Aveir VR real-world performance and chronic pacing threshold prediction using mapping and fixation electrical data.

AIMS: Aveir VR performance and predictors for its pacing threshold (PCT) in a real-world cohort were investigated. METHODS: Electrical measurements at various stages of an Aveir VR implant were prospectively collected. Predictors for 3-month PCT were studied. A retrospective cohort of consecutive 139 Micra implants was used to compare the PCT evolution. High PCT was defined as ≥1.5 V, using a pulse width of 0.4 ms for Aveir and 0.24 ms for Micra. Excellent PCT was defined as ≤0.5 V at the respective pulse width. RESULTS: Among the 123 consecutive Aveir VR implant attempts, 122 (99.2%) were successful. The majority were of advanced age (mean 79.7) and small body size (mean BSA 1.60). Two patients (1.6%) experienced complications, including one pericardial effusion after device reposition and one intraoperative device dislodgement. Eighty-eight patients reached a 3-month follow-up. Aveir 3-month PCT was correlated with impedance at mapping (P = 0.015), tether mode (P < 0.001), end-of-procedure (P < 0.001), and mapping PCT (P = 0.035), but not with PCTs after fixation (P > 0.05). Tether mode impedance >470 ohms had 88% sensitivity and 71% specificity in predicting excellent 3-month PCT. Although it is more common for Aveir to have high PCT at end of procedure (11.5% for Aveir and 2.2% for Micra, P = 0.004), the rate at 3 months was similar (2.3% for Aveir and 3.1% for Micra, P = 1.000). CONCLUSION: Aveir VR demonstrated satisfactory performance in this high-risk cohort. Pacing thresholds tend to improve to a greater extent than Micra after implantation. The PCT after fixation, even after a waiting period, has limited predictive value for the chronic threshold. Low-mapping PCT and high intraoperative impedance predict chronic low PCT.

Personalized cardiac resynchronization therapy guided by real-time electrocardiographic imaging for patients with non-left bundle branch block.

BACKGROUND: Patients with heart failure and a non-left bundle branch block (non-LBBB) QRS pattern have a limited response to biventricular pacing (BVP). OBJECTIVE: A personalized cardiac resynchronization therapy (CRT) implantation approach guided by real-time electrocardiographic imaging (ECGi) was studied. METHODS: Twenty patients with left ventricular ejection fraction (LVEF) ≤ 35%, QRS duration ≥ 120 ms, and non-LBBB [13 (65%) with right bundle branch block and 7 (35%) with intraventricular conduction delay] were recruited. During CRT implantation, right atrial, right ventricular, coronary sinus, His-bundle, and/or left bundle leads were inserted. The total activation time (TAT) with different pacing combinations were measured in real time during implantation by ECGi. The configuration producing the shortest TAT was chosen. Clinical response was defined as ≥1 New York Heart Association class improvement. Echocardiographic response was defined as left ventricular end-systolic volume reduction ≥ 15% and/or LVEF improvement ≥ 10% at 6 months. RESULTS: After ECGi-guided CRT implantation, LVEF improved from 26% ± 6% to 34% ± 11% (P < .01) and New York Heart Association class improved from 3.0 ± 0.5 to 2.0 ± 0.6 (P < .01). Both clinical and echocardiographic response rates were 70%. The ECGi approach resulted in better acute electrical resynchronization over BVP as measured by TAT reduction (40% vs 14%; P < .01). The percentage of TAT reduction was found to be a strong predictor for echocardiographic response (area under the curve for the receiver operating characteristic curve 0.91; 95% confidence interval 0.78-1.00). A strong positive correlation between percentage TAT reduction and percentage LVEF improvement (Pearson R = 0.70; P = .001) was found. CONCLUSION: ECGi-guided CRT implantation in patients with non-LBBB generates superior acute electrical resynchronization compared with BVP and is associated with favorable clinical and echocardiographic outcomes.

Automatic algorithmic driven monitoring of atrioventricular nodal re-entrant tachycardia ablation to improve procedural safety.

