Clinical Value of the Postpacing Interval for Mapping of Ventricular Tachycardia in Patients with Prior Myocardial Infarction

Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/72569/1/j.1540-8167.1999.tb00640.x.pd

Dronedarone in patients with congestive heart failure: insights from ATHENA

Dronedarone is a new multichannel blocking antiarrhythmic drug for treatment of atrial fibrillation (AF). In patients with recently decompensated congestive heart failure (CHF) and depressed LV function, the drug was associated with excess mortality compared with a placebo group. The present study aimed to analyse in detail the effects of dronedarone on mortality and morbidity in AF patients CHF. We performed a post hoc analysis of ATHENA, a large placebo-controlled outcome trial in 4628 patients with paroxysmal or persistent AF, to evaluate the relationship between clinical outcomes and dronedarone therapy in patients with stable CHF. The primary outcome was time to first cardiovascular (CV) hospitalization or death. There were 209 patients with NYHA class II/III CHF and a left ventricular ejection fraction <0.40 at baseline (114 placebo, 95 dronedarone patients). A primary outcome event occurred in 59/114 placebo patients compared with 42/95 dronedarone patients [hazard ratio (HR) 0.78, 95% CI = 0.52-1.16]. Twenty of 114 placebo patients and 12/95 dronedarone patients died during the study (HR 0.71, 95% CI = 0.34-1.44). Fifty-four placebo and 42 dronedarone patients were hospitalized for an intermittent episode of NYHA class IV CHF (HR = 0.78, 95% CI = 0.52-1.17). In this post-hoc analysis of ATHENA patients with AF and stable CHF, dronedarone did not increase mortality and showed a reduction of CV hospitalization or death similar to the overall population. However, in the light of the ANtiarrhythmic trial with DROnedarone in Moderate to severe CHF Evaluating morbidity DecreAse study, dronedarone should be contraindicated in patients with NYHA class IV or unstable NYHA classes II and III CHF

Microvolt T-Wave Alternans Physiological Basis, Methods of Measurement, and Clinical Utility—Consensus Guideline by International Society for Holter and Noninvasive Electrocardiology

This consensus guideline was prepared on behalf of the International Society for Holter and Noninvasive Electrocardiology and is cosponsored by the Japanese Circulation Society, the Computers in Cardiology Working Group on e-Cardiology of the European Society of Cardiology, and the European Cardiac Arrhythmia Society. It discusses the electrocardiographic phenomenon of T-wave alternans (TWA) (i.e., a beat-to-beat alternation in the morphology and amplitude of the ST- segment or T-wave). This statement focuses on its physiological basis and measurement technologies and its clinical utility in stratifying risk for life-threatening ventricular arrhythmias. Signal processing techniques including the frequency-domain Spectral Method and the time-domain Modified Moving Average method have demonstrated the utility of TWA in arrhythmia risk stratification in prospective studies in >12,000 patients. The majority of exercise-based studies using both methods have reported high relative risks for cardiovascular mortality and for sudden cardiac death in patients with preserved as well as depressed left ventricular ejection fraction. Studies with ambulatory electrocardiogram-based TWA analysis with Modified Moving Average method have yielded significant predictive capacity. However, negative studies with the Spectral Method have also appeared, including 2 interventional studies in patients with implantable defibrillators. Meta-analyses have been performed to gain insights into this issue. Frontiers of TWA research include use in arrhythmia risk stratification of individuals with preserved ejection fraction, improvements in predictivity with quantitative analysis, and utility in guiding medical as well as device-based therapy. Overall, although TWA appears to be a useful marker of risk for arrhythmic and cardiovascular death, there is as yet no definitive evidence that it can guide therapy

Prediction of fatal or near-fatal cardiac arrhythmia events in patients with depressed left ventricular function after an acute myocardial infarction†

