Detection of new atrial fibrillation in patients with cardiac implanted electronic devices and factors associated with transition to higher device-detected atrial fibrillation burden.

BACKGROUND: In patients with cardiac implanted electronic devices, detection of new atrial fibrillation (AF) is associated with an increased risk of stroke. OBJECTIVE: To characterize daily AF burden at first detection and the rate of temporal transition to higher device-detected AF burden. METHODS: A pooled analysis of data from 3 prospective projects was analyzed, and 6580 patients (mean age 68 ± 12 years, 72% male) with no history of AF and no use of anticoagulants at baseline were identified. Various thresholds of daily AF burden (5 minutes and 1, 6, 12, and 23 hours) were analyzed. RESULTS: Among the study population of 6580 patients, a new AF, with an AF burden of ≥5 minutes, was detected in 2244 patients (34%) during a follow-up period of 2.4 ± 1.7 years. Among these patients, 1091 (49.8%) transitioned to a higher AF-burden threshold during follow-up. A higher duration of daily AF burden manifest at first detection and CHADS2 score ≥2 were associated with faster transition to a subsequent higher burden. Approximately 24% of patients transitioned from a lower threshold to a daily AF burden of ≥23 hours during follow-up. CONCLUSION: More than one-third of patients with no history of AF developed device-detected AF, with attainment of different thresholds of daily AF burden over time. Continuous long-term monitoring, especially when the initial detection corresponds to a higher daily AF burden and the CHADS2 score is ≥2, could support timely clinical decisions on anticoagulation by capturing transitions to higher AF-burden thresholds.

Reduction of inappropriate anti-tachycardia pacing therapies and shocks by a novel suite of detection algorithms in heart failure patients with cardiac resynchronization therapy defibrillators: a historical comparison of a prospective database.

AIMS: Implantable cardioverter defibrillators improve survival of patients at risk for ventricular arrhythmias, but inappropriate shocks occur in up to 30% of patients and have been associated with worse quality of life and prognosis. In heart failure patients with cardiac resynchronization therapy defibrillators (CRT-Ds), we evaluated whether a new generation of detection and discrimination algorithms reduces inappropriate shocks. METHODS AND RESULTS: We analysed 1983 Medtronic CRT-D patients (80% male, 67 ± 10 years), 1368 with standard devices (Control CRT-D) and 615 with new generation devices (New CRT-D). Expert electrophysiologists reviewed and classified the electrograms of all device-detected ventricular tachycardia/fibrillation episodes. Total follow-up was 3751 patients-years. Incidence of inappropriate shocks at 1 year was 2.8% [95% confidence interval (CI) = 2.0-3.5] in Control CRT-D and 0.9% (CI = 0.4-2.2) in New CRT-D (hazard ratio = 0.37, CI = 0.21-0.66, P < 0.001). In New CRT-D, inappropriate shocks were reduced by 77% [incidence rate ratio (IRR) = 0.23, CI = 0.16-0.35, P < 0.001] and inappropriate anti-tachycardia pacing by 81% (IRR = 0.19, CI = 0.11-0.335, P < 0.001). Annual rate per 100 patient-years for appropriate VF detections was 3.0 (CI = 2.1-4.2) in New CRT-D and 3.2 (CI = 2.1-5.0) in Control CRT-D (P = 0.68), for syncope was 0.4 (CI = 0.2-0.9) in New CRT-D and 0.7 (CI = 0.5-1.0) in Control CRT-D (P = 0.266), and for death was 1.0 (CI = 0.6-1.6) in New CRT-D and 3.5 (CI = 3.0-4.1) in Control CRT-D (P < 0.001). CONCLUSION: Detection and discrimination algorithms used in new generation CRT-D significantly reduced inappropriate shocks when compared with standard CRT-D. This result, with no compromise on VF sensitivity or risk of syncope, has important implications for patients' quality of life and prognosis.

Assessment of a standardized algorithm for cardiac pacing in older patients affected by severe unpredictable reflex syncopes.

AIMS: Opinions differ regarding the effectiveness of cardiac pacing in patients affected by reflex syncope. We assessed a standardized guideline-based algorithm in different forms of reflex syncope. METHODS AND RESULTS: In this prospective, multi-centre, observational study, patients aged >40 years, affected by severe unpredictable recurrent reflex syncopes, underwent carotid sinus massage (CSM), followed by tilt testing (TT) if CSM was negative, followed by implantation of an implantable loop recorder (ILR) if TT was negative. Those who had an asystolic response to one of these tests received a dual-chamber pacemaker. POPULATION: 253 patients, mean age 70 ± 12 years, median 4 (3-6) syncopes, 89% without or with short prodromes. Of these patients, 120 (47%) received a pacemaker and 106 were followed up for a mean of 13 ± 7 months: syncope recurred in 10 (9%). The recurrence rate was similar in 61 CSM+ (11%), 30 TT+ (7%), and 15 ILR+ (7%) patients. The actuarial total syncope recurrence rate was 9% (95% confidence interval (CI), 6-12) at 1 year and 15% (95% CI, 10-20) at 2 years and was significantly lower than that observed in the group of 124 patients with non-diagnostic tests who had received an ILR: i.e. 22% (95% CI, 18-26) at 1 year and 37% (95% CI, 30-43) at 2 years (P = 0.004). CONCLUSION: About half of older patients with severe recurrent syncopes without prodromes have an asystolic reflex for which cardiac pacing goes along with a low recurrence rate. The study supports the clinical utility of the algorithm for the selection of candidates to cardiac pacing in everyday clinical practice. CLINICAL TRIAL REGISTRATION: http://www.clinicaltrials.gov. Unique identifier: NCT01509534.

