi-centre. Eight-hundred and eighty-four patients (94.2%) had left posterior FVT, 25 (3.4%) left anterior FVT and 30 (2.4%) other forms. In 331 patients (41%), ablation was performed in sinus rhythm (SR). The mean follow-up period was 41.4 ±â€¯10.7 months. Relapse of FVT occurred in 100 patients (10.7%). Among the 79 patients (8.3%) requiring a further procedure after the index ablation, 19 (2%) had further FVT relapses. Studies in which ablation was performed in FVT had similar success rate after multiple procedures compared to ablation in SR only (95.1%, CI95% 92.2-97%, I2 = 0% versus 94.8%, CI95% 87.6-97.9%, I2 = 0%, respectively). Success rate was numerically lower in paediatric-only series compared to non-paediatric cases (90.0%, CI95% 82.1-94.6%, I2 = 0% versus 94.3%, CI95% 92.2-95.9%, I2 = 0%, respectively). CONCLUSION: Data derived from observational non-controlled case series, with low-methodological quality, suggest that catheter ablation is a safe and effective treatment for FVT, with a 93.5% success rate after multiple procedures. Ablation during FVT represents the first-line and most commonly used approach; however, a strategy of mapping and ablation during SR displayed comparable procedural results to actively mapping patients in FVT and should therefore be considered in selected cases where FVT is not inducible.

Differences in the upslope of the precordial body surface ECG T wave reflect right to left dispersion of repolarization in the intact human heart.

BACKGROUND: The relationship between the surface electrocardiogram (ECG) T wave to intracardiac repolarization is poorly understood. OBJECTIVE: The purpose of this study was to examine the association between intracardiac ventricular repolarization and the T wave on the body surface ECG (SECGTW). METHODS: Ten patients with a normal heart (age 35 ± 15 years; 6 men) were studied. Decapolar electrophysiological catheters were placed in the right ventricle (RV) and lateral left ventricle (LV) to record in an apicobasal orientation and in the lateral LV branch of the coronary sinus (CS) for transmural recording. Each catheter (CS, LV, RV) was sequentially paced using an S1-S2 restitution protocol. Intracardiac repolarization time and apicobasal, RV-LV, and transmural repolarization dispersion were correlated with the SECGTW, and a total of 23,946 T waves analyzed. RESULTS: RV endocardial repolarization occurred on the upslope of lead V1, V2, and V3 SECGTW, with sensitivity of 0.89, 0.91, and 0.84 and specificity of 0.67, 0.68, and 0.65, respectively. LV basal endocardial, epicardial, and mid-endocardial repolarization occurred on the upslope of leads V6 and I, with sensitivity of 0.79 and 0.8 and specificity of 0.66 and 0.67, respectively. Differences between the end of the upslope in V1, V2, and V3 vs V6 strongly correlated with right to left dispersion of repolarization (intraclass correlation coefficient 0.81, 0.83, and 0.85, respectively; P <.001). Poor association between the T wave and apicobasal and transmural dispersion of repolarization was seen. CONCLUSION: The precordial SECGTW reflects regional repolarization differences between right and left heart. These findings have important implications for accurately identifying biomarkers of arrhythmogenic risk in disease.

Procedural and quality assessment data on catheter ablation for fascicular ventricular tachycardia.

Data presented in this article are supplementary materials to our article entitled "Catheter Ablation for Fascicular Ventricular Tachycardia: A Systematic review" (Creta et al., 2018). The current article provides additional procedural data regarding the catheter ablation for fascicular ventricular tachycardia (FVT) performed in the patients enrolled in our analysis. Furthermore, we provide data regarding the quality assessment of the studies included in our systematic review.

Usefulness of a clinical risk score to predict the response to cardiac resynchronization therapy.

