Temporal association between drops in thoracic impedance and malignant ventricular arrhythmia: A longitudinal analysis of remote monitoring trends.

INTRODUCTION: Thoracic impedance (TI) drops measured by implantable cardioverter-defibrillators (ICDs) have been reported to correlate with ventricular tachycardia/fibrillation (VT/VF). The aim of our study was to assess the temporal association of decreasing TI trends with VT/VF episodes through a longitudinal analysis of daily remote monitoring data from ICDs and cardiac resynchronization therapy defibrillators (CRT-Ds). METHODS AND RESULTS: Retrospective data from 2384 patients were randomized 1:1 into a derivation or validation cohort. The TI decrease rate was defined as the percentage of rolling weeks with a continuously decreasing TI trend. The derivation cohort was used to determine a TI decrease rate threshold for a ≥99% specificity of arrhythmia prediction. The associated risk of VT/VF episodes was estimated in the validation cohort by dividing the available follow-up into 60-day assessment intervals. Analyses were performed separately for 1354 ICD and 1030 CRT-D patients. During a median follow-up of 2.0 years, 727 patients (30.4%) experienced 3298 confirmed VT/VF episodes. In the ICD group, a TI decrease rate of >60% was associated with a higher risk of VT/VF episode in a 60-day assessment interval (stratified hazard ratio, 1.42; 95% confidence interval (CI), 1.05-1.92; p = .023). The TI decrease preceded (40.8%) or followed (59.2%) the VT/VF episodes. In the CRT-D group, no association between TI decrease and VT/VF episodes was observed (p = .84). CONCLUSION: In our longitudinal analysis, TI decrease was associated with VT/VF episodes only in ICD patients. Preventive interventions may be difficult since episodes can occur before or after TI decrease.

Multiparametric identification of subclinical atrial fibrillation after an embolic stroke of undetermined source.

BACKGROUND: Subclinical atrial fibrillation (SCAF) may represent a cause of embolic stroke of undetermined source (ESUS) and its detection has important implications for secondary prevention with anticoagulation. Indications to implantable cardiac monitors (ICM) include SCAF detection. The aims of this study were to (1) evaluate the frequency of ICM-detected SCAF; (2) determine predictors of SCAF; and (3) identify patients who would benefit most from ICM implantation. METHODS: Between February 2017 and November 2020, all consecutive patients referred for ICM implantation after a diagnosis of ESUS and without previous history of atrial fibrillation or atrial flutter were included in this study. SCAF was diagnosed if the ICM electrogram demonstrated an episode of irregularly irregular rhythm without distinct P waves lasting > 2 min. RESULTS: We enrolled 109 patients (age 66, SD = 13 years; 36% females). During a median follow-up of 19.2 (IQR 11.0-27.5) months, SCAF episodes were detected in 36 (33%) patients. Only abnormal P wave terminal force in lead V1, left atrial end-systolic indexed volume > 34 ml/m2, and BMI > 25 kg/m2 were independently associated with an increased risk of SCAF (HR 2.44, 95% CI 1.14-5.21, p = 0.021; HR 2.39, 95% CI 1.11-5.13, p = 0.026; and HR 2.64, 95% CI 1.06-6.49, p = 0.036 respectively). The ROC curve showed that the presence of all three parameters had the best accuracy (74%) to predict SCAF detection (sensitivity 39%, specificity 91%). CONCLUSION: A multiparametric evaluation has the best accuracy to predict SCAF in ESUS patients and may help identifying those who would benefit most from ICM.

X-ray management in electrophysiology: a survey of the Italian Association of Arrhythmology and Cardiac Pacing (AIAC).

AIMS: Radiation use in medicine has significantly increased over the last decade, and cardiologists are among the specialists most responsible for X-ray exposure. The present study investigates a broad range of aspects, from specific European Union directives to general practical principles, related to radiation management among a national cohort of cardiologists. METHODS AND RESULTS: A voluntary 31-question survey was run on the Italian Arrhythmology and Pacing Society (AIAC) website. From June 2019 to January 2020, 125 cardiologists, routinely performing interventional electrophysiology, participated in the survey. Eighty-seven (70.2%) participants are aware of the recent European Directive (Euratom 2013/59), although only 35 (28.2%) declare to have read the document in detail. Ninety-six (77.4%) participants register the dose delivered to the patient in each procedure, in 66.1% of the cases both as fluoroscopy time and dose area product. Years of exposition (P = 0.009) and working in centers performing pediatric procedures (P = 0.021) related to greater degree of X-ray equipment optimization. The majority of participants (72, 58.1%) did not recently attend radioprotection courses. The latter is related to increased awareness of techniques to reduce radiation exposure (96% vs. 81%, P = 0.022), registration of the delivered dose in each procedure (92% vs. 67%, P = 0.009), and X-ray equipment optimization (50% vs. 36%, P = 0.006). CONCLUSION: Italian interventional cardiologists show an acceptable level of radiation awareness and knowledge of updated European directives. However, there is clear space for improvement. Comparison to other health professionals, both at national and international levels, is needed to pursue proper X-ray management and protect public health.

