Antonio Frontera

Catheter ablation of atrial fibrillation in patients with diabetes mellitus: a systematic review and meta-analysis.

AIMSnDiabetes mellitus (DM) and atrial fibrillation (AF) share pathophysiological links, as supported by the high prevalence of AF within DM patients. Catheter ablation of AF (AFCA) is an established therapeutic option for rhythm control in drug resistant symptomatic patients. Its efficacy and safety among patients with DM is based on small populations, and long-term outcome is unknown. The present systematic review and meta-analysis aims to assess safety and long-term outcome of AFCA in DM patients, focusing on predictors of recurrence.nnnMETHODS AND RESULTSnA systematic review was conducted in MEDLINE/PubMed and Cochrane Library. Randomized controlled trials, clinical trials, and observational studies including patients with DM undergoing AFCA were screened and included if matching inclusion and exclusion criteria. Fifteen studies were included, adding up to 1464 patients. Mean follow-up was 27 (20-33) months. Overall complication rate was 3.5 (1.5-5.0)%. Efficacy in maintaining sinus rhythm at follow-up end was 66 (58-73)%. Meta-regression analysis revealed that advanced age (P < 0.001), higher body mass index (P < 0.001), and higher basal glycated haemoglobin level (P < 0.001) related to higher incidence of arrhythmic recurrences. Performing AFCA lead to a reduction of patients requiring treatment with antiarrhythmic drugs (AADs) from 55 (46-74)% at baseline to 29 (17-41)% (P < 0.001) at follow-up end.nnnCONCLUSIONSnCatheter ablation of AF safety and efficacy in DM patients is similar to general population, especially when performed in younger patients with satisfactory glycemic control. Catheter ablation of AF reduces the amount of patients requiring AADs, an additional benefit in this population commonly exposed to adverse effects of AF pharmacological treatments.

Catheter Ablation of Atrial Fibrillation in Patients With Left Ventricular Systolic Dysfunction A Systematic Review and Meta-Analysis

Background—Catheter ablation of atrial fibrillation (AFCA) is an established therapeutic option for rhythm control in symptomatic patients. Its efficacy and safety among patients with left ventricular systolic dysfunction is based on small populations, and data concerning long-term outcome are limited. We performed this meta-analysis to assess safety and long-term outcome of AFCA in patients with left ventricular systolic dysfunction, to evaluate predictors of recurrence and impact on left ventricular function. Methods and Results—A systematic review was conducted in MEDLINE/PubMed and Cochrane Library. Randomized controlled trials, clinical trials, and observational studies including patients with left ventricular systolic dysfunction undergoing AFCA were included. Twenty-six studies were selected, including 1838 patients. Mean follow-up was 23 (95% confidence interval, 18–40) months. Overall complication rate was 4.2% (3.6%–4.8%). Efficacy in maintaining sinus rhythm at follow-up end was 60% (54%–67%). Meta-regression analysis revealed that time since first atrial fibrillation (P=0.030) and heart failure (P=0.045) diagnosis related to higher, whereas absence of known structural heart disease (P=0.003) to lower incidence of atrial fibrillation recurrences. Left ventricular ejection fraction improved significantly during follow-up by 13% (P<0.001), with a significant reduction of patients presenting an ejection fraction <35% (P<0.001). N-terminal pro-brain natriuretic peptide blood levels decreased by 620 pg/mL (P<0.001). Conclusions—AFCA efficacy in patients with impaired left ventricular systolic function improves when performed early in the natural history of atrial fibrillation and heart failure. AFCA provides long-term benefits on left ventricular function, significantly reducing the number of patients with severely impaired systolic function.

Smart-watches: a potential challenger to the implantable loop recorder?

The newest generation of smart-watches offer heart rate monitoring technology via photoplethysmography, a technology shown to demonstrate impressive ability in diagnosing arrhythmias including atrial fibrillation. Combining such technology with the portability, connectivity and other location and activity tracking features smart-watches could represent a powerful new tool in extended non-invasive arrhythmia detection. The technology itself, including potential uses and limitations, is discussed. There is a need for further software development but crucially, further work into clarifying the diagnostic accuracy of such technology.

Characterization of the Left-Sided Substrate in Arrhythmogenic Right Ventricular Cardiomyopathy

Background—The correlates of left ventricular (LV) substrate in arrhythmogenic right ventricular (RV) cardiomyopathy are largely unknown. Methods and Results—Thirty-two patients with arrhythmogenic RV cardiomyopathy (47±14 years; 6 women) were included. RV and LV dysplasia were defined from multidetector computed tomography and cardiac magnetic resonance imaging. Arrhythmias were characterized as right-sided or left-sided on 12-lead ECG recordings at baseline and during isoproterenol testing. In 14 patients, the imaging substrate was compared with voltage mapping and local abnormal ventricular activity. Imaging abnormalities were found in 32 (100%) and 21 (66%) patients on the RV and LV, respectively, intramyocardial fat on multidetector computed tomography being the most sensitive feature. LV involvement related to none of the Task Force criteria. Right-sided arrhythmias were more frequent than left-sided arrhythmias (P=0.003) although the latter were more frequent in case of LV involvement (P=0.02). The agreement between low voltage and fat on multidetector computed tomography was high on the RV when using either endocardial unipolar or epicardial bipolar data (&kgr;=0.82 and &kgr;=0.78, respectively) but lower on the LV (&kgr;=0.54 for epicardial bipolar). LV local abnormal ventricular activity was found in all patients with LV involvement, and none of the others. The density of local abnormal ventricular activity within fat areas was similar between the RV and LV (P=0.57). Conclusions—LV substrate is frequent in arrhythmogenic RV cardiomyopathy, but poorly identified by current diagnostic strategies. Left-sided arrhythmias are more frequent in case of LV involvement. LV fat hosts the same density of local abnormal ventricular activity as RV fat, but is less efficiently detected by voltage mapping. These results support the need for alternative diagnostic strategies to identify LV dysplasia.