BACKGROUND: Almost 1/3 of heart failure patients fail to respond to cardiac resynchronization therapy (CRT). A simple clinical score to predict who these patients are at the moment of referral or at time of implant may be of importance for early optimization of their management. METHODS: Observational study. A risk score was derived from factors associated to CRT response. The derivation cohort was composed of 1301 patients implanted with a CRT defibrillator in a multi-center French cohort-study. External validation of this score and assessment of its association with CRT response and all-cause mortality and/or heart transplant was performed in 1959 CRT patients implanted in 4 high-volume European centers. RESULTS: Independent predictors of CRT response in the derivation cohort were: female gender (OR = 2.08, 95% CI 1.26-3.45), NYHA class ≤ III (OR = 2.71, 95% CI 1.63-4.52), left ventricular ejection fraction ≥ 25% (OR = 1.75, 95% CI 1.27-2.41), QRS duration ≥ 150 ms (OR = 1.70, 95% CI 1.25-2.30) and estimated glomerular filtration rate ≥ 60 mL/min (OR = 2.01, 95% CI 1.48-2.72). Each was assigned 1 point. External validation showed good calibration (Hosmer-Lemeshow test-P = 0.95), accuracy (Brier score = 0.19) and discrimination (c-statistic = 0.67), with CRT response increasing progressively from 37.5% in patients with a score of 0 to 91.9% among those with score of 5 (Gamma for trend = 0.44, P < 0.001). Similar results were observed regarding all-cause mortality or heart transplant. CONCLUSION: The ScREEN score (Sex category, Renal function, ECG/QRS width, Ejection fraction and NYHA class) is composed of widely validated, easy to obtain predictors of CRT response, and predicts CRT response and overall mortality. It should be helpful in facilitating early consideration of alternative therapies for predicted non-responders to CRT therapy.

Empowerment of athletes with cardiac disorders: a new paradigm.

Athletes with cardiac disorders frequently pose an ethical and medical dilemma to physicians assessing their eligibility to participate in sport. In recent decades, patient empowerment has been gaining increasing recognition in clinical decision-making. Empowerment is a process through which people are involved over the decisions and actions that affect their own lives. In the context of a cardiac disorder, empowerment means giving an athlete the chance to participate in the decision about whether or not to remain active in competition. Three models of treatment decision-making are described in this article, with progressive levels of empowerment: the paternalistic model (the athlete has a passive role), the shared-decision making model (both athlete and physician participate in the decision), and the informed-decision making (the decision is made by the athlete while the role of the physician is solely to provide information). This article critically discusses the issues involved in disqualification of athletes with cardiovascular disorders and suggests possible ways of incorporating patient empowerment in potentially career-ending decisions. The authors propose a model of empowerment, which gives patients the opportunity to choose how much, and if, they would like to be involved in the decision-making process.

Call for joint informed consent in athletes with inherited cardiac conditions.

Informed consent is of the utmost importance, especially in complex clinical situations where patients may be exposed to a life-threatening risk. A particularly complex example is the eligibility of competitive athletes with inherited cardiac conditions on medical grounds, especially when the risk is low or unquantifiable. The rationale and benefits of a joint informed consent for athletes to compete with potentially life-threatening cardiac conditions are discussed in this manuscript.

Dual-site right ventricular pacing in patients undergoing cardiac resynchronization therapy: Results of a multicenter propensity-matched analysis.

BACKGROUND: Dual-site right ventricular pacing (Dual RV) has been proposed as an alternative for patients with heart failure undergoing cardiac resynchronization therapy (CRT) with a failure to deliver a coronary sinus (CS) lead. Only short-term hemodynamic and echocardiographic results of Dual RV are available. We aimed to assess the long-term results of Dual RV and its impact on survival. METHODS: Multicenter retrospective assessment of all CRT implants during a 12-year period. Patients with failed CS lead implantation, treated with Dual RV, were followed and assessed for the primary endpoint of all-cause mortality and/or heart transplant. A control group was obtained from contemporary patients using propensity matching for all available baseline variables. RESULTS: Ninety-three patients were implanted with Dual RV devices and compared with 93 matched controls. During a median of 1,273 days (interquartile range 557-2,218), intention-to-treat analysis showed that all-cause mortality and/or heart transplant was higher in the Dual RV group (adjusted hazard ratio [HR] = 1.66, 95% confidence interval [CI] 1.12-2.47, P = 0.012). As-treated analysis yielded similar results (HR = 1.97, 95% CI 1.31-2.96, P = 0.001). Cardiac device-related infections occurred seven times more frequently in the Dual RV site group (HR = 7.60, 95% CI 1.51-38.33, P = 0.014). Among Dual RV nonresponders, four had their apical leads switched off, five required an epicardial LV lead insertion, a transseptal LV lead was implanted in two, and in nine patients, after reviewing the CS venogram, a new CS lead insertion was successfully attempted. CONCLUSION: Dual RV pacing is associated with worse clinical outcomes and higher complication rates than conventional CRT.

Percutaneous left atrial appendage occlusion using different technologies in the United Kingdom: A multicenter registry.

