Lipomatous Metaplasia Is Associated With Ventricular Tachycardia Recurrence Following Ablation in Patients With Nonischemic Cardiomyopathy.

BACKGROUND: Ventricular tachycardia (VT) recurrence rates remain high following ablation among patients with nonischemic cardiomyopathy (NICM). OBJECTIVES: This study sought to define the prevalence of lipomatous metaplasia (LM) in patients with NICM and VT and its association with postablation VT recurrence. METHODS: From patients who had ablation of left ventricular VT, we retrospectively identified 113 consecutive NICM patients with preprocedural contrast-enhanced cardiac computed tomography (CECT), from which LM was segmented. Nested within this cohort were 62 patients that prospectively underwent CECT and cardiac magnetic resonance from which myocardial border zone and dense late gadolinium enhancement (LGE) were segmented. A control arm of 30 NICM patients without VT with CECT was identified. RESULTS: LM was identified among 57% of control patients without VT vs 83% of patients without VT recurrence and 100% of patients with VT recurrence following ablation. In multivariable analyses, LM extent was the only independent predictor of VT recurrence, with an adjusted HR per 1-g LM increase of 1.1 (P < 0.001). Patients with LM extent ≥2.5 g had 4.9-fold higher hazard of VT recurrence than those with LM <2.5 g (P < 0.001). In the nested cohort with 32 VT recurrences, LM extent was independently associated with VT recurrence after adjustment for border zone and LGE extent (HR per 1 g increase: 1.1; P = 0.036). CONCLUSIONS: Myocardial LM is prevalent in patients with NICM of a variety of etiologies, and its extent is associated with postablation VT recurrence independent of the degree of fibrosis.

Pulmonary Vein Isolation With or Without Left Atrial Appendage Ligation in Atrial Fibrillation: The aMAZE Randomized Clinical Trial.

Importance: Left atrial appendage elimination may improve catheter ablation outcomes for atrial fibrillation. Objective: To assess the safety and effectiveness of percutaneous left atrial appendage ligation adjunctive to catheter pulmonary vein isolation for nonparoxysmal atrial fibrillation. Design, Setting, and Participants: This multicenter, prospective, open-label, randomized clinical trial evaluated the safety and effectiveness of percutaneous left atrial appendage ligation adjunctive to planned pulmonary vein isolation for nonparoxysmal atrial fibrillation present for less than 3 years. Eligible patients were randomized in a 2:1 ratio to undergo left atrial appendage ligation and pulmonary vein isolation or pulmonary vein isolation alone. Use of a 2:1 randomization ratio was intended to provide more device experience and safety data. Patients were enrolled from October 2015 to December 2019 at 53 US sites, with the final follow-up visit on April 21, 2021. Interventions: Left atrial appendage ligation plus pulmonary vein isolation compared with pulmonary vein isolation alone. Main Outcomes and Measures: A bayesian adaptive analysis was used for primary end points. Primary effectiveness was freedom from documented atrial arrythmias of greater than 30 seconds duration 12 months after undergoing pulmonary vein isolation. Rhythm was assessed by Holter monitoring at 6 and 12 months after pulmonary vein isolation, symptomatic event monitoring, or any electrocardiographic tracing obtained through 12 months after pulmonary vein isolation. Primary safety was a composite of predefined serious adverse events compared with a prespecified 10% performance goal 30 days after the procedure. Left atrial appendage closure was evaluated through 12 months after pulmonary vein isolation. Results: Overall, 404 patients were randomized to undergo left atrial appendage ligation plus pulmonary vein isolation and 206 were randomized to undergo pulmonary vein isolation alone. Primary effectiveness was 64.3% with left atrial appendage ligation and pulmonary vein isolation and 59.9% with pulmonary vein isolation only (difference, 4.3% [bayesian 95% credible interval, -4.2% to 13.2%]; posterior superiority probability, 0.835), which did not meet the statistical criterion to establish superiority (0.977). Primary safety was met, with a 30-day serious adverse event rate of 3.4% (bayesian 95% credible interval, 2.0% to 5.0%; posterior probability, 1.0) which was less than the prespecified threshold of 10%. At 12 months after pulmonary vein isolation, complete left atrial appendage closure (0 mm residual communication) was observed in 84% of patients and less than or equal to 5 mm residual communication was observed in 99% of patients. Conclusions and Relevance: Percutaneous left atrial appendage ligation adjunctive to pulmonary vein isolation did not meet prespecified efficacy criteria for freedom from atrial arrhythmias at 12 months compared with pulmonary vein isolation alone for patients with nonparoxysmal atrial fibrillation, but met prespecified safety criteria and demonstrated high rates of closure at 12 months. Trial Registration: ClinicalTrials.gov Identifier: NCT02513797.

