Institutional experience report on the target contouring workflow in the radiotherapy department for stereotactic arrhythmia radioablation delivered on conventional linear accelerators.

PURPOSE: In stereotactic arrhythmia radioablation (STAR), the target is defined using multiple imaging studies and a multidisciplinary team consisting of electrophysiologist, cardiologist, cardiac radiologist, and radiation oncologist collaborate to identify the target and delineate it on the imaging studies of interest. This report describes the workflow employed in our radiotherapy department to transfer the target identified based on electrophysiology and cardiology imaging to the treatment planning image set. METHODS: The radiotherapy team was presented with an initial target in cardiac axes orientation, contoured on a wideband late gadolinium-enhanced (WB-LGE) cardiac magnetic resonance (CMR) study, which was subsequently transferred to the computed tomography (CT) scan used for treatment planning-i.e., the average intensity projection (AIP) image set derived from a 4D CT-via an axial CMR image set, using rigid image registration focused on the target area. The cardiac and the respiratory motion of the target were resolved using ciné-CMR and 4D CT imaging studies, respectively. RESULTS: The workflow was carried out for 6 patients and resulted in an internal target defined in standard anatomical orientation that encompassed the cardiac and the respiratory motion of the initial target. CONCLUSION: An image registration-based workflow was implemented to render the STAR target on the planning image set in a consistent manner, using commercial software traditionally available for radiation therapy.

Abnormal Conduction-Induced Cardiomyopathy: JACC Review Topic of the Week.

Nonischemic cardiomyopathies are a frequent occurrence. The understanding of the mechanism(s) and triggers of these cardiomyopathies have led to improvement and even recovery of left ventricular function. Although chronic right ventricular pacing-induced cardiomyopathy has been recognized for many years, left bundle branch block and pre-excitation have been recently identified as potential reversible causes of cardiomyopathy. These cardiomyopathies share a similar abnormal ventricular propagation that can be recognized by a wide QRS duration with left bundle branch block pattern; thus, we coined the term abnormal conduction-induced cardiomyopathies. Such abnormal propagation results in an abnormal contractility that can only be recognized by cardiac imaging as ventricular dyssynchrony. Appropriate diagnosis and treatment will not only lead to improved left ventricular ejection fraction and functional class, but may also reduce morbidity and mortality. This review presents an update of the mechanisms, prevalence, incidence, and risk factors, as well as their diagnosis and management, while highlighting current gaps of knowledge.

Atypical atrial flutter catheter ablation in the era of high-density mapping.

BACKGROUND: Mapping and ablating atypical atrial flutters (AAFLs) have evolved greatly with advances in high-density 3D mapping systems over the last years. METHODS: The objectives are to evaluate the feasibility of AAFL catheter ablation based on high-density mapping and minimizing entrainment and to better characterize AAFL circuits. Consecutive patients who underwent AAFL ablation using the EnSite Precision™ system and HD Grid™ mapping catheter (Abbott, Chicago, IL) between 06/2018 and 1/2022 were included. Mitral isthmus-dependent and roof-dependent AAFLs were classified as conventional circuits. All other AAFL circuits were classified as non-conventional circuits and were defined based on the location of the critical isthmus. RESULTS: Sixty-two patients underwent AAFL ablation (mean age 68±11 years). A total of 95 AAFLs were mapped and 92 (97%) were successfully ablated. Fifty-three (85%) patients had a previous AF/AFL ablation. Forty-four (46%) AAFL circuits were classified as conventional and 51 (54%) as non-conventional. Conventional AAFL circuits had longer critical isthmuses (19.0±9.0 vs 10.8±6.3mm, p<0.001), a lower prevalence of slow conduction at the critical isthmus (59% vs 86%, p=0.005), and a longer radiofrequency time to AAFL termination (117±119 vs 51±66 s, p=0.002). Entrainment was attempted in 19 (20%) flutters and its use declined significantly over the study period. Procedural success rates remained high whether entrainment was used or not. Freedom of any atrial tachycardia was 65% over a follow-up of 13.8±9.0 months. CONCLUSIONS: AAFL catheter ablation can be achieved with high procedural success rate using a contemporary strategy based on high-density mapping alone. Non-conventional circuits are frequent and present unique electrophysiological characteristics.