Effect of long-detection interval vs standard-detection interval for implantable cardioverter-defibrillators on antitachycardia pacing and shock delivery: the ADVANCE III randomized clinical trial.

IMPORTANCE: Using more intervals to detect ventricular tachyarrhythmias has been associated with reducing unnecessary implantable cardioverter-defibrillator (ICD) therapies. OBJECTIVE: To determine whether using 30 of 40 intervals to detect ventricular arrhythmias (VT) (long detection) during spontaneous fast VT episodes reduces antitachycardia pacing (ATP) and shock delivery more than 18 of 24 intervals (standard detection). DESIGN, SETTING, AND PARTICIPANTS: Randomized, single-blind, parallel-group trial that enrolled 1902 primary and secondary prevention patients (mean [SD] age, 65 [11] years; 84% men; 75% primary prevention ICD) with ischemic and nonischemic etiology undergoing first ICD implant at 1 of 94 international centers (March 2008-December 2010). INTERVENTIONS: Patients were randomized 1:1 to programming with long- (n = 948) or standard-detection (n = 954) intervals. MAIN OUTCOMES AND MEASURES: Total number of ATPs and shocks delivered for all episodes (primary outcomes) and inappropriate shocks, mortality, and syncopal rate (secondary outcomes). RESULTS: During a median follow-up of 12 months (interquartile range, 11-13), long-detection group had 346 delivered therapies (42 therapies per 100 person-years, 95% CI, 38-47) vs 557 in the standard-detection group (67 therapies per 100 person-years [95% CI, 62-73]; incident rate ratio [IRR], 0.63 [95% CI, 0.51-0.78]; P < .001). The long- vs the standard-detection group experienced 23 ATPs per 100 person-years (95% CI, 20-27) vs 37 ATPs per 100 person-years (95% CI, 33-41; IRR, 0.58 [95% CI, 0.47-0.72]; P < .001); 19 shocks per 100 person-years (95% CI, 16-22) vs 30 shocks per 100 person-years (95% CI, 26-34; IRR, 0.77 [95% CI, 0.59-1.01]; P = .06), with a significant difference in the probability of therapy occurrence (P < .001); and a reduction in first occurrence of inappropriate shock (5.1 per 100 patient-years [95% CI, 3.7-6.9] vs 11.6 [95% CI, 9.4-14.1]; IRR, 0.55 [95% CI, 0.36-0.85]; P = .008). Mortality (5.5 [95% CI, 4.0-7.2] vs 6.3 [95% CI, 4.8-8.2] per 100 patient-years; HR, 0.87; P = .50) and arrhythmic syncope rates (3.1 [95% CI, 2.6-4.6] vs 1.9 [95% CI, 1.1-3.1] per 100 patient-years; IRR, 1.60 [95% CI, 0.76-3.41]; P = .22) did not differ significantly between groups. CONCLUSIONS AND RELEVANCE: Among patients receiving an ICD, the use of a long- vs standard-detection interval resulted in a lower rate of ATP and shocks, and inappropriate shocks. This programming strategy may be an appropriate alternative. TRIAL REGISTRATION: clinicaltrials.gov Identifier: NCT00617175.

Surgical ablation of arrhythmias.

The surgical approach was the earliest therapeutic ablation of hyperkinetic arrhythmias. Following the progressive improvements in electrophysiological mapping and operative techniques, new surgical approaches have been developed for the treatment of those arrhythmias related to ectopic phenomena or reentry mechanisms. These procedures have been proven to be highly effective but the associated morbidity and mortality were unacceptably high. More recent and advanced techniques of transcatheter ablation have revolutionized the treatment of these arrhythmias and now represent the treatment of choice in the majority of cases. However, the significant reduction in the operative risk and the improvement in patient outcome with respect to the past, thanks to a better patient selection and to advances in the surgical and myocardial protection techniques, make do that the surgical approach to some forms of arrhythmias is still valid, especially in those cases requiring associated surgery: atrial tachyarrhythmias in patients with congenital heart disease, post-ischemic ventricular tachycardias in patients who necessitate myocardial revascularization, and/or ventricular remodeling and chronic or paroxysmal atrial fibrillation in patients who require cardiac surgery. New techniques such as radiofrequency, microwaves and cryoablation guarantee the creation of linear and transmural lesions with minimum damage to the cardiac structures and appear very interesting as they are surgically simple and associated with shorter procedure times and less complications. The possibility of performing the ablative procedure completely on the epicardial surface may open the way for atrial fibrillation surgery on a totally beating heart and for procedures that are ever less invasive thus enabling treatment of patients without associated surgical indications.