Pericarditis After Catheter Ablation for Atrial Fibrillation: Predictors and Outcomes.

BACKGROUND: Catheter ablation is a mainstay of atrial fibrillation (AF) treatment. Acute pericarditis after ablation is 1 of the frequently observed complications. There is a significant lack of data on the incidence and predictors of postablation pericarditis. OBJECTIVES: This study examines the incidence, characteristics, and predictors of pericarditis after AF ablation. METHODS: Patients undergoing AF ablation from January 1, 2016, to March 31, 2022, at Johns Hopkins were prospectively enrolled in an AF ablation registry. A clinical diagnosis of acute pericarditis was established in accordance with 2015 European Society of Cardiology guidelines by the presence of at least 2 of the following characteristics: pleuritic chest pain, friction rub, typical electrocardiographic changes, or pericardial effusion within 3 months after the ablation procedure. RESULTS: Of 1,540 patients who underwent AF ablation, 57 patients (3.7%) developed acute pericarditis. Baseline clinical characteristics including age, sex, and body mass index were comparable between the pericarditis and nonpericarditis groups. The median time to symptom onset was 1 day. Electrocardiographic changes were observed in 34 (59.6%) patients, pericardial effusion developed in 7 (12%) patients, and the mean duration of medical treatment was 7 days (25th-75th percentile: 3-14 days). Most pericarditis cases were treated medically with disease-specific nonsteroidal anti-inflammatory drugs (100%) and colchicine (81%). Effusion with tamponade necessitating pericardiocentesis was observed in 4 (7%) patients. Radiofrequency (RF) ablation was performed in 869 (58.6%) patients in the nonpericarditis group and 39 (68.4%) patients with pericarditis; cryoballoon ablation was performed in 486 (32.8%) patients in the nonpericarditis group and 11 (19.3%) patients with pericarditis. Multivariable logistic regression analysis identified RF ablation (OR: 2.09; 95% CI: 1.07-4.08; P = 0.03) as an independent predictor of acute pericarditis after AF ablation, whereas age per unit increase was associated with a decreased risk (OR: 0.97; 95% CI: 0.95-0.995; P = 0.02). CONCLUSIONS: The incidence of acute pericarditis after catheter ablation in our study population was 3.7%. RF ablation and younger age were independent risk factors for postablation acute pericarditis.

Conduction Velocity Dispersion Predicts Postinfarct Ventricular Tachycardia Circuit Sites and Associates With Lipomatous Metaplasia.

BACKGROUND: Regional myocardial conduction velocity (CV) dispersion has not been studied in postinfarct patients with ventricular tachycardia (VT). OBJECTIVES: This study sought to compare the following: 1) the association of CV dispersion vs repolarization dispersion with VT circuit sites; and 2) myocardial lipomatous metaplasia (LM) vs fibrosis as the anatomic substrate for CV dispersion. METHODS: Among 33 postinfarct patients with VT, we characterized dense and border zone infarct tissue by late gadolinium enhancement cardiac magnetic resonance, and LM by computed tomography, with both images registered with electroanatomic maps. Activation recovery interval (ARI) was the time interval from the minimum derivative within the QRS complex to the maximum derivative within the T-wave on unipolar electrograms. CV at each EAM point was the mean CV between that point and 5 adjacent points along the activation wave front. CV and ARI dispersion were the coefficient of variation (CoV) of CV and ARI per American Heart Association (AHA) segment, respectively. RESULTS: Regional CV dispersion exhibited a much larger range than ARI dispersion, with median 0.65 vs 0.24; P < 0.001. CV dispersion was a more robust predictor of the number of critical VT sites per AHA segment than ARI dispersion. Regional LM area was more strongly associated with CV dispersion than fibrosis area. LM area was larger (median 0.44 vs 0.20 cm2; P < 0.001) in AHA segments with mean CV <36 cm/s and CoV_CV >0.65 than those with mean CV <36 cm/s and CoV_CV <0.65. CONCLUSIONS: Regional CV dispersion more strongly predicts VT circuit sites than repolarization dispersion, and LM is a critical substrate for CV dispersion.

