AimThe neural cardiac therapy for heart failure (NECTAR-HF) was a randomized sham-controlled trial designed to evaluate whether a single dose of vagal nerve stimulation (VNS) would attenuate cardiac remodelling, improve cardiac function and increase exercise capacity in symptomatic heart failure patients with severe left ventricular (LV) systolic dysfunction despite guideline recommended medical therapy.MethodsPatients were randomized in a 2 : 1 ratio to receive therapy (VNS ON) or control (VNS OFF) for a 6-month period. The primary endpoint was the change in LV end systolic diameter (LVESD) at 6 months for control vs. therapy, with secondary endpoints of other echocardiography measurements, exercise capacity, quality-of-life assessments, 24-h Holter, and circulating biomarkers.ResultsOf the 96 implanted patients, 87 had paired datasets for the primary endpoint. Change in LVESD from baseline to 6 months was −0.04 ± 0.25 cm in the therapy group compared with −0.08 ± 0.32 cm in the control group (P = 0.60). Additional echocardiographic parameters of LV end diastolic dimension, LV end systolic volume, left ventricular end diastolic volume, LV ejection fraction, peak V02, and N-terminal pro-hormone brain natriuretic peptide failed to show superiority compared to the control group. However, there were statistically significant improvements in quality of life for the Minnesota Living with Heart Failure Questionnaire (P = 0.049), New York Heart Association class (P = 0.032), and the SF-36 Physical Component (P = 0.016) in the therapy group.ConclusionVagal nerve stimulation as delivered in the NECTAR-HF trial failed to demonstrate a significant effect on primary and secondary endpoint measures of cardiac remodelling and functional capacity in symptomatic heart failure patients, but quality-of-life measures showed significant improvement.

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AimsThe subcutaneous implantable cardioverter defibrillator (S-ICD) was introduced to overcome complications related to transvenous leads. Adoption of the S-ICD requires implanters to learn a new implantation technique. The aim of this study was to assess the learning curve for S-ICD implanters with respect to implant-related complications, procedure time, and inappropriate shocks (IASs).Methods and resultsIn a pooled cohort from two clinical S-ICD databases, the IDE Trial and the EFFORTLESS Registry, complications, IASs at 180 days follow-up and implant procedure duration were assessed. Patients were grouped in quartiles based on experience of the implanter and Kaplan–Meier estimates of complication and IAS rates were calculated. A total of 882 patients implanted in 61 centres by 107 implanters with a median of 4 implants (IQR 1,8) were analysed. There were a total of 59 patients with complications and 48 patients with IAS. The complication rate decreased significantly from 9.8% in Quartile 1 (least experience) to 5.4% in Quartile 4 (most experience) (P = 0.02) and non-significantly for IAS from 7.9 to 4.8% (P = 0.10). Multivariable analysis demonstrated a hazard ratio of 0.78 (P = 0.045) for complications and 1.01 (P = 0.958) for IAS. Dual-zone programming increased with experience of the individual implanter (P < 0.001), which reduced IAS significantly in the multivariable model (HR 0.44, P = 0.01). Procedure time decreased from 75 to 65 min (P < 0.001). The complication rate and procedure time stabilized after Quartile 2 (>13 implants).ConclusionThere is a short and significant learning curve associated with physicians adopting the S-ICD. Performance stabilizes after 13 implants.

Baseline interventricular delay is a potent independent predictor of remodeling and QOL responses with CRT.

Background Cardiac resynchronization therapy (CRT) reduces mortality and morbidity in selected heart failure (HF) patients. However, not all patients respond to CRT. Objective We hypothesized that a novel measure of electrical dyssynchrony, sum absolute QRST integral (SAI), predicts CRT response independent of QRS duration and morphology. Methods We retrospectively analyzed baseline 12-lead electrocardiograms (ECGs) of SMART-AV study participants [N=234, mean age 67 y, 70% male, 60% ischemic cardiomyopathy (ICM), mean left ventricular ejection fraction (LVEF) 25%, mean QRS duration 152ms, 77% had left bundle branch block (LBBB)]. Baseline pre-implant ECGs were digitized, transformed into orthogonal XYZ, and analyzed automatically by customized Matlab software. SAI was measured as an averaged arithmetic sum of absolute areas under the QRST curve. Patients were followed prospectively 6 months after CRT-D implantation. Patients with a decrease in left ventricular end-systolic volume ≥ 15mls after 6 months of CRT were considered responders. Logistic regression model was adjusted for age, gender, BBB morphology, LVEF, type of cardiomyopathy and QRS duration. Results Patients with the high mean SAI (3rd tertile) had 2.5 times greater odds of response than those with low mean SAI (1st tertile; OR 2.5, 95% CI 1.3–5.0, p=0.010), and 1.9 times greater than the lower two tertiles combined (OR 1.9, 95%CI 1.1–3.5; P=0.03). Adjustment for renal function (OR 2.33 (95%CI 1.32, 4.11); P=0.003) and LV lead position in RAO/LAO (OR 1.7 (95%CI 0.9, 3.2); P=0.087) did not attenuate association of SAI with outcome. Conclusion High SAI QRST independently predicts CRT response in the SMART-AV study.