Integration of activation maps of epicardial veins in computational cardiac electrophysiology.

In this work we address the issue of validating the monodomain equation used in combination with the Bueno-Orovio ionic model for the prediction of the activation times in cardiac electro-physiology of the left ventricle. To this aim, we consider four patients who suffered from Left Bundle Branch Block (LBBB). We use activation maps performed at the septum as input data for the model and maps at the epicardial veins for the validation. In particular, a first set (half) of the latter are used to estimate the conductivities of the patient and a second set (the remaining half) to compute the errors of the numerical simulations. We find an excellent agreement between measures and numerical results. Our validated computational tool could be used to accurately predict activation times at the epicardial veins with a short mapping, i.e. by using only a part (the most proximal) of the standard acquisition points, thus reducing the invasive procedure and exposure to radiation.

Use of impedance-based catheter tip-to-tissue contact assessment (electroanatomic coupling index, ECI) in typical right atrial flutter ablation.

PURPOSE: The electrical coupling index (ECI) (Abbott, USA) is a marker of tissue contact and ablation depth developed particularly for atrial fibrillation treatment. We sought to evaluate if these measures can be also a marker of lesion efficacy during cavotricuspid isthmus (CTI) ablation for typical right atrial flutter. METHODS: We assessed the ECI values in patients undergoing typical right atrial flutter point-by-point ablation guided by the Ensite Velocity Contact™ (St. Jude Medical, now Abbott St. Paul, MN, USA) electroanatomic mapping system. ECI values were collected before, during (at the plateau), and after radiofrequency (RF) delivery. The physician was blinded to ECI and judged ablation efficacy according to standard parameters (impedance drop, local potential reduction, and/or split in two separate potentials). Patients were followed up at 3 and 12 months. RESULTS: Fifteen consecutive patients (11 males, mean age 69.2 ± 10.6 years) with a history of typical right atrial flutter were included in this study. A total of 158 RF applications were assessed (mean 10.5 ± 6.6 per patient, range 6-28). The absolute and percentage ECI variations (pre-/post-ablation) were significantly greater when applications were effective (p < 0.001). A 12% drop in the ECI after ablation was identified by the ROC curve as the best cutoff value to discriminate between effective and ineffective ablation (sensitivity 94%, specificity 100%). Acute success was achieved in all patients with no complications and no recurrences during follow-up. CONCLUSION: The ECI appeared a reliable index to guide CTI ablation. A 12% drop of ECI during radiofrequency energy delivery was highly accurate in identifying effective lesion.

Coronary sinus activation patterns in patients with and without left bundle branch block undergoing electroanatomic mapping system-guided cardiac resynchronization therapy device implantation.

BACKGROUND: Implantation of the left ventricular (LV) lead in segments with delayed electrical activation may improve response to cardiac resynchronization therapy (CRT). OBJECTIVE: The purpose of this study was to evaluate the amount and regional distribution of LV electrical delay (LVED) in patients with or without left bundle branch block (LBBB). METHODS: We enrolled 60 patients who underwent electroanatomic mapping system-guided CRT device implantation. Activation mapping of the coronary sinus (CS) branches was performed using an insulated guidewire. LVED was defined as the interval between the beginning of the QRS complex on the surface electrocardiogram (ECG) and the local electrogram and expressed in milliseconds or as percentage of the total QRS duration (LVED%). RESULTS: Forty-three patients showed a LBBB and 17 a non-LBBB electrocardiographic pattern. A total of 148 CS branches (mean 2.5 per patient; range 2-4 per patient) were mapped. Patients with LBBB showed higher maximum LVED (135 ms [108-150 ms] vs 100 ms [103-110 ms]; P < .001) and LVED% (86% [79%-89%] vs 72% [54%-80%]; P < .001) than did patients without LBBB. The maximum LVED was recorded in mid-basal anterolateral or inferolateral LV segments (traditional CRT targets), significantly more often in patients with LBBB than in patients without LBBB (85% vs 59%; P = .02). The number of CS branches showing LVED >50% of the total QRS duration, >75% of the total QRS duration, and >85 ms was significantly higher in patients with LBBB than in patients without LBBB. CONCLUSION: Patients without LBBB showed lower LVED and more heterogeneous electrical activation of the CS than did patients with LBBB. This finding may contribute to a lower rate of response to CRT of patients without LBBB and suggests the use of activation mapping to guide LV lead placement.