Decreased Cardiac Autonomic Function is Associated with Higher Exacerbation Risk and Symptom Burden in Chronic Obstructive Pulmonary Disease.

Current measures of chronic obstructive pulmonary disease (COPD) severity, including lung function, do not fully explain symptom burden, and there is a need to identify predictors of exacerbation risk and morbidity. Autonomic dysfunction may be implicated in both cardiovascular and respiratory morbidity in COPD and convey risk for exacerbations. Heart rate variability (HRV) is a marker of cardiac autonomic function that is predictive of cardiovascular health and has promise as a non-invasive COPD biomarker. The CLEAN AIR Heart study provided an opportunity to investigate the association between HRV and COPD morbidity among former smokers with moderate-severe COPD. Eighty-five participants, contributing 305 HRV measurements, underwent repeated clinical assessments over 4 study periods that included a 24-Holter monitoring assessment of HRV. HRV measures of interest were standard deviation of normal-to-normal intervals, (SDNN) (overall HRV) and root-mean-square of successive differences (RMSSD) (parasympathetic function). Exacerbation risk was assessed using negative binomial models, and mixed-effects models analyzed associations between HRV and symptoms. Decreases in SDNN (incidence rate ratio [IRR]1.40; 95% confidence interval [CI] 1.13 to1.74) and RMSSD (IRR 1.60; 95% CI 1.07 to 2.37) were associated with severe exacerbation risk. Decreases in SDNN were associated with higher St George's Respiratory Questionnaire scores, COPD Assessment Test scores, and chronic bronchitis symptoms. Findings demonstrate that HRV is associated with COPD symptom burden and exacerbation risk. HRV may represent an important biomarker with the potential to identify high-risk COPD populations.

Sex-based differences in safety and efficacy of catheter ablation for atrial fibrillation.

BACKGROUND: Studies have identified significant sex-based differences and disparities in the clinical presentation and treatment of atrial fibrillation (AF). Studies have shown women are less likely to be referred for catheter ablation, are older at the time of ablation, and are more likely to have recurrence after ablation. However, in most studies investigating AF ablation outcomes, the female cohorts were relatively small. The impact of sex on the outcome and safety of ablation procedures is still unclear. OBJECTIVE: To investigate sex-based differences in outcomes and complications after AF catheter ablation, with a significant female cohort METHOD: In this retrospective study, patients undergoing AF ablation from January 1, 2014, to March 31, 2021, were included. We investigated clinical characteristics, duration and progression of AF, number of EP appointments from diagnosis to ablation, procedural data, and procedure complications. RESULTS: Total of 1346 patients underwent first catheter ablation for AF during this period, including 896 (66.5%) male and 450 (33.4%) female patients. Female patients were older at the time of ablation (66.2 vs. 62.4 years; p < .001). Women had higher CHA2 DS2 -VASc (congestive heart failure, hypertension, age, diabetes, stroke, vascular disease, sex category) scores (3 vs. 2; p < .001) than men, expectedly, as the female sex warrants an additional point. 25.3% female patients had PersAF at the time of diagnosis versus 35.3% male patients (p < .001). At the time of ablation, 31.8% female patients had PersAF as compared to 43.1% male patients (p < .001), indicating progression of PAF to PersAF in both sexes. Women tried more AADs than men before ablation (1.13 vs. 0.98; p = .002). Male and female patients had no statistically significant difference in (a) arrhythmia recurrence at 1-year post ablation (27.7% vs. 30%; p = .38) or (b) procedural complication rate (1.8% vs. 3.1%; p = .56). CONCLUSION: Female patients were older and had higher CHA2 DS2 -VASc scores compared to males at the time of AF ablation. Women tried more AADs than men before ablation. One-year arrhythmia recurrence rates and procedural complications were similar in both sexes. No sex-based differences were observed in safety and efficacy of ablation.

