Accuracy of the pacemaker-mediated tachycardia algorithm in Boston Scientific devices.

INTRODUCTION: The incidence of pacemaker-mediated tachycardia (PMT) varies as a function of patient characteristics, device programming and algorithm specificities. We investigated the efficacy of the Boston Scientific algorithm by reviewing PMT episodes in a large device population. METHODS: In this multicenter study, we included 328 patients implanted with a Boston Scientific device: 157 non-dependent patients with RYTHMIQ™ activated (RYTHMIQ group), 76 patients with permanent AV-conduction disorder (AV-block group) and 95 Cardiac Resynchronization Therapy patients (CRT group). For each patient, we reviewed the last 10 remote monitoring-transmitted EGMs diagnosed as PMT. RESULTS: We analyzed 784 PMT episodes across 118 patients. In the RYTHMIQ group, the diagnosis of PMT was correct in most episodes (80%) of which 69% was directly related to the prolongation of the AV-delay associated with the RYTHMIQ algorithm. The usual triggers for PMT were also observed (PVC 16%, PAC 9%). The remainder of the episodes (20%) in RYTHMIQ patients and most episodes of AV-block (66%) and CRT patients (74%) were incorrectly diagnosed as PMT during sinus tachycardia at the maximal tracking rate. The inappropriate intervention of the algorithm during exercise causes non-conducted P-waves, loss of CRT (sustained in six patients) and may have been pro-arrhythmogenic in one patient (induction of ventricular tachycardia). CONCLUSION: Algorithms to minimize ventricular pacing can occasionally have unintended consequences such as PMT. The PMT algorithm in Boston Scientific devices is associated with a high rate of incorrect PMT diagnosis during exercise resulting in inappropriate therapy with non-conducted P-waves, loss of CRT and limited risk of pro-arrhythmic events.

The D-HCM score, a new diagnostic tool for distinguishing hypertrophic cardiomyopathy from hypertensive cardiopathy.

AIM: The diagnosis of hypertrophic cardiomyopathy (HCM) with moderate hypertrophy is challenging. Hypertensive heart disease (HHD) is the most common differential diagnosis that mimics the LVH of HCM. The aim of this study was to compare the QRS duration in HCM and HHD to create a novel diagnostic tool to identify primary HCM. METHODS AND RESULTS: We conducted an international retrospective multicentre study enrolling patients with true HCM and HHD. A total of 547 individuals with HCM and 139 with HHD were included. The median QRS duration was significantly shorter in HCM than in HHD (88 ms [80-94] vs. 98 ms [88-108]; P < 0.01). Multivariable logistic regression identified for the novel diagnostic HCM (D-HCM) score: absence of antihypertensive drugs (+2); family history of unexplained sudden death (+2); QRS duration [<95 ms] = +1; maximum wall thickness (mm) [≥17] = +1. A cumulative QRS-HCM score ≥2 supports the diagnostic certainty of true HCM with a sensitivity of 79%, specificity of 99%, negative predictive value (NPV) of 55%, and positive predictive value (PPV) of 99%. CONCLUSION: The QRS duration in patient with HCM is significantly shorter compared with patients with HHD-related LVH. QRS duration can be used as a diagnosis marker to distinguish between HCM and HHD. The D-HCM score is a novel, simple, and accurate diagnosis tool for HCM patients with mild to moderate phenotypes.

Primary electrical diseases diagnosis, genetic and management.

Primary electrical diseases or channelopathies are inherited genetic alterations of the cell ionic and electrical behavior leading to various cardiac arrhythmias carrying the risk of sudden death. A descriptive review of the successively described channelopathies is made in this article, with emphasis on the clinical manifestations, the genetic background and the currently accepted therapeutic options.

Hybrid surgical ablation for persistent or long standing persistent atrial fibrillation: A French single centre experience.

BACKGROUND: Hybrid ablation for the treatment of atrial fibrillation is a single combined procedure consisting in a minimally thoracoscopic surgical ablation followed by a catheter ablation. This promising technique is recommended in persistent atrial fibrillation according to the current guidelines but is not routinely performed in France, mainly due to the absence of reimbursement by the French National Health Insurance. AIMS: The aim of this prospective and single-centre study was to analyse, for the first time in France, the feasibility, efficacy and complication rates of hybrid ablation in patients with persistent atrial fibrillation. METHODS: Hybrid ablation was performed in 15 consecutive patients (13 men, mean age 61±6 years) with persistent (7 patients) or long standing persistent (8 patients) atrial fibrillation. RESULTS: Hybrid ablation was completed in 14/15 patients. Eleven patients returned in sinus rhythm during the procedure. Two patients (13%) had major per-procedural complications and 2 had minor complications. During an average follow-up of 25±6 months, 6 patients (40%) underwent a redo catheter ablation because of atrial tachycardia, mainly peri-mitral atrial flutter. At 1 year follow up, 14/15 patients were in sinus rhythm, including 11 free of antiarrhythmic drugs.