Outcomes Associated With Catheter Ablation of Ventricular Tachycardia in Patients With Cardiac Sarcoidosis.

Importance: Ventricular tachycardia (VT) is associated with high mortality in patients with cardiac sarcoidosis (CS), and medical management of CS-associated VT is limited by high failure rates. The role of catheter ablation has been investigated in small, single-center studies. Objective: To investigate outcomes associated with VT ablation in patients with CS. Design, Setting, and Participants: This cohort study from the Cardiac Sarcoidosis Consortium registry (2003-2019) included 16 tertiary referral centers in the US, Europe, and Asia. A total of 158 consecutive patients with CS and VT were included (33% female; mean [SD] age, 52 [11] years; 53% with ejection fraction [EF] <50%). Exposures: Catheter ablation of CS-associated VT and, as appropriate, medical treatment. Main Outcomes and Measures: Immediate and short-term outcomes included procedural success, elimination of VT storm, and reduction in defibrillator shocks. The primary long-term outcome was the composite of VT recurrence, heart transplant (HT), or death. Results: Complete procedural success (no inducible VT postablation) was achieved in 85 patients (54%). Sixty-five patients (41%) had preablation VT storm that did not recur postablation in 53 (82%). Defibrillator shocks were significantly reduced from a median (IQR) of 2 (1-5) to 0 (0-0) in the 30 days before and after ablation (P < .001). During median (IQR) follow-up of 2.5 (1.1-4.9) years, 73 patients (46%) experienced VT recurrence and 81 (51%) experienced the composite primary outcome. One- and 2-year rates of survival free of VT recurrence, HT, or death were 60% and 52%, respectively. EF less than 50% and myocardial inflammation on preprocedural 18F-fluorodeoxyglucose positron emission tomography were significantly associated with adverse prognosis in multivariable analysis for the primary outcome (HR, 2.24; 95% CI, 1.37-3.64; P = .001 and HR, 2.93; 95% CI, 1.31-6.55; P = .009, respectively). History of hypertension was associated with a favorable long-term outcome (adjusted HR, 0.51; 95% CI, 0.28-0.92; P = .02). Conclusions and Relevance: In this observational study of selected patients with CS and VT, catheter ablation was associated with reductions in defibrillator shocks and recurrent VT storm. Preablation LV dysfunction and myocardial inflammation were associated with adverse long-term prognosis. These data support the role of catheter ablation in conjunction with medical therapy in the management of CS-associated VT.

Persistent Proarrhythmic Neural Remodeling Despite Recovery From Premature Ventricular Contraction-Induced Cardiomyopathy.

BACKGROUND: The presence and significance of neural remodeling in premature ventricular contraction-induced cardiomyopathy (PVC-CM) remain unknown. OBJECTIVES: This study aimed to characterize cardiac sympathovagal balance and proarrhythmia in a canine model of PVC-CM. METHODS: In 12 canines, the investigators implanted epicardial pacemakers and radiotelemetry units to record cardiac rhythm and nerve activity (NA) from the left stellate ganglion (SNA), left cardiac vagus (VNA), and arterial blood pressure. Bigeminal PVCs (200 ms coupling) were applied for 12 weeks to induce PVC-CM in 7 animals then disabled for 4 weeks to allow complete recovery of left ventricular ejection fraction (LVEF), versus 5 sham controls. RESULTS: After 12 weeks of PVCs, LVEF (p = 0.006) and dP/dT (p = 0.007) decreased. Resting SNA (p = 0.002) and VNA (p = 0.04), exercise SNA (p = 0.01), SNA response to evoked PVCs (p = 0.005), heart rate (HR) at rest (p = 0.003), and exercise (p < 0.04) increased, whereas HR variability (HRV) decreased (p = 0.009). There was increased spontaneous atrial (p = 0.02) and ventricular arrhythmias (p = 0.03) in PVC-CM. Increased SNA preceded both atrial (p = 0.0003) and ventricular (p = 0.009) arrhythmia onset. Clonidine suppressed SNA and abolished all arrhythmias. After disabling PVC for 4 weeks, LVEF (p = 0.01), dP/dT (p = 0.047), and resting VNA (p = 0.03) recovered to baseline levels. However, SNA, resting HR, HRV, and atrial (p = 0.03) and ventricular (p = 0.03) proarrhythmia persisted. There was sympathetic hyperinnervation in stellate ganglia (p = 0.02) but not ventricles (p = 0.2) of PVC-CM and recovered animals versus sham controls. CONCLUSIONS: Neural remodeling in PVC-CM is characterized by extracardiac sympathetic hyperinnervation and sympathetic neural hyperactivity that persists despite normalization of LVEF. The altered cardiac sympathovagal balance is an important trigger and substrate for atrial and ventricular proarrhythmia.