Lipomatous Metaplasia Facilitates Slow Conduction in Critical Ventricular Tachycardia Corridors Within Postinfarct Myocardium.

BACKGROUND: Myocardial lipomatous metaplasia (LM) has been reported to be associated with post-infarct ventricular tachycardia (VT) circuitry. OBJECTIVES: This study examined the association of scar versus LM composition with impulse conduction velocity (CV) in putative VT corridors that traverse the infarct zone in post-infarct patients. METHODS: The cohort included 31 post-infarct patients from the prospective INFINITY (Intra-Myocardial Fat Deposition and Ventricular Tachycardia in Cardiomyopathy) study. Myocardial scar, border zone, and potential viable corridors were defined by late gadolinium enhancement cardiac magnetic resonance (LGE-CMR), and LM was defined by computed tomography. Images were registered to electroanatomic maps, and the CV at each electroanatomic map point was calculated as the mean CV between that point and 5 adjacent points along the activation wave front. RESULTS: Regions with LM exhibited lower CV than scar (median = 11.9 vs 13.5 cm/s; P < 0.001). Of 94 corridors computed from LGE-CMR and electrophysiologically confirmed to participate in VT circuitry, 93 traversed through or near LM. These critical corridors displayed slower CV (median 8.8 [IQR: 5.9-15.7] cm/s vs 39.2 [IQR: 28.1-58.5]) cm/s; P < 0.001) than 115 noncritical corridors distant from LM. Additionally, critical corridors demonstrated low-peripheral, high-center (mountain shaped, 23.3%) or mean low-level (46.7%) CV patterns compared with 115 noncritical corridors distant from LM that displayed high-peripheral, low-center (valley shaped, 19.1%) or mean high-level (60.9%) CV patterns. CONCLUSIONS: The association of myocardial LM with VT circuitry is at least partially mediated by slowing nearby corridor CV thus facilitating an excitable gap that enables circuit re-entry.

Trends in the Use and Complications of Cardiac Resynchronization Therapy Device Implantation in Chronic Kidney Disease Patients.

Large-scale multi-hospital data on cardiac resynchronization therapy (CRT) device implantation in patients with chronic kidney disease (CKD) are currently lacking. The purpose of this study was to examine the incidence of CRT device implantation in patients hospitalized with CKD and the impact of CRT device implantation on hospital complications and outcomes. We analyzed the Nationwide Inpatient Sample from 2008-2014 to identify yearly trends in CRT device implantation during CKD hospitalizations. We compared CRT biventricular pacemakers (CRT-Ps) and CRT defibrillators (CRT-Ds). We also obtained rates of comorbidities and complications associated with CRT device implantations. From 2008-2014, the proportion of hospitalized patients with a concurrent diagnosis of CKD receiving CRT-P devices consistently went up from 2008 to 2014 (from 12.3% to 23.8%, P < .0001) compared to the number of hospitalized patients with a concurrent diagnosis of CKD receiving CRT-D devices, which showed a consistent downward trend (from 87.7% to 76.2%, P < .0001). During CKD hospitalizations, most CRT device implantations were performed in patients aged 65-84 years (68.6%) and in men (74.3%). The most common complication of CRT device implantation during hospitalizations involving CKD was hemorrhage or hematoma (2.7%). Patients hospitalized with CKD who developed any complication associated with CRT device implantation had 3.35-fold increased odds of mortality compared to those without complications (odds ratio, 3.35; 95% confidence interval, 2.18-5.16; P < .0001). In summary, this study shows that CRT-P implantations became more common in CKD patients, while the rate of CRT-D implantations decreased over time. Hemorrhage or hematoma was the most common complication (2.7%), and the mortality risk was increased by 3.35 times in patients who developed periprocedural complications.

