Search

BACKGROUND Diagnosing long QT syndrome (LQTS) remains challenging because of a considerable overlap in QT interval between patients with LQTS and healthy subjects. Characterizing T-wave morphology might improve LQTS diagnosis.OBJECTIVE The purpose of this study was to improve LQTS diagnosis by combining new polynomial-based T-wave morphology parameters with the corrected QT interval (QTc), age, and sex in a model.METHODS A retrospective cohort consisting of 333 patients with LQTS and 345 genotype-negative family members was used in this study. For each patient, a linear combination of the first 2 Hermite-Gauss (HG) polynomials was fitted to the STT segments of an average complex of all precordial leads and limb leads I and II. The weight coefficients as well as the error of the best fit were used to characterize T-wave morphology. Subjects were classified as patients with LQTS or controls by clinical QTc cutoffs and 3 support vector machine models fed with different features. An external cohort consisting of 72 patients and 45 controls was finally used to check the robustness of the models.RESULTS Baseline QTc cutoffs were specific but had low sensitivity in diagnosing LQTS. The model with T-wave morphology features, QTc, age, and sex had the best overall accuracy (84%), followed by a model with QTc, age, and sex (79%). The model with T-wave morphology features especially performed better in LQTS type 3 patients (69%).CONCLUSION T-wave morphologies can be characterized by fitting a linear combination of the first 2 Hermite-Gauss polynomials. Adding T-wave morphology characterization to age, sex, and QTc in a support vector machine model improves LQTS diagnosis.

BACKGROUND Idiopathic atrial fibrillation (AF) refers to a clinically lacking cardiovascular or pulmonary disease generating the pathophysiologic substrate for the arrhythmia. However, because idiopathic AF is associated with an increased event rate, it could be a harbinger of as-yet undetected underlying heart disease. OBJECTIVE The purpose of this study was to determine the prevalence of coronary artery disease (CAD) in patients diagnosed with idiopathic paroxysmal AF. METHODS Of the 3243 patients who underwent cardiac computed tomographic angiography (CTA) in our center between January 2008 and March 2011, we identified a total of 115 consecutive idiopathic paroxysmal AF patients who underwent CTA before electrophysiologic ablation. Patients were compared with 275 age-, sex-, and PROCAM risk score-matched healthy controls in permanent sinus rhythm. All patients were free of hypertension, diabetes, congestive heart failure, previous known coronary artery and peripheral vascular disease, previous stroke, thyroid, pulmonary, and renal disease, and structural abnormalities on echocardiography. RESULTS Controls more often showed a family history of CAD (38% vs 15%, P

Delayed left ventricular (LV) lateral wall (LVLW) activation is considered the electrical substrate underlying LV dysfunction amenable to cardiac resynchronization therapy (CRT).The purpose of this study was to assess LVLW activation in CRT candidates using coronary venous electroanatomic mapping (EAM) and to investigate whether the QRS area (QRSAREA) on the vectorcardiogram (VCG) can identify delayed LVLW activation.Fifty-one consecutive CRT candidates (29 left bundle branch block [LBBB], 15 intraventricular conduction delay [IVCD], 7 right bundle branch block [RBBB]) underwent intraprocedural coronary venous EAM using EnSite NavX. VCGs were constructed from preprocedural digital 12-lead ECGs using the Kors method. QRSAREA was assessed and compared to QRS duration and 5 different LBBB definitions.Delayed LVLW activation (activation time75% of QRS duration) occurred in 38 of 51 patients (29/29 LBBB, 8/15 IVCD, 1/7 RBBB). QRSAREA was larger in patients with than in patients without delayed LVLW activation (108 ± 42 µVs vs 51 ± 27 µVs, P.001), and identified delayed LVLW activation better than QRS duration (area under the curve 0.89 [95% confidence interval 0.79-0.99] vs 0.49 [95% confidence interval 0.33-0.65]). QRSAREA69 µVs diagnosed delayed LVLW activation with a higher sum of sensitivity (87%) and specificity (92%) than any of the LBBB definitions. Of the different LBBB definitions, the European Society of Cardiology textbook definition performed best with sensitivity of 76% and specificity of 100%.Coronary venous EAM can be used during CRT implantation to determine the presence of delayed LVLW activation. QRSAREA is a noninvasive alternative for intracardiac measurements of electrical activation, which identifies delayed LVLW activation better than QRS duration and LBBB morphology.

Figure 1 atrial fibrillation (AF) and hypertension underwent pulmonary vein (PV) isolation by radiofrequency (RF) catheter ablation 6 years ago. Because of recurrent symptomatic AF, dilated left atrium, and subsequent failure of antiarrhythmic drugs, he underwent a hybrid ablation procedure using video-assisted thoracoscopic epicardial bipolar RF ablation and endocardial check of the lesions. With the patient under general anesthesia, His and coronary sinus catheters were inserted via the left groin. After transseptal puncture, a circular mapping catheter was placed at the ostia of all PVs. Great difficulty was encountered when maneuvering across the left superior PV and was later attributed to stenosis. None of the PVs were electrically isolated. While trying to visualize the left-side PVs to place the epicardial bipolar RF clamp, remarkable segmental fibrosis causing narrowing of the left superior PV was discovered (Figure 1; videoscopic epicardial view of left superior PV; black arrow indicates fibrosed segment causing stenosis). This is the first time we were able to visualize epicardial PV fibrosis causing stenosis in humans. The patient’s cardiac highresolution computerized tomographic (CT) scan prior to the first procedure was normal. Subsequently, he underwent RF ablation of PV ostia for symptomatic AF. However, direct visualization of PV using videoscope-assisted epicardial ablation showed the fibrosis. PV stenosis is an important complication of AF catheter ablation, reported in up to 21% of patients with AF undergoing segmental PV isolation. During the ablation procedure, RF energy is delivered, causing thermal injury to tissue surrounding the PV. At the local site, the healthy tissue is replaced by scar, leading to electrical isolation of the PV. The location and volume of scar tissue formed may lead to PV narrowing. The majority of patients can be asymptomatic. However, depending on multiple factors such as number of PV affected, time course

Recently, several studies of cryoablation using balloon technology versus radiofrequency ablation of the pulmonary veins have shown that cryoablation of paroxysmal atrial fibrillation (PAF) promises to be an effective therapy with success rates similar to that of radiofrequency ablation. Cryothermal energy is known to be safer than other energy sources. The most frequently occurring complication of cryoablation by using a balloon is phrenic nerve palsy, which often occurs by positioning the balloon deep in a pulmonary vein (PV). We report a case of a 65-year old man with PAF in whom we performed a successful PV isolation using a 23-mm cryoballoon (Arctic Front, Medtronic Inc, Quebec Canada). The application of cryothermal energy in the left inferior PV [LIPV] was relatively deep in the PV (Figure 1A, arrows pointing to balloon [BL]). Temperatures reached 64°C. Four days after the procedure, the patient presented at the hospital with hemoptysis. A thoracic computed tomography (CT) scan showed no abnormalities. Bronchoscopy showed an erosion with blood effusion (diameter 3 to 4 mm) on the ventral side at the division of