Asirvatham, Samuel J

Background— Congenital long QT syndrome (LQTS) is characterized by QT prolongation. However, the QT interval itself is insufficient for diagnosis, unless the corrected QT interval is repeatedly ≥500 ms without an acquired explanation. Further, the majority of LQTS patients have a corrected QT interval below this threshold, and a significant minority has normal resting corrected QT interval values. Here, we aimed to develop and validate a novel, quantitative T wave morphological analysis program to differentiate LQTS patients from healthy controls. Methods and Results— We analyzed a genotyped cohort of 420 patients (22±16 years, 43% male) with either LQT1 (61%) or LQT2 (39%). ECG analysis was conducted using a novel, proprietary T wave analysis program that quantitates subtle changes in T wave morphology. The top 3 discriminating features in each ECG lead were determined and the lead with the best discrimination selected. Classification was performed using a linear discriminant classifier and validated on an untouched cohort. The top 3 features were Tpeak–Tend interval, T wave left slope, and T wave center of gravity x axis (last 25% of the T wave). Lead V6 had the best discrimination. It could distinguish 86.8% of LQTS patients from healthy controls. Moreover, it distinguished 83.33% of patients with concealed LQTS from controls, despite having essentially identical resting corrected QT interval values. Conclusions— T wave quantitative analysis on the 12-lead surface ECG provides an effective, novel tool to distinguish patients with either LQT1/LQT2 from healthy matched controls. It can provide guidance while mutation-specific genetic testing is in motion for family members.

Endovascular Stimulation for Treatment of HypotensionBackgroundWe have previously shown that sympathetic ganglia stimulation via the renal vein rapidly increases blood pressure. This study further investigated the optimal target sites and effective energy levels for stimulation of the renal vasculatures and nearby sympathetic ganglia for rapid increase in blood pressure.MethodsThe pre‐study protocol for endovascular stimulations included 2 minutes of stimulation (1–150 V and 10 pulses per second) and at least 2 minutes of rest during poststimulation. If blood pressure and/or heart rate were changed during the stimulation, time to return to baseline was allowed prior to the next stimulation.ResultsIn 11 acute canine studies, we performed 85 renal artery, 30 renal vein, and 8 hepatic vasculature stimulations. The mean arterial pressure (MAP) rapidly increased during stimulation of renal artery (95 ± 18 mmHg vs. 103 ± 15 mmHg; P < 0.0001), renal vein (90 ± 16 mmHg vs. 102 ± 20 mmHg; P = 0.001), and hepatic vasculatures (74 ± 8 mmHg vs. 82 ± 11 mmHg; P = 0.04). Predictors of a significant increase in MAP were energy >10 V focused on the left renal artery, bilateral renal arteries, and bilateral renal veins (especially the mid segment). Overall, heart rate was unchanged, but muscle fasciculation was observed in 22.0% with an output >10 V (range 15–150 V). Analysis after excluding the stimulations that resulted in fasciculation yielded similar results to the main findings.ConclusionsStimulation of intra‐abdominal vasculatures promptly increased the MAP and thus may be a potential treatment option for hypotension in autonomic disorders. Predictors of optimal stimulation include energy delivery and the site of stimulation (for the renal vasculatures), which informs the design of subsequent research.

Background— Although the vast majority of mitral valve prolapse (MVP) is benign, a small subset of patients, predominantly women, with bileaflet prolapse, complex ventricular ectopy (VE), and abnormal T waves comprise the recently described bileaflet MVP syndrome. We compared findings on electrophysiological study in bileaflet MVP syndrome patients with and without cardiac arrest to identify factors that may predispose to malignant ventricular arrhythmia. Methods and Results— Fourteen consecutive bileaflet MVP syndrome patients (n=13 women; median [limits], age at index ablation, 33.8 [21.0–58.7] years; ejection fraction, 60% [45%–67%]; all ≤ moderate mitral regurgitation; n=6 with previous cardiac arrest and implantable cardioverter defibrillator shocks for ventricular fibrillation; and n=8 without implantable cardioverter defibrillator although with symptomatic complex VE) were included. The 2 groups had similar baseline echocardiographic and electrocardiographic characteristics. All patients had at least 1 left ventricular papillary or fascicular VE focus. Purkinje origin VE was identified as the ventricular fibrillation trigger in 6 of 6 cardiac arrest patients (4 from papillary muscle) and Purkinje origin of dominant VE was seen in 5 of 8 (3 from papillary muscle) nonarrest patients. Acute success was seen in 17 of 19 procedures, and a ventricular fibrillation storm occurred within 24 hours of ablation in a single patient. Repeat ablation for recurrent symptomatic arrhythmia was performed in 6 patients. At 478 (39–2099) days of follow-up, 2 cardiac arrest patients received appropriate shocks. Symptoms from VE were reduced in 12 of 14. Conclusions— Bileaflet MVP syndrome is characterized by fascicular and papillary muscle VE that triggers ventricular fibrillation. Ablation of clinically dominant VE foci improves symptoms and reduces appropriate implantable cardioverter defibrillator shocks.

Background Incidental mobile thrombi are commonly found on endovascular leads of cardiac implantable electronic devices ( CIED s). Transseptal puncture for catheter ablation of arrhythmia poses a risk for paradoxical embolism. We examined risk of ischemic stroke, transient ischemic attack ( TIA ), or systemic embolism after transseptal ablation in patients with and without CIED s. Methods and Results Using a national administrative claims database, 31 720 patients who underwent a transseptal catheter ablation between January 2004 and September 2014 were identified. Two propensity‐matched cohorts were created by matching demographic variables, administrative variables, Charlson Comorbidity Index, CHA 2 DS 2 ‐Vasc score, and year and indication for ablation (5533 and 11 300 patients with and without CIED s). Incidence rates and Cox proportional hazards models were used to estimate risk of ischemic stroke, TIA , or systemic embolism for patients with and without CIED s. Impact of oral anticoagulation ( OAC ) use on the endpoint was examined. Over a mean follow‐up of 2.1 years, the incidence of the combined endpoint was 1.9 per 100 person‐years in patients with CIED s and 1.5 per 100 person‐years in patients without CIED s ( P =0.03). Among patients not on OAC , presence of a cardiac device was associated with an increased risk (hazard ratio [ HR ], 1.71 [1.24–2.35]; P <0.01), whereas there was no association noted among patients treated with OAC ( HR , 0.98 [0.75–1.28]). Conclusion CIED s are associated with an increased risk of stroke, TIA , or systemic embolism after transseptal ablation, but this risk is attenuated with postablation OAC use. Role of anticoagulation post‐transseptal ablation in patients with CIED warrants further investigation.