Subclinical atrial tachyarrhythmias, without clinical atrial fibrillation, occurred frequently in patients with pacemakers and were associated with a significantly increased risk of ischemic stroke or systemic embolism. (Funded by St. Jude Medical; ASSERT ClinicalTrials.gov number, NCT00256152.).

We agree with Drs Govindarajan and Salgado that because dabigatran 110 mg BID is associated with a lower risk of bleeding, it might be preferred over the 150-mg BID dose in patients with atrial fibrillation who are Ͼ75 years old and in clinical situations associated with a high risk of bleeding (eg, soon after thrombolysis or in the first few days after an invasive procedure). 1,2 Although not approved in the United States, the 110-mg BID dose of dabigatran is approved for use in Canada (where at least one third of patients are receiving it), Europe, and several other countries for patients at high risk of bleeding.Dr Reiffel requests additional information about the risks of bleeding with dabigatran compared with warfarin in atrial fibrillation patients with multiple factors that might increase the level of dabigatran in the blood. These analyses from the RE-LY database are under way but involve only small numbers of patients and are expected to provide imprecise estimates of treatment effect. We agree that it would be prudent to consider the 110-mg BID dose of dabigatran in preference to the 150-mg BID dose in these patients.We agree with Dr Rosenstein et al that an antidote for dabigatran has the potential to stop bleeding if the anticoagulant effect of the drug can be reversed rapidly. Despite the lack of an antidote, the RE-LY trial demonstrated that both doses of dabigatran (110 mg BID and 150 mg BID) were associated with lower rates of total, intracranial, and life-threatening bleeding than warfarin. 2 The mechanism of reduction in intracranial bleeding with both doses of dabigatran compared with warfarin has not been established but might simply be explained by avoidance of the high risk of intracranial bleeding with warfarin. Reasons for the high risk of intracranial bleeding with warfarin require further investigation. Concomitant use of a proton pump inhibitor might mitigate the increase in risk of gastrointestinal bleeding associated with dabigatran 150 mg BID. Avoidance of concomitant antiplatelet therapy might also reduce the risk.

The Canadian Cardiovascular Society (CCS) atrial fibrillation (AF) guidelines program was developed to aid clinicians in the management of these complex patients, as well as to provide direction to policy makers and health care systems regarding related issues. The most recent comprehensive CCS AF guidelines update was published R ESUM ELe programme de lignes directrices de la Soci et e canadienne de cardiologie (SCC) en matière de fibrillation auriculaire (FA) a et e elabor e pour aider les cliniciens à prendre en charge ces patients complexes, ainsi que pour orienter les d ecideurs politiques et les systèmes de soins de sant e sur des questions connexes. La dernière edition

As compared with bridging therapy with heparin, a strategy of continued warfarin treatment at the time of pacemaker or ICD surgery markedly reduced the incidence of clinically significant device-pocket hematoma. (Funded by the Canadian Institutes of Health Research and the Ministry of Health and Long-Term Care of Ontario; BRUISE CONTROL ClinicalTrials.gov number, NCT00800137.).

Background-Among patients with implantable pacemakers and defibrillators, subclinical atrial fibrillation (SCAF) is associated with an increased risk of stroke; however, there is limited understanding of their temporal relationship. Methods and Results-The Asymptomatic Atrial Fibrillation and Stroke Evaluation in Pacemaker Patients and the AtrialFibrillation Reduction Atrial Pacing Trial (ASSERT) enrolled 2580 pacemaker and defibrillator patients aged ≥65 years with a history of hypertension but without a history of atrial fibrillation. Pacemakers and implantable cardioverter-defibrillators precisely logged the time and duration of all episodes of SCAF and recorded electrograms that were adjudicated by experts. We examined the temporal relationship between SCAF >6 minutes in duration and stroke or systemic embolism. Of 51 patients who experienced stroke or systemic embolism during follow-up, 26 (51%) had SCAF. In 18 patients (35%), SCAF was detected before stroke or systemic embolism. However, only 4 patients (8%) had SCAF detected within 30 days before stroke or systemic embolism, and only 1 of these 4 patients was experiencing SCAF at the time of the stroke. In the 14 patients with SCAF detected >30 days before stroke or systemic embolism, the most recent episode occurred at a median interval of 339 days (25th to 75th percentile, 211-619) earlier. Eight patients (16%) had SCAF detected only after their stroke, despite continuous monitoring for a median duration of 228 days (25th to 75th percentile, 202-719) before their event. Conclusions-Although SCAF is associated with an increased risk of stroke and embolism, very few patients had SCAF in the month before their event. Clinical Trial Registration-URL: http://www.clinicaltrials.gov. Unique identifier: NCT00256152.

In patients with ischemic cardiomyopathy and an ICD who had ventricular tachycardia despite antiarrhythmic drug therapy, there was a significantly lower rate of the composite primary outcome of death, ventricular tachycardia storm, or appropriate ICD shock among patients undergoing catheter ablation than among those receiving an escalation in antiarrhythmic drug therapy. (Funded by the Canadian Institutes of Health Research and others; VANISH ClinicalTrials.gov number, NCT00905853.).

No abstract

Background— Atrial fibrillation (AF) is the most common sustained arrhythmia; however, little is known about patients in a primary care setting from high-, middle-, and low-income countries. Methods and Results— This prospective registry enrolled patients presenting to an emergency department with AF at 164 sites in 46 countries representing all inhabited continents. Patient characteristics were compared among 9 major geographic regions. Between September 2008 and April 2011, 15 400 patients were enrolled. The average age was 65.9, standard deviation 14.8 years, ranging from 57.2, standard deviation 18.8 years in Africa, to 70.1, standard deviation 13.4 years in North America, P <0.001. Hypertension was globally the most common risk factor for AF, ranging in prevalence from 41.6% in India to 80.7% in Eastern Europe, P <0.001. Rheumatic heart disease was present in only 2.2% of North American patients, in comparison with 21.5% in Africa and 31.5% in India, P <0.001. The use of oral anticoagulation among patients with a CHADS 2 score of ≥2 was greatest in North America (65.7%) but was only 11.2% in China, P <0.001. The mean time in the therapeutic range was 62.4% in Western Europe, 50.9% in North America, but only between 32% and 40% in India, China, Southeast Asia, and Africa, P <0.001. Conclusions— There is a large global variation in age, risk factors, concomitant diseases, and treatment of AF among regions. Improving outcomes globally requires an understanding of this variation and the conduct of research focused on AF associated with different underlying conditions and treatment of AF and predisposing conditions in different socioeconomic settings.