To determine whether risk stratification tests can predict serious arrhythmic events after acute myocardial infarction (AMI) in patients with reduced left ventricular ejection fraction (LVEF <= 0.40). A total of 5869 consecutive patients were screened in 10 European centres, and 312 patients (age 65 +/- 11 years) with a mean LVEF of 31 +/- 6% were included in the study. Heart rate variability/turbulence, ambient arrhythmias, signal-averaged electrocardiogram (SAECG), T-wave alternans, and programmed electrical stimulation (PES) were performed 6 weeks after AMI. The primary endpoint was ECG-documented ventricular fibrillation or symptomatic sustained ventricular tachycardia (VT). To document these arrhythmic events, the patients received an implantable ECG loop-recorder. There were 25 primary endpoints (8.0%) during the follow-up of 2 years. The strongest predictors of primary endpoint were measures of heart rate variability, e.g. hazard ratio (HR) for reduced very-low frequency component ( <5.7 ln ms(2)) adjusted for clinical variables was 7.0 (95% CI: 2.4-20.3, P <0.001). Induction of sustained monomorphic VT during PES (adjusted HR = 4.8, 95% CI, 1.7-13.4, P = 0.003) also predicted the primary endpoint. Fatal or near-fatal arrhythmias can be predicted by many risk stratification methods, especially by heart rate variability, in patients with reduced LVEF after AM

Can we improve outcomes in AF patients by early therapy?

Atrial fibrillation affects at least 1% of the population and causes marked society-wide morbidity and mortality. Current management of atrial fibrillation including antithrombotic therapy and management of concomitant conditions in all patients, rate control therapy in most patients, and rhythm control therapy in patients with severe atrial fibrillation-related symptoms can alleviate atrial fibrillation-related symptoms but can neither effectively prevent recurrent atrial fibrillation nor suppress atrial fibrillation-related complications. Hence, there is a need for better therapy of atrial fibrillation

Estimated incidence of previously undetected atrial fibrillation on a 14-day continuous electrocardiographic monitor and associated risk of stroke

Aims There is uncertainty about whether and how to perform screening for atrial fibrillation (AF). To estimate the incidence of previously undetected AF that would be captured using a continuous 14-day ECG monitor and the associated risk of stroke. Methods and results We analysed data from a cohort of patients >65 years old with hypertension and a pacemaker, but without known AF. For each participant, we simulated 1000 ECG monitors by randomly selecting 14-day windows in the 6 months following enrolment and calculated the average AF burden (total time in AF). We used Cox proportional hazards models adjusted for CHA(2)DS(2)-VASc score to estimate the risk of subsequent ischaemic stroke or systemic embolism (SSE) associated with burdens of AF > and 6 min was 3.10% (95% CI 2.53-3.72). This was consistent across strata of age and CHA(2)DS(2)-VASc scores. Over a mean follow-up of 2.4 years, the rate of SSE among patients with 6 min of AF. Conclusions Approximately 3% of individuals aged >65 years with hypertension may have more than 6 min of AF detected by a 14-day ECG monitor. This is associated with a stroke risk of over 2% per year. Whether oral anticoagulation will reduce stroke in these patients is unknown

Mechanism of Ventricular Tachycardia Termination by Pacing at Left Ventricular Sites in Patients with Coronary Artery Disease

Objective: The mechanism by which pacing terminates ventricular tachycardia (VT) may depend on the location of the pacing site relative to the reentry circuit. The purpose of this study was to compare the mechanisms by which pacing terminates VT at left ventricular (LV) sites with and without concealed entrainment (CE) in patients with prior myocardial infarction.Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/46394/1/10840_2004_Article_391630.pd

Analysis During Sinus Rhythm of Critical Sites in Reentry Circuits of Postinfarction Ventricular Tachycardia

Background: Critical sites within reentry circuits of postinfarction ventricular tachycardia (VT) were identified during sinus rhythm (SR) and VT to determine whether electrogram characteristics during SR may be helpful in identifying successful ablation sites.Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/46421/1/10840_2004_Article_5100325.pd