Background: During slow pathway modification for atrioventricular nodal reentrant tachycardia, heart block may occur if ablation cannot be stopped in time in response to high risk electrogram features (HREF). Objectives: To develop an automatic algorithm to monitor HREF and terminate ablation earlier than human reaction. Methods: Digital electrogram data from 332 ablation runs from February 2020 to June 2022 were included. They were divided into training and validation sets which contained 126 and 206 ablation runs respectively. HREF in training set was measured. Then a program was developed with cutoff values decided from training set to capture all these HREF. Simulation ablation videos were rendered using validation set electrogram data. The videos were played to three independent electrophysiologists who each determined when to stop ablation. Timing of ablation termination, sensitivity, and specificity were compared between human and program. Results: Reasons for ablation termination in the training set include short AA time, short VV time, AV block and VA block. Cutoffs for the program were set to maximize program sensitivity. Sensitivity and specificity for the program in the validation set were 95.2% and 91.1% respectively, which were comparable to that of human performance at 93.5% and 95.4%. If HREF were recognized by both human and program, ablations were terminated earlier by the program 90.2% of times, by a median of 574 ms (interquartile range 412-807 ms, p < 0.001). Conclusion: Algorithmic-driven monitoring of slow pathway modification can supplement human judgement to improve ablation safety.

Catheter ablation of the left and right atrial appendages without isolation in persistent atrial fibrillation.

BACKGROUND: Electrical isolation of the left atrial appendage (LAA) improves outcomes of patients with persistent atrial fibrillation (AF) but may increase the risk of thromboembolism. OBJECTIVE: The purpose of this study was to describe a method to map and ablate appendage drivers without complete electrical isolation. METHODS: One hundred thirteen patients underwent an ablation procedure for persistent AF. The procedure was performed during AF and consisted of pulmonary vein and posterior LA isolation as well as ablation of the LAA. The right atrium (RA) was targeted in patients with a right-to-left gradient in cycle length (CL). The end point of appendage ablation was CL slowing or AF termination but not complete isolation. RESULTS: Among the 113 patients (mean age 64.6 ± 8.6 years; ejection fraction 54% ± 13%; LA diameter 46 ± 6.5 mm), radiofrequency ablation terminated AF in 51 patients (45%). RA ablation was performed in 41 patients (36%) at the index or repeat procedure. The mean AF CL in the RA appendage (RAA) was shorter than that in the LAA (160 ± 32 ms vs 186 ± 29 ms; P < .01) in these patients. The most frequent target in the RA was the RAA (CLs approaching 50-60 ms). Discontinuing radiofrequency ablation upon AF termination or conduction slowing prevented LAA isolation. After a mean follow-up of 24 ± 15 months, 89 patients (78%) remained arrhythmia-free without antiarrhythmic medications. CONCLUSION: An ablation strategy guided by the AF CL addresses LAA drivers without complete electrical isolation and also helps identify the RAA as a source of persistent AF.

Long-Term Prognosis of Patients With Coronary Microvascular Disease Using Stress Perfusion Cardiac Magnetic Resonance.

OBJECTIVES: This study investigated the prognosis of coronary microvascular disease (CMD) as determined by stress perfusion cardiac magnetic resonance (CMR) in patients with ischemic symptoms but without significant coronary artery disease (CAD). BACKGROUND: Patients with CMD have poorer prognosis with various cardiac diseases. The myocardial perfusion reserve index (MPRI) derived from noninvasive stress perfusion CMR has been established to diagnose microvascular angina with a threshold MPRI <1.4. The prognosis of CMD as determined by MPRI is unknown. METHODS: Chest pain patients without epicardial CAD or myocardial disease from January 2009 to December 2017 were retrospectively included from 3 imaging centers in Hong Kong (HK). Stress perfusion CMR examinations were performed using either adenosine or adenosine triphosphate. Adequate stress was assessed by achieving splenic switch-off sign. Measurement of MPRI was performed in all stress perfusion CMR scans. Patients were followed for major adverse cardiovascular events defined as all-cause death, acute coronary syndrome (ACS), epicardial CAD development, heart failure hospitalization and non-fatal stroke. RESULTS: A total of 218 patients were studied (mean age 59 ± 12 years; 49.5% male) and the average MPRI of that cohort was 1.56 ± 0.33. Females and a history of hyperlipidemia were predictors of lower MPRI. Major adverse cardiovascular events (MACE) occurred in 15.6% of patients during a median follow-up of 5.5 years (interquartile range: 4.6 to 6.8 years). The optimal cutoff value of MPRI in predicting MACE was found with a threshold MPRI ≤1.47. Patients with MPRI ≤1.47 had three-fold increased risk of MACE compared with those with MPRI >1.47 (hazard ratio [HR]: 3.14; 95% confidence interval [CI]: 1.58 to 6.25; p = 0.001). Multivariate Cox regression after adjusting for age and hypertension demonstrated that MPRI was an independent predictor of MACE (HR: 0.10; 95% CI: 0.03 to 0.34; p < 0.001). CONCLUSIONS: Stress perfusion CMR-derived MPRI is an independent imaging marker that predicts MACE in patients with ischemic symptom and no overt CAD over the medium term.