T. Jared Bunch

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

AIMS Diabetes 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. 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 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. CONCLUSIONS Catheter 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.

Smooth muscle cells in human coronary atherosclerosis can originate from cells administered at marrow transplantation

Atherosclerosis is the major cause of adult mortality in the developed world, and a significant contributor to atherosclerotic plaque progression involves smooth muscle cell recruitment to the intima of the vessel wall. Controversy currently exists on the exact origin of these recruited cells. Here we use sex-mismatched bone marrow transplant subjects to show that smooth muscle cells throughout the atherosclerotic vessel wall can derive from donor bone marrow. We demonstrate extensive recruitment of these cells in diseased compared with undiseased segments and exclude cell–cell fusion events as a cause for this enrichment. These data have broad implications for our understanding of the cellular components of human atherosclerotic plaque and provide a potentially novel target for future diagnostic and therapeutic strategies.

Randomized Secondary Prevention Trial of Azithromycin in Patients With Coronary Artery Disease Primary Clinical Results of the ACADEMIC Study

BackgroundChlamydia pneumoniae is associated with coronary artery disease (CAD), although its causal role is uncertain. A small preliminary study reported a >50% reduction in ischemic events by azithromycin, an antibiotic effective against C pneumoniae, in seropositive CAD patients. We tested this prospectively in a larger, randomized, double-blind study. Methods and ResultsCAD patients (n=302) seropositive to C pneumoniae (IgG titers ≥1:16) were randomized to placebo or azithromycin 500 mg/d for 3 days and then 500 mg/wk for 3 months. The primary clinical end point included cardiovascular death, resuscitated cardiac arrest, nonfatal myocardial infarction (MI), stroke, unstable angina, and unplanned coronary revascularization at 2 years. Treatment groups were balanced, and azithromycin was generally well tolerated. During the trial, 47 first primary events occurred (cardiovascular death, 9; resuscitated cardiac arrest, 1; MI, 11; stroke, 3; unstable angina, 4; and unplanned coronary revascularization, 19), with 22 events in the azithromycin group and 25 in the placebo group. There was no significant difference in the 1 primary end point between the 2 groups (hazard ratio for azithromycin, 0.89; 95% CI, 0.51 to 1.61;P =0.74). Events included 9 versus 7 occurring within 6 months and 13 versus 18 between 6 and 24 months in the azithromycin and placebo groups, respectively. ConclusionsThis study suggests that antibiotic therapy with azithromycin is not associated with marked early reductions (≥50%) in ischemic events as suggested by an initial published report. However, a clinically worthwhile benefit (ie, 20% to 30%) is still possible, although it may be delayed. Larger (several thousand patient), longer-term (≥3 to 5 years) antibiotic studies are therefore indicated.

Patients treated with catheter ablation for atrial fibrillation have long-term rates of death, stroke, and dementia similar to patients without atrial fibrillation.

Outcomes in Patients With AF. Introduction: Atrial fibrillation (AF) adversely impacts mortality, stroke, heart failure, and dementia. AF ablation eliminates AF in most patients. We evaluated the long‐term impact of AF ablation on mortality, heart failure (HF), stroke, and dementia in a large system‐wide patient population.

Atrial fibrillation is independently associated with senile, vascular, and Alzheimer's dementia

BACKGROUND The aging population has resulted in more patients living with cardiovascular disease, such as atrial fibrillation (AF). Recent focus has been placed on understanding the long-term consequences of chronic cardiovascular disease, such as a potential increased risk of dementia. OBJECTIVE This study sought to determine whether there is an association between AF and dementia and whether their coexistence is an independent marker of risk. METHODS A total of 37,025 consecutive patients from the large ongoing prospective Intermountain Heart Collaborative Study database were evaluated and followed up for a mean of 5 years for the development of AF and dementia. Dementia was sub-typed into vascular (VD), senile (SD), Alzheimers (AD), and nonspecified (ND). RESULTS Of the 37,025 patients with a mean age of 60.6 +/- 17.9 years, 10,161 (27%) developed AF and 1,535 (4.1%) developed dementia (179 VD, 321 SD, 347 AD, 688 ND) during the 5-year follow-up. Patients with dementia were older and had higher rates of hypertension, coronary artery disease, renal failure, heart failure, and prior strokes. In age-based analysis, AF independently was significantly associated with all dementia types. The highest risk was in the younger group (<70). After dementia diagnosis, the presence of AF was associated with a marked increased risk of mortality (VD: hazard ratio [HR] = 1.38, P = .01; SD: HR = 1.41, P = .001; AD: HR = 1.45; ND: HR = 1.38, P <.0001). CONCLUSION AF was independently associated with all forms of dementia. Although dementia is strongly associated with aging, the highest risk of AD was in the younger group, in support of the observed association. The presence of AF also identified dementia patients at high risk of death.

Mechanisms of phrenic nerve injury during radiofrequency ablation at the pulmonary vein orifice.