Relationship between amiodarone response prior to ablation and 1-year outcomes of catheter ablation for atrial fibrillation.

INTRODUCTION: Catheter ablation for atrial fibrillation (AF) is a common therapeutic strategy for patients with either paroxysmal AF (PAF) or persistent AF (persAF), but long-term ablation success rates are imperfect. Maintenance of sinus rhythm immediately before ablation with antiarrhythmic drug (AAD) therapy has been associated with improved outcomes in patients undergoing ablation. Amiodarone has superior efficacy relative to other AADs. Whether failure of amiodarone to maintain sinus rhythm before ablation for either PAF or persAF is associated with poor outcomes is unknown. METHODS: A total of 307 patients who received amiodarone in a 1-year window before undergoing catheter ablation for AF were included. Patients were divided into amiodarone success (n = 183) and amiodarone failure (n = 124) groups based on the response to pre-ablation amiodarone treatment. Analysis of procedural outcomes as a function of response to amiodarone therapy was performed. Patients were followed for at least 12 months postablation, to assess outcomes (adverse events and arrhythmia recurrence). Procedural success was defined by the absence of documented arrhythmia (>30 s) without any antiarrhythmic agents beyond a 90-day blanking period. RESULTS: Following ablation for either PAF or persAF, freedom from any recurrent atrial arrhythmia at 1 year was 57.7% for the entire cohort. One-year freedom from recurrent arrhythmia in the amiodarone success group was comparable to that in the amiodarone failure group (55.7% vs. 60.5%; p = .54). Success rates following ablation did not vary by the response to amiodarone when analyzed for PAF or persAF subgroups. CONCLUSION: Failure to restore and maintain sinus rhythm with amiodarone before ablation for either PAF or persAF is not a predictor of ablation procedural failure. Amiodarone failure alone should not deter practitioners from considering ablation therapy for patients with AF.

Lipomatous metaplasia prolongs repolarization and increases repolarization dispersion within post-infarct ventricular tachycardia circuit cites.

AIMS: Post-infarct myocardium contains viable corridors traversing scar or lipomatous metaplasia (LM). Ventricular tachycardia (VT) circuitry has been separately reported to associate with corridors that traverse LM and with repolarization heterogeneity. We examined the association of corridor activation recovery interval (ARI) and ARI dispersion with surrounding tissue type. METHODS AND RESULTS: The cohort included 33 post-infarct patients from the prospective Intra-Myocardial Fat Deposition and Ventricular Tachycardia in Cardiomyopathy (INFINITY) study. We co-registered scar and corridors from late gadolinium enhanced magnetic resonance, and LM from computed tomography with intracardiac electrogram locations. Activation recovery interval was calculated during sinus or ventricular pacing, as the time interval from the minimum derivative within the QRS to the maximum derivative within the T-wave on unipolar electrograms. Regional ARI dispersion was defined as the standard deviation (SD) of ARI per AHA segment (ARISD). Lipomatous metaplasia exhibited higher ARI than scar [325 (interquartile range 270-392) vs. 313 (255-374), P < 0.001]. Corridors critical to VT re-entry were more likely to traverse through or near LM and displayed prolonged ARI compared with non-critical corridors [355 (319-397) vs. 302 (279-333) ms, P < 0.001]. ARISD was more closely associated with LM than with scar (likelihood ratio χ2 50 vs. 12, and 4.2-unit vs. 0.9-unit increase in 0.01*Log(ARISD) per 1 cm2 increase per AHA segment). Additionally, LM and scar exhibited interaction (P < 0.001) in their association with ARISD. CONCLUSION: Lipomatous metaplasia is closely associated with prolonged local action potential duration of corridors and ARI dispersion, which may facilitate the propensity of VT circuit re-entry.

Indoor Air Pollution and Impaired Cardiac Autonomic Function in Chronic Obstructive Pulmonary Disease.