Impact of New Technologies and Approaches for Post–Myocardial Infarction Ventricular Tachycardia Ablation During Long-Term Follow-Up

Background—During the past years, many innovations have been introduced to facilitate catheter ablation of post–myocardial infarction ventricular tachycardia. However, the predictors of outcome after ablation were not thoroughly studied. Methods and Results—From 2009 to 2013, consecutive patients referred for post–myocardial infarction ventricular tachycardia ablation were included. The end point of the procedure was complete elimination of local abnormal ventricular activities (LAVA) and ventricular tachycardia (VT) noninducibility. The predictors of outcome with primary end point of VT recurrence were assessed. A total of 125 patients were included (age: 64±11 years; 7 women) for 142 procedures. The left ventricle was accessed via transseptal, retrograde aortic, and epicardial approaches in 87%, 33%, and 37% of patients, respectively. Three-dimensional electroanatomical mapping system was used in 70%, multipolar catheter in 51%, and real-time image integration in 38% (from magnetic resonance imaging in 39% and multidetector computed tomography in 93%) of patients. Before ablation, VT was inducible in 75%, and endocardial/epicardial LAVA were present in 88%/75%. After ablation, complete LAVA elimination was achieved in 60%, and VT noninducibility in 83%. During a median follow-up of 850 days (interquartile range, 439–1707), VT recurrence was observed in 36%. Multivariable analysis identified 3 independent outcome predictors: the ability to achieve complete LAVA elimination (R2=0.29; P<0.0001; risk ratio=0.52 [0.38–0.70]), the use of real-time image integration (R2=0.21; P=0.0006; risk ratio=0.49 [0.33–0.74]), and the use of multipolar catheters (R2=0.08; P=0.05; risk ratio=0.75 [0.56–1.00]). Conclusions—Achievement of complete LAVA elimination and use of scar integration from imaging and multipolar catheters to focus high-density mapping are independent predictors of VT-free survival after catheter ablation for post–myocardial infarction ventricular tachycardia.

Body Surface Mapping to Guide Atrial Fibrillation Ablation

Atrial fibrillation (AF) is the most common rhythm disorder, and is strongly associated with thromboembolic events and heart failure. Over the past decade, catheter ablation of AF has advanced considerably with progressive improvement in success rates. However, interventional treatment is still challenging, especially for persistent and long-standing persistent AF. Recently, AF analysis using a non-invasive body surface mapping technique has been shown to identify localised reentrant and focal sources, which play an important role in driving and perpetuating AF. Non-invasive mapping-guided ablation has also been reported to be effective for persistent AF. In this review, we describe new clinical insights obtained from non-invasive mapping of persistent AF to guide catheter ablation.

Vagal atrial fibrillation: What is it and should we treat it?

Vagal atrial fibrillation (AF) remains an under-recognised entity, affecting younger patients often with structurally normal hearts. Although there remains no universal definition or diagnostic criteria, in this review we describe recognised triggers and associated features, including a well-established association with athletic training. We explore potential mechanisms, including the role of the autonomic nervous system and ganglionated plexi in initiating and maintaining arrhythmia. We discuss the limited evidence base addressing the question of progression to persistent AF, and debate the merits of anti-arrhythmic treatment, as well as uncertainty regarding the risk of stroke. Differences in suggested pharmacological therapy are highlighted and as is the emerging promise of radiofrequency catheter ablation as a therapeutic option. As we recognise the emerging burden of vagal AF, we hope to explore the important similarities and differences crucial to developing our understanding of the disorder, and highlight some significant questions which remain unanswered.

