Kevin A. Michael

Cardiac resynchronization therapy for the treatment of sleep apnoea: a meta-analysis

AIMS Sleep apnoea (SA) is a common problem among congestive heart failure (CHF) patients. Evidence has shown that cardiac resynchronization therapy (CRT) reduces morbidity and mortality associated with CHF. The aim of this paper was to review studies evaluating the reduction of the Apnoea-Hypopnoea Index (AHI) in patients with SA after treatment with CRT and to perform a meta-analysis to estimate the true effect of CRT on SA. METHODS AND RESULTS A systematic electronic literature search was conducted in Medline and Embase to identify studies reporting on the effects of CRT on SA. A hand search of five major cardiology societies was performed to identify any unpublished studies through structured abstracts submitted to conference proceedings. To be eligible for inclusion, studies had to include a comparison of CRT vs. no pacing and use AHI as an outcome. Non-English studies were excluded. Nine manuscripts and five abstracts were identified for review. Six manuscripts and three abstracts were included in meta-analysis, which included 170 patients. After treatment with CRT, a significant reduction in AHI was found in patients with central sleep apnoea (CSA) with a mean reduction of -13.05 (CI -16.74 to -9.36; P < 0.00001) but not in patients with obstructive sleep apnoea (13.32; CI -9.04 to 2.39; P = 0.25). CONCLUSION Cardiac resynchronization therapy reduces the severity of SA. Major effects are seen in patients with CSA. The presence of SA may be an additional consideration when deciding on which heart failure patients will receive CRT.

New-onset atrial fibrillation after cavotricuspid isthmus ablation: identification of advanced interatrial block is key

AIMS A significant proportion of patients develop atrial fibrillation (AF) following cavotricuspid isthmus (CTI) ablation for typical atrial flutter (AFl). The objective of this study was to assess whether the presence of advanced interatrial block (aIAB) was associated with an elevated risk of AF after CTI ablation in patients with typical AFl and no prior history of AF. METHODS AND RESULTS This study included patients with typical AFl and no prior history of AF that were referred for CTI ablation. Patients were excluded when they had received repeat ablations or did not demonstrate a bidirectional block. In all patients, a post-ablation electrocardiogram (ECG) in sinus rhythm was evaluated for the presence of aIAB, defined as a P-wave duration ≥120 ms and biphasic morphology in the inferior leads. New-onset AF was identified from 12-lead ECGs, Holter monitoring, and device interrogations. The cohort comprised 187 patients (age 67 ± 10.7 years; ejection fraction 55.8 ± 11.2%). Advanced interatrial block was detected in 18.2% of patients, and left atrium was larger in patients with aIAB compared with those without aIAB (46.2 ± 5.9 vs. 43.1 ± 6.0 mm; P = 0.01). Over a median follow-up of 24.2 months, 67 patients (35.8%) developed new-onset AF. The incidence of new-onset AF was greater in patients with aIAB compared with those without aIAB (64.7 vs. 29.4%; P < 0.001). After a comprehensive multivariate analysis, aIAB emerged as the strongest predictor of new-onset AF [odds ratio (OR) 4.2, 95% confidence interval (CI): 1.9-9.3; P < 0.001]. CONCLUSION Advanced interatrial block is a key predictor for high risk of new-onset AF after a successful CTI ablation in patients with typical AFl.

Advanced Interatrial Block Predicts New Onset Atrial Fibrillation in Patients with Severe Heart Failure and Cardiac Resynchronization Therapy

Advanced interatrial block (aIAB) on the surface electrocardiogram (ECG), defined as a P‐wave duration ≥120 milliseconds with biphasic (±) morphology in inferior leads, is frequently associated with atrial fibrillation (AF). The aim of this study was to determine whether preoperative aIAB could predict new‐onset AF in patients with severe congestive heart failure (CHF) requiring cardiac resynchronization therapy (CRT).

Obstructive Sleep Apnea as a Predictor of Atrial Fibrillation After Coronary Artery Bypass Grafting: A Systematic Review and Meta-analysis