Rationale: Indoor air pollution represents a modifiable risk factor for respiratory morbidity in chronic obstructive pulmonary disease (COPD). The effects of indoor air pollution, as well as the impact of interventions to improve indoor air quality, on cardiovascular morbidity in COPD remain unknown. Objectives: To determine the association between indoor particulate matter (PM) and heart rate variability (HRV), a measure of cardiac autonomic function tied to cardiovascular morbidity and mortality, as well as the impact of household air purifiers on HRV. Methods: Former smokers with moderate-severe COPD were recruited from a 6-month randomized controlled trial of a portable air cleaner intervention to undergo paired assessment of both in-home PM and HRV using 24-hour Holter monitoring at up to five time points. Primary outcomes were HRV measures tied to cardiovascular morbidity (standard deviation of normal-to-normal intervals [SDNN] and root mean square of successive differences between normal-to-normal intervals [RMSSD]). Measurements and Results: Eighty-five participants contributed 317 HRV measurements. A twofold increase in household PM ⩽2.5 µm in aerodynamic diameter was associated with decreases in SDNN (ß, -2.98% [95% confidence interval (CI), -5.12 to -0.78]) and RMSSD (ß, -4.57% [95% CI, -10.1 to -1.60]). The greatest effects were observed with ultrafine particles (<100 nm) (RMSSD; ß, -16.4% [95% CI, -22.3 to -10.1]) and among obese participants. Participants randomized to the active air cleaner saw improvements in RMSSD (ß, 25.2% [95% CI, 2.99 to 52.1]), but not SDNN (ß, 2.65% [95% CI, -10.8 to 18.1]), compared with the placebo group. Conclusions: This is the first U.S. study to describe the association between household PM and cardiac autonomic function among individuals with COPD, as well as the potential cardiovascular health benefits of household air cleaners.

Wavefront directionality and decremental stimuli synergistically improve identification of ventricular tachycardia substrate: insights from personalized computational heart models.

AIMS: Multiple wavefront pacing (MWP) and decremental pacing (DP) are two electroanatomic mapping (EAM) strategies that have emerged to better characterize the ventricular tachycardia (VT) substrate. The aim of this study was to assess how well MWP, DP, and their combination improve identification of electrophysiological abnormalities on EAM that reflect infarct remodelling and critical VT sites. METHODS AND RESULTS: Forty-eight personalized computational heart models were reconstructed using images from post-infarct patients undergoing VT ablation. Paced rhythms were simulated by delivering an initial (S1) and an extra-stimulus (S2) from one of 100 locations throughout each heart model. For each pacing, unipolar signals were computed along the myocardial surface to simulate substrate EAM. Six EAM features were extracted and compared with the infarct remodelling and critical VT sites. Concordance of S1 EAM features between different maps was lower in hearts with smaller amounts of remodelling. Incorporating S1 EAM features from multiple maps greatly improved the detection of remodelling, especially in hearts with less remodelling. Adding S2 EAM features from multiple maps decreased the number of maps required to achieve the same detection accuracy. S1 EAM features from multiple maps poorly identified critical VT sites. However, combining S1 and S2 EAM features from multiple maps paced near VT circuits greatly improved identification of critical VT sites. CONCLUSION: Electroanatomic mapping with MWP is more advantageous for characterization of substrate in hearts with less remodelling. During substrate EAM, MWP and DP should be combined and delivered from locations proximal to a suspected VT circuit to optimize identification of the critical VT site.

Lipomatous Metaplasia Enables Ventricular Tachycardia by Reducing Current Loss Within the Protected Corridor.

