Prospective Assessment of an Automated Intraprocedural 12-Lead ECG-Based System for Localization of Early Left Ventricular Activation.

BACKGROUND: To facilitate ablation of ventricular tachycardia (VT), an automated localization system to identify the site of origin of left ventricular activation in real time using the 12-lead ECG was developed. The objective of this study was to prospectively assess its accuracy. METHODS: The automated site of origin localization system consists of 3 steps: (1) localization of ventricular segment based on population templates, (2) population-based localization within a segment, and (3) patient-specific site localization. Localization error was assessed by the distance between the known reference site and the estimated site. RESULTS: In 19 patients undergoing 21 catheter ablation procedures of scar-related VT, site of origin localization accuracy was estimated using 552 left ventricular endocardial pacing sites pooled together and 25 VT-exit sites identified by contact mapping. For the 25 VT-exit sites, localization error of the population-based localization steps was within 10 mm. Patient-specific site localization achieved accuracy of within 3.5 mm after including up to 11 pacing (training) sites. Using 3 remotes (67.8±17.0 mm from the reference VT-exit site), and then 5 close pacing sites, resulted in localization error of 7.2±4.1 mm for the 25 identified VT-exit sites. In 2 emulated clinical procedure with 2 induced VTs, the site of origin localization system achieved accuracy within 4 mm. CONCLUSIONS: In this prospective validation study, the automated localization system achieved estimated accuracy within 10 mm and could thus provide clinical utility.

Cost Effectiveness of Ventricular Tachycardia Ablation Versus Escalation of Antiarrhythmic Drug Therapy: The VANISH Trial.

OBJECTIVES: This analysis uses the data from the randomized controlled trial to assess the cost effectiveness of catheter ablation (n = 132) versus escalated antiarrhythmic therapy (n = 127). BACKGROUND: For survivors of myocardial infarction with implantable cardioverter-defibrillator shocks despite antiarrhythmic drugs, the VANISH (Ventricular Tachycardia Ablation Versus Escalated Antiarrhythmic Drug Therapy in Ischemic Heart Disease) trial demonstrated improved clinical outcomes with catheter ablation compared with more aggressive antiarrhythmic pharmacotherapy. METHODS: Health care resource use and quality-of-life data were used to determine the cost effectiveness of catheter ablation. Published references were used to estimate costs (in 2015 Canadian dollars). The analysis was over 3 years, with a 5% discount rate. Adjustment was made for censoring and baseline utilities. RESULTS: Ablation resulted in greater quality-adjusted life-years (QALYs) than escalated drug therapy did (1.63 vs. 1.49; difference: 0.14; 95% confidence interval [CI]: -0.20 to 0.46) and higher cost ($65,126 vs. $60,269; difference: $4,857; 95% CI: -$19,757 to $27,106); with an incremental cost per QALY gained for ablation versus escalated drug therapy of $34,057 primarily due to the initial costs of ablation, which were partially offset by the costs of subsequent ablations and adverse outcomes in the escalated drug therapy arm. For patients with amiodarone-refractory ventricular tachycardia, ablation dominated escalated drug therapy, with greater QALYs (1.48 vs. 1.26; difference: 0.22; 95% CI: -0.19 to 0.59) and lower costs ($67,614 vs. $68,383; difference: -$769; 95% CI: -$35,330 to $27,092). For those with sotalol-refractory ventricular tachycardia, ablation resulted in similar QALYs (1.90 vs. 1.90; difference: -0.00; 95% CI: -0.59 to 0.62) and higher costs ($60,455 vs. $45,033; difference: $15,422; 95% CI: -$10,968 to $48,555). CONCLUSIONS: For the total trial population, results are suggestive that ablation is cost effective compared with escalation of drug therapy. This result was only manifest for the subgroup of patients whose qualifying arrhythmia occurred despite amiodarone.

Population-based evaluation of the management of antithrombotic therapy for atrial fibrillation.

