br Conclusions CRT non responder rates have remained

Conclusions CRT non-responder rates have remained relatively stable despite attempts to improve patient selection and programming optimization. Many different methods for AV and VV delay optimization have been developed, and all have demonstrated that optimized delays, regardless of the method, result in acute improvements in LV diastolic and systolic function. These functional improvements have unfortunately not consistently translated into improvements in clinical outcomes or response rates to CRT. As routine AV delay optimization was performed in most trials demonstrating efficacy of CRT, it is a reasonable strategy that does not appear to be harmful. More recent data suggest, however, that an empiric AV delay of 120ms is not inferior to available optimization methods. Moreover, 3 large multicenter trials (FREEDOM, SMART AV, and ADAPTIVE CRT) failed to show superiority of IEGM-based optimization over nominal settings or echo techniques. This has led to the evaluation of other techniques for improving CRT outcome, such as placing LV leads in locations of late mechanical [76] or electrical activation [77]. Current techniques and available data make routine VV optimization impractical and unnecessary in the majority of patients. At the present time, the benefit of routine use of AV and VV interval optimization is unclear and may be most useful in the population of CRT “non-responders,” although the benefit of this strategy also requires further study.
Conflict of interest
Introduction The optimal management of perioperative anticoagulation in patients on warfarin therapy undergoing cardiac implantable electronic device (CIED) surgery is not yet established. Neither the recent American Heart Association/American College of Cardiology nor European Society of Cardiology guidelines mentioned device surgery in patients on chronic anticoagulation therapy. The 2008 guidelines from the American College of Chest Physicians (ACCP) have recommended the use of bridging anticoagulation with therapeutic dose of subcutaneous low-molecular-weight heparin (LMWH) or intravenous heparin in patients with mechanical itk inhibitor valves, atrial fibrillation, or venous thromboembolism who are at moderate or high risk for thromboembolic events [1]. This recommendation, however, was largely based on expert opinion. The new ACCP 2012 guidelines considered CIED surgery to be a procedure associated with an increased bleeding risk during perioperative antithrombotic administration [2]. CIED implantation in which separation of infraclavicular fascial layers and lack of suturing of unopposed tissues within device pocket may predispose to hematoma development. However, the updated guidelines did not provide specific recommendations on the management of this patient population. Recent surveys in Canada and United Kingdom revealed a lack of consensus among the CIED implanting physicians on whether to withhold anticoagulation and whether to use bridging therapy [3,4]. As increasing data are emerging during the last decade, we are here to provide an updated literature review and to offer our suggestions on the practical management of this important clinical issue.
Perioperative risk assessment of thromboembolism The current thromboembolic risk stratification is largely based on indirect evidence from studies outside of the perioperative setting involving patients with a mechanical heart valve, chronic atrial fibrillation or venous thromboembolism who either did not receive anticoagulation ( i.e., placebo-treated group in atrial fibrillation trials) or received less-effective treatment (e.g., aspirin-treated group in mechanical heart valve trials) [2]. Table 1 is a simplified risk stratification scheme for perioperative thromboembolism. Patients are classified as high risk (annual risk>10%), moderate risk (annual risk 5% to 10%), and low risk (annual risk<5%) for thromboembolism. An estimate of individual patient risk for perioperative thromboembolism is subjective but should consider both the baseline risk and the individual patient factors. For patients who are already on chronic warfarin therapy, most of them should have been considered by their physicians as moderate to high risk for thromboembolism.
Current management options
Risk of thromboembolism with short-term interruption of warfarin therapy A systematic review of perioperative anticoagulation suggested that risk of stroke for patients in whom warfarin was withheld might be substantially higher than would be predicted based on annual thromboembolic rates of patients with atrial fibrillation or a mechanical heart valve [5]. In a prospective, observational cohort study, 1293 episodes of warfarin therapy interruption in 1024 patients for an outpatient invasive procedure were included [6]. Warfarin therapy was withheld for ≤5 days in 83.8% of the episodes. Seven patients (0.7%) experienced postprocedural thromboembolic events. All those patients with arterial events were in atrial fibrillation with CHADS2 score of ≥2. In our study, 114 patients on chronic warfarin therapy had anticoagulation temporarily interrupted for CIED surgery without bridging therapy. Among them, 4 patients with atrial fibrillation and CHADS score ≥3 experienced a transient ischemic attack (TIA) even though these patients continued to receive aspirin [7]. Although it is generally safe for low risk patients, a short period of interruption of warfarin therapy during the periprocedural period in patients with moderate to high risk factors could potentially expose them to a small, but real thromboembolic threat.