BACKGROUND: Post-myocardial infarction ventricular tachycardia (VT) is due to re-entry through surviving conductive myocardial corridors across infarcted tissue. However, not all conductive corridors participate in re-entry. OBJECTIVES: This study sought to test the hypothesis that critical VT corridors are more likely to traverse near lipomatous metaplasia (LM) and that current loss is reduced during impulse propagation through such corridors. METHODS: Among 30 patients in the Prospective 2-center INFINITY (Intra-Myocardial Fat Deposition and Ventricular Tachycardia in Cardiomyopathy) study, potential VT-viable corridors within myocardial scar or LM were computed from late gadolinium enhancement cardiac magnetic resonance images. Because late gadolinium enhancement highlights both scar and LM, LM was distinguished from scar by using computed tomography. The SD of the current along each corridor was measured. RESULTS: Scar exhibited lower impedance than LM (median Z-score -0.22 [IQR: -0.84 to 0.35] vs -0.07 [IQR: -0.67 to 0.54]; P < 0.001). Among all 381 corridors, 84 were proven to participate in VT re-entry circuits, 83 (99%) of which traversed or were adjacent to LM. In comparison, only 13 (4%) non-VT corridors were adjacent to LM. Critical corridors adjacent to LM displayed lower SD of current compared with noncritical corridors through scar but distant from LM (2.0 [IQR: 1.0 to 3.4] µA vs 8.4 [IQR: 5.5 to 12.8] µA; P < 0.001). CONCLUSIONS: Corridors critical to VT circuitry traverse infarcted tissue through or near LM. This association is likely mediated by increased regional resistance and reduced current loss as impulses traverse corridors adjacent to LM.

The Virtual Inclusive Digital Health Intervention Design to Promote Health Equity (iDesign) Framework for Atrial Fibrillation: Co-design and Development Study.

BACKGROUND: Smartphone ownership and mobile app use are steadily increasing in individuals of diverse racial and ethnic backgrounds living in the United States. Growing adoption of technology creates a perfect opportunity for digital health interventions to increase access to health care. To successfully implement digital health interventions and engage users, intervention development should be guided by user input, which is best achieved by the process of co-design. Digital health interventions co-designed with the active engagement of users have the potential to increase the uptake of guideline recommendations, which can reduce morbidity and mortality and advance health equity. OBJECTIVE: We aimed to co-design a digital health intervention for patients with atrial fibrillation, the most common cardiac arrhythmia, with patient, caregiver, and clinician feedback and to describe our approach to human-centered design for building digital health interventions. METHODS: We conducted virtual meetings with patients with atrial fibrillation (n=8), their caregivers, and clinicians (n=8). We used the following 7 steps in our co-design process: step 1, a virtual meeting focused on defining challenges and empathizing with problems that are faced in daily life by individuals with atrial fibrillation and clinicians; step 2, a virtual meeting focused on ideation and brainstorming the top challenges identified during the first meeting; step 3, individualized onboarding of patients with an existing minimally viable version of the atrial fibrillation app; step 4, virtual prototyping of the top 3 ideas generated during ideation; step 5, further ranking by the study investigators and engineers of the ideas that were generated during ideation but were not chosen as top-3 solutions to be prototyped in step 4; step 6, ongoing engineering work to incorporate top-priority features in the app; and step 7, obtaining further feedback from patients and testing the atrial fibrillation digital health intervention in a pilot clinical study. RESULTS: The top challenges identified by patients and caregivers included addressing risk factor modification, medication adherence, and guidance during atrial fibrillation episodes. Challenges identified by clinicians were complementary and included patient education, addressing modifiable atrial fibrillation risk factors, and remote atrial fibrillation episode management. Patients brainstormed more than 30 ideas to address the top challenges, and the clinicians generated more than 20 ideas. Ranking of the ideas informed several novel or modified features aligned with the Theory of Health Behavior Change, features that were geared toward risk factor modification; patient education; rhythm, symptom, and trigger correlation for remote atrial fibrillation management; and social support. CONCLUSIONS: We co-designed an atrial fibrillation digital health intervention in partnership with patients, caregivers, and clinicians by virtually engaging in collaborative creation through the design process. We summarize our experience and describe a flexible approach to human-centered design for digital health intervention development that can guide innovative clinical investigators.

Radiographic Identification of Cardiac Implantable Electronic Device Manufacturer: Smartphone Pacemaker-ID Application Versus X-ray Logo.