Myocardial wall thinning predicts transmural substrate in patients with scar-related ventricular tachycardia

BACKGROUNDnScar-related ventricular tachycardia (VT) arises from specific substrate according to etiology.nnnOBJECTIVEnThe purpose of this study was to evaluate the relationship between wall thinning (WT) on multidetector computed tomography (MDCT) and local abnormal ventricular activity (LAVA) in patients with ischemic cardiomyopathy (ICM), postmyocarditis (PMC), and dilated cardiomyopathy (DCM).nnnMETHODSnForty-two patients (40 male, age 58 ± 13 years, 22 ICM, 11 PMC, 9 DCM) underwent MDCT before a combined endo-/epicardial VT ablation procedure. WT (<5 mm) and severe wall thinning (SWT) (<2 mm) area on MDCT were compared to the prevalence of endo-/epicardial LAVA during sinus rhythm.nnnRESULTSnWT and SWT were found on MDCT in 36 (86%) and 20 (48%) with 42 ± 37 cm2 and 26 ± 24 cm2, respectively. SWT was frequently detected in ICM (ICM 77% vs PMC 27% vs DCM 0%, P <.001). LAVA were frequently observed on the endocardium in ICM and on the epicardium in PMC. Endo-/epicardial facing LAVA were frequently found within SWT areas (91% in <2 mm, 9% in 2-5 mm, and 0% in >5 mm, P < .001). In SWT areas, the presence of endocardial LAVA in ICM and epicardial LAVA in PMC predicted opposite facing LAVA with sensitivity and specificity of 78% and 48% and 79% and 98%, respectively. SWT predicted epicardial LAVA in ICM and endocardial LAVA in PMC with sensitivity and specificity of 89% and 100%, and 100% and 100%, respectively.nnnCONCLUSIONnSWT is frequently found in ICM and PMC but is not common in DCM. SWT predicts LAVA on the opposite side of the wall (epicardial in ICM and endocardial in PMC), indicating transmural VT substrate. MDCT is useful for identifying VT substrate and helpful for understanding the mechanisms of the location of VT substrate domain.

Electrogram signature of specific activation patterns: Analysis of atrial tachycardias at high-density endocardial mapping

BACKGROUNDnThe significance of fractionated electrograms (EGMs) is object of debate, with multiple mechanisms described.nnnOBJECTIVEnUsing Rhythmia, a high-density mapping system, we sought to investigate the relationship between specific electrophysiological phenomena and EGM characteristics at those sites.nnnMETHODSnTwenty-five consecutive patients underwent high-density atrial mapping during atrial tachycardias. Bipolar EGMs were recorded with a 64-electrode basket catheter. The following atrial phenomena were identified: slow conduction (SC) areas, lines of block (LB), wavefront collisions (WFC), pivot sites (PS), and gaps. EGMs collected at these predefined areas were analyzed in terms of amplitude, duration, and morphology.nnnRESULTSnTwenty-five atrial maps with 195 sites of interest (1755 EGMs) were object of our analysis. Thirty-five percent were sites of SC: fractionation had low amplitude (0.16 ± 0.07 mV) and long duration (87.8 ± 10.7 ms); wavefront collisions were seen in 38% of sites with EGMs shorter in duration (46.5 ± 4.5 ms) and higher in voltage (0.58 ± 0.13 mV); 17% were lines of block, never responsible for fractionation (0.13 ± 0.05 mV; 122.4 ms ± 24.8 ms); 9% were PS with a high degree of fractionation (0.55 ± 0.15 mV; 85.8 ± 7.9 ms). Two gaps were identified (1%) with a low degree of fractionation.nnnCONCLUSIONnSpecific EGM characteristics in atrial tachycardia can be reproducibly linked to electrophysiological mechanisms. High-voltage and short-duration EGMs are associated with collision sites and PS that are unlikely to form critical sites for ablation; long-duration, low-voltage EGMs are associated with SC. However, not all SC regions will lie within the critical circuit and identification by only EGM characteristics cannot guide ablation.

Performance of a specific algorithm to minimize right ventricular pacing: A multicenter study

BACKGROUNDnIn Boston Scientific dual-chamber devices, the RYTHMIQ algorithm aims to minimize right ventricular pacing.nnnOBJECTIVEnWe evaluated the performance of this algorithm determining (1) the appropriateness of the switch from the AAI(R) mode with backup VVI pacing to the DDD(R) mode in case of suspected loss of atrioventricular (AV) conduction and (2) the rate of recorded pacemaker-mediated tachycardia (PMT) when AV hysteresis searches for restored AV conduction.nnnMETHODSnIn this multicenter study, we included 157 patients with a Boston Scientific dual-chamber device (40 pacemakers and 117 implantable cardioverter-defibrillators) without permanent AV conduction disorder and with the RYTHMIQ algorithm activated. We reviewed the last 10 remote monitoring-transmitted RYTHMIQ and PMT episodes.nnnRESULTSnWe analyzed 1266 episodes of switch in 142 patients (90%): 207 (16%) were appropriate and corresponded to loss of AV conduction, and 1059 (84%) were inappropriate, of which 701 (66%) were related to compensatory pause (premature atrial contraction, 7%; premature ventricular contraction, 597 (56%); or both, 27 (3%)) or to a premature ventricular contraction falling in the post-atrial pacing ventricular refractory period interval (219, 21%) and 94 (10%) were related to pacemaker dysfunction. One hundred fifty-four PMT episodes were diagnosed in 27 patients (17%). In 85 (69%) of correctly diagnosed episodes, the onset of PMT was directly related to the algorithm-related prolongation of the AV delay, promoting AV dissociation and retrograde conduction.nnnCONCLUSIONnThis study highlights some of the limitations of the RYTHMIQ algorithm: high rate of inappropriate switch and high rate of induction of PMT. This may have clinical implications in terms of selection of patients and may suggest required changes in the algorithm architecture.