Background: The phrenic nerve can be injured with radiofrequency energy delivery. Nevertheless, the mechanisms of injury are unknown. This study was undertaken to examine phrenic nerve tissue temperatures during ablation at the pulmonary vein (PV) orifice, assess the temperature dependence of injury, and to delineate the possible mechanisms of untoward nerve effects.

Percutaneous Implantation of an Entirely Intracardiac Leadless Pacemaker

BACKGROUND Cardiac pacemakers are limited by device-related complications, notably infection and problems related to pacemaker leads. We studied a miniaturized, fully self-contained leadless pacemaker that is nonsurgically implanted in the right ventricle with the use of a catheter. METHODS In this multicenter study, we implanted an active-fixation leadless cardiac pacemaker in patients who required permanent single-chamber ventricular pacing. The primary efficacy end point was both an acceptable pacing threshold (≤2.0 V at 0.4 msec) and an acceptable sensing amplitude (R wave ≥5.0 mV, or a value equal to or greater than the value at implantation) through 6 months. The primary safety end point was freedom from device-related serious adverse events through 6 months. In this ongoing study, the prespecified analysis of the primary end points was performed on data from the first 300 patients who completed 6 months of follow-up (primary cohort). The rates of the efficacy end point and safety end point were compared with performance goals (based on historical data) of 85% and 86%, respectively. Additional outcomes were assessed in all 526 patients who were enrolled as of June 2015 (the total cohort). RESULTS The leadless pacemaker was successfully implanted in 504 of the 526 patients in the total cohort (95.8%). The intention-to-treat primary efficacy end point was met in 270 of the 300 patients in the primary cohort (90.0%; 95% confidence interval [CI], 86.0 to 93.2, P=0.007), and the primary safety end point was met in 280 of the 300 patients (93.3%; 95% CI, 89.9 to 95.9; P<0.001). At 6 months, device-related serious adverse events were observed in 6.7% of the patients; events included device dislodgement with percutaneous retrieval (in 1.7%), cardiac perforation (in 1.3%), and pacing-threshold elevation requiring percutaneous retrieval and device replacement (in 1.3%). CONCLUSIONS The leadless cardiac pacemaker met prespecified pacing and sensing requirements in the large majority of patients. Device-related serious adverse events occurred in approximately 1 in 15 patients. (Funded by St. Jude Medical; LEADLESS II ClinicalTrials.gov number, NCT02030418.).

A Systematical Analysis of In Vivo Contact Forces on Virtual Catheter Tip/Tissue Surface Contact during Cardiac Mapping and Intervention

Introduction: While catheter tip/tissue contact has been shown to be an important determinant of ablative lesions in in vitro studies, the impact of contact on the outcomes of mapping and ablation in the intact heart has not been evaluated.

Outcomes After Cardiac Perforation During Radiofrequency Ablation of the Atrium

Background: Perforation during catheter procedures in either the atrium or ventricle is relatively uncommon, but potentially fatal if tamponade ensues. This study analyzes the occurrence and outcomes of cardiac perforation during catheter‐based radiofrequency ablation procedures in the left atrium.

FREEDOM FROM RECURRENT VENTRICULAR TACHYCARDIA AFTER CATHETER ABLATION IS ASSOCIATED WITH IMPROVED SURVIVAL IN PATIENTS WITH STRUCTURAL HEART DISEASE: AN INTERNATIONAL VT ABLATION CENTER COLLABORATIVE GROUP STUDY

BACKGROUND The impact of catheter ablation of ventricular tachycardia (VT) on all-cause mortality remains unknown. OBJECTIVE The purpose of this study was to examine the association between VT recurrence after ablation and survival in patients with scar-related VT. METHODS Analysis of 2061 patients with structural heart disease referred for catheter ablation of scar-related VT from 12 international centers was performed. Data on clinical and procedural variables, VT recurrence, and mortality were analyzed. Kaplan-Meier analysis was used to estimate freedom from recurrent VT, transplant, and death. Cox proportional hazards frailty models were used to analyze the effect of risk factors on VT recurrence and mortality. RESULTS One-year freedom from VT recurrence was 70% (72% in ischemic and 68% in nonischemic cardiomyopathy). Fifty-seven patients (3%) underwent cardiac transplantation, and 216 (10%) died during follow-up. At 1 year, the estimated rate of transplant and/or mortality was 15% (same for ischemic and nonischemic cardiomyopathy). Transplant-free survival was significantly higher in patients without VT recurrence than in those with recurrence (90% vs 71%, P<.001). In multivariable analysis, recurrence of VT after ablation showed the highest risk for transplant and/or mortality [hazard ratio 6.9 (95% CI 5.3-9.0), P<.001]. In patients with ejection fraction <30% and across all New York Heart Association functional classes, improved transplant-free survival was seen in those without VT recurrence. CONCLUSION Catheter ablation of VT in patients with structural heart disease results in 70% freedom from VT recurrence, with an overall transplant and/or mortality rate of 15% at 1 year. Freedom from VT recurrence is associated with improved transplant-free survival, independent of heart failure severity.