[Pulmonary vein stenosis after radiofrequency ablation for atrial fibrillation]. / Sténose des veines pulmonaires après radiofréquence pour fibrillation atriale.

INTRODUCTION: Pulmonary vein stenosis is a rare condition with a high mortality. With the advent of radiofrequency ablation for atrial fibrillation a new cause of pulmonary vein stenosis has emerged. OBSERVATIONS: We report two cases of severe pulmonary vein stenosis. In the first case the diagnosis was obtained rapidly and balloon angioplasty with stent implantation was performed in the two left pulmonary veins. Recurrent occlusion occurred within the stents, extensive pulmonary infiltrates resembling pulmonary venous infarction developed and the patient died. In the second case the diagnosis was missed initially because the clinical picture suggested thrombo-embolic disease or infection. Balloon angioplasty with stent implantation was performed later. Restenosis occurred after 18 months. These two cases illustrate the frequency with which percutaneously inserted venous prostheses thombose. CONCLUSIONS: Clinicians should be familiar with the possibility of the development of pulmonary vein stenosis after radiofrequency ablation for atrial fibrillation. Pulmonary vein stenosis remains a difficult condition to manage. The pulmonary infarction should probably be considered as an urgent indication for surgical resection or even transplantation.

Research of predictive factors for cardiac resynchronization therapy: a prospective study comparing data from phase-analysis of gated myocardial perfusion single-photon computed tomography and echocardiography : Trying to anticipate response to CRT.

BACKGROUND: Cardiac resynchronization therapy (CRT) reduces morbidity and mortality in chronic systolic heart failure. About 20% of implanted patients are considered as "non-responders". This study aimed to evaluate gated myocardial perfusion single-photon emission computed tomography (GMPS) phase parameters as compared to echocardiography in the assessment of predictors for response to CRT before and after CRT activation. METHODS: Forty-two patients were prospectively included during 15 months. A single injection of 99mTc-tetrofosmin was used to acquire GMPS phase pre- and post-CRT activation. Indicators of positive CRT response were improvement of functional status and 15% reduction in left ventricular end-systolic volume at 3 months. RESULTS: Phase parameters at baseline were similar in the two groups with no influence of perfusion data. Phase parameters after CRT activation were significantly improved in the responders' group (Δ Bandwidth -19° ± 24° vs. 13° ± 31°, p = 0.001; Δ SD -20° ± 30° vs. 26° ± 46°, p = 0.001; Δ Entropy -11 ± 12 vs. 2 ± 6%, p = 0.001). Feasibility and reproducibility were higher for GMPS. CONCLUSION: Acute phase modifications after CRT activation may predict response to CRT immediately after implantation, but not at baseline, even when adjusted to perfusion data.

Prevalence, characteristics, and prognosis role of type 1 ST elevation in the peripheral ECG leads in patients with Brugada syndrome.

BACKGROUND: Despite isolated reports of Brugada syndrome (BrS) in the inferior or lateral leads, the prevalence and prognostic value of ST elevation in the peripheral electrocardiographic (ECG) leads in patients with BrS remain poorly known. OBJECTIVE: To study the prevalence, characteristics, and prognostic value of type 1 ST elevation and ST depression in the peripheral ECG leads in a large cohort of patients with BrS. METHODS: ECGs from 323 patients with BrS (age 47 ± 13 years; 257 men) with spontaneous (n = 141) or drug-induced (n = 182) type 1 ECG were retrospectively reviewed. Two hundred twenty-five (70%) patients were asymptomatic, 72 (22%) patients presented with unexplained syncope, and 26 (8%) patients presented with sudden death (12 patients) or appropriated implantable cardioverter-defibrillator therapies (14 patients) at diagnosis or over a mean follow-up of 48 ± 34 months. RESULTS: Thirty (9%) patients presented with type 1 ST elevation in at least 1 peripheral lead (22 patients in the aVR leads, 2 in the inferior leads, 5 in both aVR and inferior leads, and 1 in the aVR and VL leads). Patients with type 1 ST elevation in the peripheral leads more often had mutations in the SCN5A gene, were more often inducible, had slower heart rate, and higher J-wave amplitude in the right precordial leads. Twenty-seven percent (8 of 30) of the patients with type 1 ST elevation in the peripheral leads experimented sudden death/appropriate implantable cardioverter-defibrillator therapy, whereas it occurred in only 6% (18 of 293) of other patients (P < .0001). In multivariate analysis, type 1 ECG in the peripheral leads was independently associated with malignant arrhythmic events (odds ratio 4.58; 95% confidence interval 1.7-12.32; P = .0025). CONCLUSIONS: Type 1 ST elevation in the peripheral ECG leads can be seen in 10% of the patients with BrS and is an independent predictor for a malignant arrhythmic event.