A novel automated peak frequency annotation algorithm for identifying deceleration zones and ventricular tachycardia ablation sites.

BACKGROUND: Current annotation of local fractionated signals during ventricular electroanatomic mapping (EAM) requires manual input subject to variability and error. OBJECTIVES: The purpose of this study was to evaluate a novel peak frequency (PF) annotation software for its ability to automatically detect late potentials (LPs) and local abnormal ventricular activity (LAVA), determine an optimal range for display, and assess its impact on isochronal late activation mapping (ILAM). METHODS: EAM data from 25 patients who underwent ventricular tachycardia (VT) ablation were retrospectively analyzed. Samplings of electrogram PFs from areas of normal bipolar voltage, areas of low voltage, and areas of low voltage with fractioned signals were performed. An optimal range of frequency display was identified from these patients and applied to a validation cohort of 10 prospective patients to assess high PF within scar as a predictor of VT ablation target sites, in particular deceleration zones (DZs) identified by ILAM, LP, and LAVA. RESULTS: Voltage and PF ranges of normal endocardial tissue varied widely. Using 220 Hz as a frequency cutoff value in areas of low bipolar voltage, areas of high fractionation were identified with sensitivity of 91% and specificity of 85% There was no significant reduction in targeted DZ surface areas, and colocalization with DZs was observed in all cases. Applied to the prospective cohort, PF predicted fractionated areas and DZ in 9 of 10 patients. CONCLUSION: A PF annotation algorithm with a cutoff of 220 Hz accurately identifies areas of fractioned signals and accurately predicts DZs during ILAM.

Substrate Imaging Before Catheter Ablation of Ventricular Tachycardia: Risk Prediction for Acute Hemodynamic Decompensation.

BACKGROUND: The PAINESD (Pulmonary disease, Age, Ischemic cardiomyopathy, NYHA functional class, Ejection fraction, Storm, Diabetes mellitus) risk score has been validated as a predictor of periprocedural acute hemodynamic decompensation (AHD) in patients undergoing ventricular tachycardia (VT) ablation. Whether the addition of total scar volume (TSV) determined by preprocedure computed tomography imaging provides additional risk stratification has not been previously investigated. OBJECTIVES: The purpose of this study was to evaluate the impact of TSV on the risk of AHD and its adjunctive benefit to the PAINESD score newly modified as Pulmonary disease, Age, Ischemic cardiomyopathy, NYHA class, Ejection fraction, Storm, Scar volume, Diabetes mellitus (PAINES2D) based on the addition of scar volumes. METHODS: This was a retrospective analysis of all index VT ablations at a quaternary care center from 2017 to 2022. Associations between TSV and AHD were evaluated among patients with structural heart disease. RESULTS: Among 61 patients with TSV data, 13 (21%) had periprocedural AHD. TSV and PAINESD were independently associated with AHD risk. Both TSV and PAINESD were associated with AHD (P = 0.016 vs P = 0.053, respectively). The highest TSV tertile (≥37.30 mL) showed significant association with AHD (P = 0.018; OR: 4.80) compared to the other tertiles. The PAINESD and PAINES2D scores had significant impact on AHD (P = 0.046 and P = 0.010, respectively). The PAINES2D score had a greater impact on AHD compared to PAINESD (area under the curve: 0.73; P = 0.011; 95% CI: 0.56-0.91 and area under the curve: 0.67; P = 0.058; 95% CI: 0.49-0.85, respectively). CONCLUSIONS: Addition of TSV to a modified PAINESD score, PAINES2D, enhances risk prediction of AHD. Further prospective study is needed to assess benefit in various cardiomyopathy populations undergoing VT ablation.

Electromagnetic interference from left ventricular assist devices in patients with subcutaneous implantable cardioverter-defibrillators.

INTRODUCTION: Interactions of left ventricular assist devices (LVADs) with transvenous implantable cardioverter-defibrillator systems (ICDs) have been widely reported. However, less is known regarding the impact of electromagnetic interference (EMI) from LVADs on subcutaneous ICD function. METHODS AND RESULTS: A comprehensive literature search was performed on PubMed, Cochrane central registry, and Google Scholar using the search terms "subcutaneous implantable cardioverter-defibrillator and left ventricular assist devices," "electromagnetic interference, LVAD, and subcutaneous ICD," "EMI and S-ICD," and "inappropriate shocks, LVAD, and ICD." Demographic and programming data were extracted from the reports and authors as needed. A total of seven cases of EMI in LVAD patients with subcutaneous ICD (S-ICD) devices were found. In addition three previously unreported cases from our center were included. All cases involved either a heartware ventricular assist device or HeartMate III LVAD with a pre-existing S-ICD. In all patients, both the primary and secondary vectors had inappropriate sensing due to EMI. Three patients were reprogramed to the alternate vector with appropriate sensing. The S-ICD was either inactivated or replaced with a transvenous device in six patients. A single patient was left sensing in the alternate vector. There were no reports of inability to interrogate S-ICD systems in patients with LVADs. CONCLUSION: The risk of inappropriate shocks from LVADs should be considered in pre-existing patients with S-ICD, particularly when the heartware ventricular assist device or HeartMate III LVAD device is present. Reprogramming of the sensing vector can occasionally avoid this issue but often the S-ICD needs to be inactivated.