Radiographic identification of the cardiac implantable electronic device (CIED) manufacturer facilitates urgent interrogation of an unknown CIED. In the past, we relied on visualizing a manufacturer-specific X-ray logo. Recently, a free smartphone application ("Pacemaker-ID") was made available. A photograph of a chest X-ray was subjected to an artificial intelligence (AI) algorithm that uses manufacturer characteristics (canister shape, battery design) for identification. We sought to externally validate the accuracy of this smartphone application as a point-of-care (POC) diagnostic tool, compare on-axis to off-axis photo accuracy, and compare it to X-ray logo visualization for manufacturer identification. We reviewed operative reports and chest X-rays in 156 pacemaker and 144 defibrillator patients to visualize X-ray logos and to test the application with 3 standard (on-axis) and 4 non-standard (off-axis) photos (20° cranial; caudal, leftward, and rightward). Contingency tables were created and chi-squared analyses (P < .05) were completed for manufacturer and CIED type. The accuracy of the application was 91.7% and 86.3% with single and serial application(s), respectively; 80.7% with off-axis photos; and helpful for all manufacturers (range, 85.4%-96.6%). Overall, the application proved superior to the X-ray logo, visualized in 56% overall (P < .0001) but varied significantly by manufacturer (range, 7.7%-94.8%; P < .00001). The accuracy of the Pacemaker-ID application is consistent with reports from its creators and superior to X-ray logo visualization. The accuracy of the application as a POC tool can be enhanced and maintained with further AI training using recent CIED models. Some manufacturers can enhance their X-ray logos by improving placement and design.

Association of left ventricular tissue heterogeneity and intramyocardial fat on computed tomography with ventricular arrhythmias in ischemic cardiomyopathy.

Background: Gray zone, a measure of tissue heterogeneity on late gadolinium enhanced-cardiac magnetic resonance (LGE-CMR) imaging, has been shown to predict ventricular arrhythmias (VAs) in ischemic cardiomyopathy (ICM) patients. However, no studies have described whether left ventricular (LV) tissue heterogeneity and intramyocardial fat mass on contrast-enhanced computed tomography (CE-CT), which provides greater spatial resolution, is useful for assessing the risk of VAs in ICM patients with LV systolic dysfunction and no previous VAs. Objective: The purpose of this proof-of-concept study was to determine the feasibility of measuring global LV tissue heterogeneity and intramyocardial fat mass by CE-CT for predicting the risk of VAs in ICM patients with LV systolic dysfunction and no previous history of VAs. Methods: Patients with left ventricular ejection fraction ≤35% and no previous VAs were enrolled in a prospective, observational registry and underwent LGE-CMR. From this cohort, patients with ICM who additionally received CE-CT were included in the present analysis. Gray zone on LGE-CMR was defined as myocardium with signal intensity (SI) > peak SI of healthy myocardium but <50% maximal SI. Tissue heterogeneity on CE-CT was defined as the standard deviation of the Hounsfield unit image gradients (HU/mm) within the myocardium. Intramyocardial fat on CE-CT was identified as regions of image pixels between -180 and -5 HU. The primary outcome was VAs, defined as appropriate implantable cardioverter-defibrillator shock or sudden arrhythmic death. Results: The study consisted of 47 ICM patients, 13 (27.7%) of whom experienced VA events during mean follow-up of 5.6 ± 3.4 years. Increasing tissue heterogeneity (per HU/mm) was significantly associated with VAs after multivariable adjustment, including for gray zone (odds ratio [OR] 1.22; P = .019). Consistently, patients with tissue heterogeneity values greater than or equal to the median (≥22.2 HU/mm) had >13-fold significantly increased risk of VA events, relative to patients with values lower than the median, after multivariable adjustment that included gray zone (OR 13.13; P = .028). The addition of tissue heterogeneity to gray zone improved prediction of VAs (area under receiver operating characteristic curve increased from 0.815 to 0.876). No association was found between intramyocardial fat mass on CE-CT and VAs (OR 1.00; P = .989). Conclusion: In ICM patients, CE-CT-derived LV tissue heterogeneity was independently associated with VAs and may represent a novel marker useful for risk stratification.