OBJECTIVES: This study aimed at assessing the feasibility and long-term efficacy of left atrial appendage occlusion (LAAO) in a "real world" setting. BACKGROUND: Although LAAO has recently emerged as an alternative to oral anticoagulants in patients with atrial fibrillation for the prevention of thromboembolic stroke, "real world" data about the procedure with different devices are lacking. METHODS: Eight centers in the United Kingdom contributed to a retrospective registry for LAAO procedures undertaken between July 2009 and November 2014. RESULTS: A total of 371 patients (72.9 ± 8.3 years old, 88.9% males) were enrolled. The overall procedure success was 92.5%, with major events in 3.5% of cases. The device choice was Watchman in 63% of cases, Amplatzer Cardiac Plug in 34.7%, Lariat in 1.7%, and Coherex WaveCrest in 0.6%. A significant improvement in procedure success (from 89.2% to 95.7%; P = 0.018) and reduction of acute major complications (from 6.5% to 0.5%; P = 0.001) were observed between procedures in the first and the second half of the recruitment time. An annual 90.1% relative risk reduction (RRR) for ischemic stroke, an 87.2% thromboembolic events RRR, and a 92.9% major bleeding RRR were observed, if compared with the predicted annual risks based on CHADS2, CHA2DS2-Vasc, and HAS-BLED scores, respectively, over a follow-up period of 24.7 ± 16.07 months. CONCLUSIONS: LAAO can be performed safely in a real world setting with good implant success rates and procedural outcomes. The long-term benefits of the procedure are reassuring in terms of both ischemic events and avoidance of severe bleeding associated with anticoagulation in this patient group. © 2016 Wiley Periodicals, Inc.

Adenosine-guided pulmonary vein isolation versus conventional pulmonary vein isolation in patients undergoing atrial fibrillation ablation: An updated meta-analysis.

BACKGROUND: Recurrent atrial fibrillation episodes following pulmonary vein isolation (PVI) are frequently due to reconnection of PVs. Adenosine can unmask dormant conduction, leading to additional ablation to improve AF-free survival. We performed a meta-analysis of the literature to assess the role of adenosine testing in patients undergoing atrial fibrillation (AF) ablation. METHODS: PubMed, EMBASE, and Cochrane databases were searched through until December 2015 for studies reporting on the role of adenosine guided-PVI versus conventional PVI in AF ablation. RESULTS: Eleven studies including 4099 patients undergoing AF ablation were identified to assess the impact of adenosine testing. Mean age of the population was 61±3years: 25% female, 70% with paroxysmal AF. Follow up period of 12.5±5.1months. A significant benefit was observed in the studies published before 2013 (OR=1.75; 95%CI 1.32-2.33, p<0.001, I2=11%), retrospective (OR=2.05; 95%CI 1.47-2.86, p<0.001, I2=0%) and single-centre studies (OR=1.58; 95%CI 1.19-2.10, p=0.002, I2=30%). However, analysis of studies published since 2013 (OR=1.41; 95% CI 0.87-2.29, p=0.17, I2=75%) does not support any benefit from an adenosine-guided strategy. Similar findings were observed by pooling prospective case-control (OR=1.39; 95%CI 0.93-2.07, p=0.11, I2=75%), and prospective randomized controlled studies (OR=1.62; 95%CI 0.81-3.24, p=0.17, I2=86%). Part of the observed high heterogeneity can be explained by parameters such as dormant PVs percentage, use of new technology, improvement of center/operator experience, patients' characteristics including gender, age, and AF type. CONCLUSIONS: Pooling of contemporary data from high quality prospective case-control & prospective randomized controlled studies fails to show the benefit of adenosine-guided strategy to improve AF ablation outcomes.

Ventricular Arrhythmia Burden in Patients With Heart Failure and Cardiac Resynchronization Devices: The Importance of Renal Function.

BACKGROUND: Chronic kidney disease (CKD) is a risk factor for arrhythmias in patients with heart failure (HF). However, the effects of CKD on ventricular arrhythmia (VA) burden in patients with cardiac resynchronization therapy and defibrillator (CRT-D) devices in a primary prevention setting are unknown. OBJECTIVE: To determine whether baseline CKD is associated with increased risk of VA in patients implanted with primary prevention CRT-D devices. METHODS AND RESULTS: In this retrospective study, 199 consecutive primary prevention CRT-D recipients (2005-2010) were stratified by estimated glomerular filtration rate (eGFR) levels prior to device implantation with 106 (53.2%) ≥CKD III (eGFR < 60 mL/min/1.73 m2 ) (CKD group). CKD group patients were significantly older (70.0 ± 10 years vs. 61.3 ± 12 years, P < 0.05) with higher prevalence of ischemic cardiomyopathy (56.2% vs. 40.2%, P < 0.05). Detected ventricular tachycardia (VT)/ventricular fibrillation (VF) episodes resulting in device therapy occurred significantly more frequently in the CKD group [40/106(37.8%)] than controls [24/93(25.8%)], (odd ratio [OR] = 1.74, 95% confidence interval [CI] = 1.01-3.2, P = 0.05). At 5-year follow-up, interval censored data analysis showed 41% VT/VF incidence in the CKD group compared to 24% incidence in controls (P < 0.05). Cox proportional hazards model identified CKD > III as the only predictor of sustained VA in this group (adjusted hazard ratio [HR] 2.92, CI = 1.39-6.1, P = 0.004). CONCLUSION: Baseline CKD is a strong independent risk factor for VA in primary prevention CRT-D recipients. Further understanding of the underlying arrhythmogenic mechanisms relating to CKD may be of interest to allow appropriate correction and prevention. Device programming in this cohort may need to reflect this increased risk.