BACKGROUND Post-coronary artery bypass grafting atrial fibrillation (PCAF) is associated with increased morbidity, mortality, and system costs. Few studies have explored obstructive sleep apnea (OSA) as a risk factor for PCAF. We aimed to systematically review and synthesize the evidence associating OSA with PCAF. METHODS We conducted a search of MEDLINE, EMBASE, Google Scholar, and Web of Science, as well as abstracts, conference proceedings, and reference lists until June 2014. Eligible studies were in English, were conducted in humans, and assessed OSA with polysomnography (PSG) or a validated questionnaire. Two reviewers independently selected studies, with disagreement resolved by consensus. Piloted forms were used to extract data and assess risk of bias. RESULTS Five prospective cohort studies were included (n = 642). There was agreement in study selection (κ statistic, 0.89; 95% confidence interval [CI], 0.75-1.00). OSA was associated with a higher risk of PCAF (odds ratio [OR], 1.86; 95% CI 1.24-2.80; P = 0.003; I(2) = 35%). We conducted 3 subgroup analyses. The associations increased for data that used PSG to assess OSA (OR, 2.34; 95% CI, 1.48-3.70), when severe OSA was included from 1 study (OR, 2.59; 95% CI, 1.63-4.11), and when adjusted analyses were pooled (OR, 2.38; 95% CI, 1.57-3.62; P < 0.001 in all), with no heterogeneity detected in any subgroup analysis (I(2) < 0.01% in all). CONCLUSIONS OSA was shown to be a strong predictor of PCAF.

Maximal Electric Separation–Guided Placement of Right Ventricular Lead Improves Responders in Cardiac Resynchronization Defibrillator Therapy

Background—Cardiac resynchronization therapy is widely used for the treatment of heart failure. Recent data suggest that electric separation during left ventricular pacing varies within the right ventricle (RV). We hypothesized that placement of the RV lead guided by maximal electric separation (MES) would improve response to cardiac resynchronization therapy compared with standard apical placement. Methods and Results—A single-blind, randomized controlled trial was conducted. Patients eligible for cardiac resynchronization therapy-D were enrolled. Left ventricular lead placement was performed at the coronary sinus branch. The RV outflow tract, septum, and apex were mapped during left ventricular pacing and MES recorded. Patients were randomized to receive either apical placement or RV lead placement at the site mapping MES. Left ventricular ejection fraction, 6-minute walk distance, and New York Heart Association functional class were recorded at baseline and 3 months by blinded observers. Response was defined as at least one of the following: 5% absolute increase in ejection fraction, 50 m increase in 6-minute walk distance, or an increase by >1 functional class. Primary end point was improvement in ejection fraction at 3 months. Fifty patients were randomized (25 MES-guided and 25 apical). Baseline characteristics were similar in the 2 groups. Electric separation was lower in the apex (143±23 versus 168±25 ms in MES group; P=0.01). MES was most commonly septal and rarely apical (4/50 patients). Responders in the MES-guided versus apical group are as follows: Echo 21 versus 13 patients (P=0.032), 6-minute walk distance 19 versus 12 patients (P=0.079), and functional class 22 versus 15 patients (P=0.051). No dislodgment or reposition for suboptimal defibrillation tests was reported. Conclusions—MES-guided placement of the RV lead improves cardiac resynchronization therapy responders compared with standard apical placement.

Radiofrequency Catheter Ablation for the Treatment of Idiopathic Premature Ventricular Contractions Originating from the Right Ventricular Outflow Tract: A Systematic Review and Meta‐Analysis

Frequent idiopathic premature ventricular contractions (PVCs) have been associated with left ventricular cardiomyopathy. Idiopathic PVCs often originate from the right ventricular outflow tract (RVOT), and radiofrequency catheter ablation (RFCA) is being used as a treatment to alleviate symptoms. A meta‐analysis was performed to evaluate RFCA for the treatment of frequent idiopathic PVCs on heart function.

Transesophageal echocardiography for the prevention of embolic complications after catheter ablation for atrial fibrillation.

Background: Thromboembolic complications during left‐sided ablations range between 1.5 and 5.4%. Preprocedural TEE has been used to exclude the presence of left atrial thrombi in order to minimize risk. The use of TEE is empiric and it has not been evaluated in contemporary practice.

The Right Ventricular Septum Presents the Optimum Site for Maximal Electrical Separation During Left Ventricular Pacing

Septum Presents the Optimum Site for Maximal Electrical Separation.

Superior approach for radiofrequency ablation of atrio-ventricular nodal reentrant tachycardia in a patient with anomalous inferior vena cava and azygos continuation.

We present a 45-year-old woman with supraventricular tachycardia. During placement of diagnostic catheters, an interruption of the inferior vena cava was suspected. An MRI confirmed the interruption of the inferior vena cava above the level of the renal veins with azygos vein continuation up to the superior vena cava. Catheter ablation was performed using a superior approach via the left subclavian vein.

Cardiac Rhythm Device Contact Dermatitis

We present a series of three cases of patch testing confirmed cardiac rhythm device induced contact dermatitis. In the first two cases, there was complete resolution with device extraction and reimplantation with another device with either an absence of the offending agent or a coating with another resin or metal. These cases illustrate the difficulties in diagnosing pain, tenderness, and dermatological manifestations in patients with cardiac rhythm devices (pacemakers and implantable cardioverter defibrillators)