Higher initial weight-based heparin dosing is required with direct oral anticoagulants during catheter ablation for atrial fibrillation.

BACKGROUND: Heparin dosing of patients anticoagulated with direct oral anticoagulants (DOACs) undergoing atrial fibrillation (AF) ablation can be challenging as they require more heparin than those on warfarin therapy. We sought to compare periprocedural activated clotting times (ACTs) of patients on warfarin vs. DOAC and determine an optimal weight-based heparin dosage strategy. METHODS: Patients who underwent AF ablation over 28 months were reviewed for type of anticoagulation, intraprocedural heparin dosing, ACTs, and adverse outcomes. A heparin dosing strategy was then tested in a prospective validation cohort. RESULTS: There were 89 patients in the DOAC group and 43 in the warfarin group. Demographics, comorbidities, and complication rates were similar. Mean ACT and percentage of therapeutic ACTs were lower in the DOAC group, most significantly in those with a weight > 90 kg. In DOAC patients, a higher initial heparin bolus ≥ 150 units/kg yielded a higher percentage of therapeutic intraprocedural ACTs (49% ± 10 vs. 29% ± 7, p = 0.0008). In a prospective validation cohort of 25 patients administered an initial heparin bolus ≥ 150 units/kg, the mean ACT was 295 ± 33 and 49% of the ACTs collected were therapeutic, similar to findings of our high-dose retrospective subgroup. CONCLUSION: Patients on DOACs require more heparin during AF ablation to achieve therapeutic ACT. We suggest an initial heparin dose of at least 150 units/kg in this subset of patients, particularly in those with a weight > 90 kg.

Impact of Left Ventricular Hypertrophy on Peak Serum Troponin T Levels in Patients With Acute Myocardial Infarction.

Previous studies have reported that peak serum troponin I levels were disproportionately elevated in patients with acute anterior ST-segment elevation myocardial infarction (STEMI) and left ventricular (LV) hypertrophy (LVH) compared with those with normal LV mass. The purpose of this retrospective study was to assess the relation of peak serum troponin T levels in patients with normal LV mass and in subjects with mild, moderate, and severe LVH in patients with acute STEMI or non-ST segment elevation myocardial infarction (NSTEMI) when stratified on variables that might be expected to affect serum troponin T levels. The study population consisted of 262 patients; 91 with STEMI and 161 with NSTEMI. Serum troponin levels and 2-dimensional echocardiograms were obtained within the first 24 hours of hospitalization for STEMI or NSTEMI. There was no significant difference in serum troponin T levels in LV mass and/or LVH groups (p = 0.3210). There was no significant difference in serum troponin T levels in LV mass and/or LVH groups when these data were stratified on third variables including serum creatinine >1.2 mg/dl (p = 0.3681), LV ejection fraction <60% (p = 0.0978), STEMI (p = 0.2576), NSTEMI (p = 0.4994), and location of severe coronary stenosis (p = 0.1981). The results of this study suggest that there is no association between peak serum troponin T levels and LV mass and/or LVH groups when such groups are stratified on a third variable that may influence peak serum troponin T levels.

Third-degree burns associated with transcutaneous pacing.

A 69-year-old severely obese diabetic woman developed nausea, vomiting and diarrhoea which caused multiple metabolic alterations leading to hypotension and bradycardia due to slow atrioventricular junctional rhythm. Transcutaneous pacing (TCP) was initiated and maintained until the underlying heart rate and blood pressure normalised. TCP gel pads were kept in place prophylactically after pacing was terminated. Gel pads remained attached to the anterior thorax and back for a total of 36 hours. During this time the patient developed third-degree burns at the side of gel pad attachment. With appropriate wound care and after a long hospitalisation, the patient was discharged in stable condition. This case demonstrates that prolonged use of TCP gel pads without frequent replacement may lead to third-degree burns. It also suggest that prophylactic use of TCP gel pads should be avoided.

A QS pattern in leads V1 and V2 is associated with septal scarring independent of scar etiology - A cardiac magnetic resonance imaging study.

BACKGROUND: Isolated septal myocardial infarction (MI) is traditionally characterized by the presence of pathological Q waves in leads V1 and V2 on the surface electrocardiogram (ECG). The purpose of this study was to determine the relation between this ECG pattern and septal scar on cardiac magnetic resonance (CMR) imaging. METHODS: We retrospectively reviewed the medical records of 996 consecutive patients who received both ECG and CMR. RESULTS: Nineteen patients had a Q wave in leads V1 and V2. Septal scar was present in all 19 patients. Based on CMR imaging criteria, septal scars were ischemic in 8 patients (42%) and non-ischemic in 11 patients (58%). CONCLUSION: The results suggest that the presence of a QS pattern in leads V1 and V2 on the surface ECG is highly predictive of the presence of a septal myocardial scar, but is not diagnostic for septal MI, even after excluding comorbidities known to produce a pseudo-septal MI pattern.