Ventricular stimulus site influences dynamic dispersion of repolarization in the intact human heart.

The spatial variation in restitution properties in relation to varying stimulus site is poorly defined. This study aimed to investigate the effect of varying stimulus site on apicobasal and transmural activation time (AT), action potential duration (APD) and repolarization time (RT) during restitution studies in the intact human heart. Ten patients with structurally normal hearts, undergoing clinical electrophysiology studies, were enrolled. Decapolar catheters were placed apex to base in the endocardial right ventricle (RVendo) and left ventricle (LVendo), and an LV branch of the coronary sinus (LVepi) for transmural recording. S1-S2 restitution protocols were performed pacing RVendo apex, LVendo base, and LVepi base. Overall, 725 restitution curves were analyzed, 74% of slopes had a maximum slope of activation recovery interval (ARI) restitution (Smax) > 1 (P < 0.001); mean Smax = 1.76. APD was shorter in the LVepi compared with LVendo, regardless of pacing site (30-ms difference during RVendo pacing, 25-ms during LVendo, and 48-ms during LVepi; 50th quantile, P < 0.01). Basal LVepi pacing resulted in a significant transmural gradient of RT (77 ms, 50th quantile: P < 0.01), due to loss of negative transmural AT-APD coupling (mean slope 0.63 ± 0.3). No significant transmural gradient in RT was demonstrated during endocardial RV or LV pacing, with preserved negative transmural AT-APD coupling (mean slope -1.36 ± 1.9 and -0.71 ± 0.4, respectively). Steep ARI restitution slopes predominate in the normal ventricle and dynamic ARI; RT gradients exist that are modulated by the site of activation. Epicardial stimulation to initiate ventricular activation promotes significant transmural gradients of repolarization that could be proarrhythmic.

Catheter ablation for atrial fibrillation in hypertrophic cardiomyopathy: a systematic review and meta-analysis.

OBJECTIVE: Atrial fibrillation (AF) is common in hypertrophic cardiomyopathy (HCM) and is associated with a high risk of stroke. The efficacy and safety of catheter ablation in this setting is poorly characterised. We aimed to systematically review the existing literature and to perform a meta-analysis to determine the efficacy and safety of catheter ablation of AF in patients with HCM. METHODS: Random-effects meta-analysis of studies comparing HCM versus non-HCM controls. The outcomes of freedom from AF/atrial tachycardia, and acute procedure-related complications were assessed. Studies were searched on MEDLINE, EMBASE, COCHRANE and clinicaltrials.gov. RESULTS: Fourteen studies were considered eligible for the systematic review, of which five were included in the meta-analysis. Freedom from AF/atrial tachycardia relapse was higher in patients without HCM (after a single procedure: 38.7% HCM vs 49.8% controls, OR=2.25, 95% CI 1.09 to 4.64, p=0.03; after ≥1 procedure: 51.8% HCM vs 71.2% controls, OR=2.62, 95% CI 1.52 to 4.51, p=0.0006; I(2)=33% and 26%, respectively). Risk of procedure-related adverse events was low. Repeat procedures (mean difference=0.16, 95% CI 0.0 to 0.32, p=0.05, I(2)=53%) and antiarrhythmic drugs (OR=4.70, 95% CI 2.31 to 9.55, p<0.0001, I(2)=0%) are more frequently needed in patients with HCM to prevent arrhythmia relapse. Sensitivity analyses suggested that the outcome in patients with HCM with less dilated atria and paroxysmal AF may be more comparable to the general population. CONCLUSIONS: The observed complication rate of catheter ablation of AF in patients with HCM was low. Even though the risk of relapse is twofold higher, catheter ablation can be effective in patients with HCM and AF, particularly in patients with paroxysmal AF and smaller atria.