BACKGROUND: Oral anticoagulation is an effective therapy for the prevention of cardioembolic complications in patients with atrial fibrillation. However, previous practice reviews have indicated that oral anticoagulants are often underused in this setting. Most of those reports have focused on reviews of hospitalized and institutionalized patients, or small geographical areas. OBJECTIVES: To determine the use of antithrombotic therapy for the treatment of atrial fibrillation in Nova Scotia and to survey the knowledge of antithrombotic therapy for atrial fibrillation among a concurrent cohort of primary care and specialist physicians involved in the management of patients with atrial fibrillation. PATIENTS AND METHODS: Patients with atrial fibrillation were identified through outpatient electrocardiography clinics held throughout Nova Scotia. Following consent of the primary care physicians, patients were contacted and completed a survey about their current management. Family physicians and specialists in Nova Scotia were also surveyed about the management of atrial fibrillation with antithrombotic therapy through the receipt of one of four case scenarios. RESULTS: Four hundred twenty-five patients participated in the cross-sectional survey. The mean patient age was 70.6 years, 255 (60%) were male and 398 (93.6%) had at least one risk factor for stroke in addition to atrial fibrillation. Two hundred ninety-four patients (69.2%) were receiving oral anticoagulants either alone (61.9%) or in combination with acetylsalicylic acid (ASA) (7.3%). An additional 85 patients (20%) received ASA alone. There was no difference in the rates of prescription of oral anticoagulants between elderly patients (75 years of age and older) and those younger than 75 years (71.7% versus 67.3%, 95% CI -13.1% to 4.5%; P=0.34). Overall, 72.0% of patients were receiving antithrombotic therapy in accordance with the 2001 guidelines of the American College of Chest Physicians, with no difference in the rates between individuals younger than 75 years (72.2%) and those over 75 years of age (71.7%) (absolute difference -0.5%, 95% CI -9.2% to 8.1%). Physician responses to case scenarios indicated that knowledge was high among both general practitioners and specialists regarding the appropriate use of oral anticoagulants for the prevention of thrombotic complications associated with atrial fibrillation. CONCLUSIONS: The appropriate use of oral antithrombotic therapy for the prevention of thrombotic complications of atrial fibrillation occurs in approximately 72% of patients studied in Nova Scotia, and physician knowledge about this indication is high. There was no bias against prescribing oral anticoagulants to elderly patients. The findings suggest that with time, education and evidence have positively impacted the use of antithrombotic therapy in these patients.

Quantitative assessment of myocardial ischemia by electrocardiographic and scintigraphic imaging.

We calculated distributions of epicardial potentials from body-surface electrocardiograms (ECGs) recorded during controlled myocardial ischemia and compared them with scintigraphic estimates of ischemia's extent/severity. The study population consisted of patients suffering from single-vessel coronary artery disease, referred for elective percutaneous transluminal coronary angioplasty of either the left anterior descending (n=7), the right coronary (n=9), or the left circumflex (n=2) artery. After the target vessel had been dilated, a 1960s "study" inflation was performed with a non-perfusion-type balloon catheter; at its commencement, technetium-99m sestamibi was injected via a femoral-vein catheter, and ECGs were recorded throughout the inflation from 120 leads. Single photon emission computed tomographic imaging was performed one hour after the injection of radionuclide to obtain an "occlusion image", and again one hour after a repeat injection 24 hours later to obtain a "control image"; the latter image was subtracted from the former, to derive a scintigraphic difference map (Delta map). The ECGs were signal-averaged over a 10-s window at preinflation and peak-inflation states, the preinflation averaged complexes were subtracted from the peak-inflation ones to produce body-surface Delta maps, and the corresponding Delta maps of epicardial potentials were calculated by applying the electrocardiographic inverse solution; this procedure is referred to as electrocardiographic imaging. The ECG-derived epicardial Delta maps related spatially to the scintigraphic Delta maps in all patients. The percent areas and surface integrals of positive values in ECG-derived Delta maps were found to be very good single-variable predictors of the extent (r=0.73; p=0.0006) and severity (r=0.72; p=0.0008) of the scintigraphically-estimated perfusion defect; a regression equation using two ECG-derived predictors further improved the agreement with scintigraphic estimates (r=0.81; p=0.0004 for estimates of severity). These findings suggest that noninvasive electrocardiographic imaging might provide quantitative estimates of the extent/severity of myocardial ischemia that agree closely with those provided by scintigraphic techniques.