Cardiac Sarcoidosis.

PURPOSE OF REVIEW: In this state-of-the-art review, we highlight our current understanding of diagnosis, assessment, and management of cardiac sarcoidosis (CS), focusing on recently published data and expert consensus statement guidelines. RECENT FINDINGS: Academic interest in cardiac sarcoidosis research has increased over the past decade along with increased clinical awareness among clinicians. In 2014, the Heart Rhythm Society published the first expert consensus statement on diagnosing and managing arrhythmias associated with CS. Cardiac magnetic resonance has emerged as a valuable tool both for diagnosing CS and predicting risk of life-threatening ventricular arrhythmias based on burden of late gadolinium enhancement. Cardiac fluorodeoxyglucose-positron emission tomography now plays a role in diagnosis, risk stratification, and assessing response to immunosuppressive therapy. Collaborative, multidisciplinary research efforts are needed to further our understanding of this rare, complex disease. Two large multicenter prospective registries-the international Cardiac Sarcoidosis Consortium and the Canadian Cardiac Sarcoidosis Research Group-are enrolling patients to help provide insights into the natural history of the disease and current treatment strategies. Future research should focus on randomized controlled trials comparing different treatment strategies and identifying and testing novel therapeutic agents.

Antiarrhythmic Drugs: Risks and Benefits.

The narrow therapeutic window of antiarrhythmic drugs makes their use clinically challenging. A solid understanding of the mechanisms of arrhythmias and how antiarrhythmics affect these mechanisms is only a preliminary step in their appropriate selection. Clinical factors, side-effect profiles, and proarrhythmic risks are more important than the cellular mechanisms of actions in drug selection and monitoring. This article provides a simplified approach to understanding cellular mechanisms and provides a practical approach to the selection and use of this important class of medications.

Interleukin-1 Blockade in Recently Decompensated Systolic Heart Failure: Results From REDHART (Recently Decompensated Heart Failure Anakinra Response Trial).

BACKGROUND: An enhanced inflammatory response predicts worse outcomes in heart failure (HF). We hypothesized that administration of IL-1 (interleukin-1) receptor antagonist (anakinra) could inhibit the inflammatory response and improve peak aerobic exercise capacity in patients with recently decompensated systolic HF. METHODS AND RESULTS: We randomly assigned 60 patients with reduced left ventricular ejection fraction (<50%) and elevated C-reactive protein levels (>2 mg/L), within 14 days of hospital discharge, to daily subcutaneous injections with anakinra 100 mg for 2 weeks, 12 weeks, or placebo. Patients underwent measurement of peak oxygen consumption (Vo2 [mL/kg per minute]) and ventilatory efficiency (the VE/Vco2 slope). Treatment with anakinra did not affect peak Vo2 or VE/Vco2 slope at 2 weeks. At 12 weeks, patients continued on anakinra showed an improvement in peak Vo2 from 14.5 (10.5-16.6) mL/kg per minute to 16.1 (13.2-18.6) mL/kg per minute (P=0.009 for within-group changes), whereas no significant changes occurred within the anakinra 2-week or placebo groups. The between-groups differences, however, were not statistically significant. The incidence of death or rehospitalization for HF at 24 weeks was 6%, 31%, and 30%, in the anakinra 12-week, anakinra 2-week, and placebo groups, respectively (log-rank test P=0.10). CONCLUSIONS: No change in peak Vo2 occurred at 2 weeks in patients with recently decompensated systolic HF treated with anakinra, whereas an improvement was seen in those patients in whom anakinra was continued for 12 weeks. Additional larger studies are needed to validate the effects of prolonged anakinra on peak Vo2 and rehospitalization for HF. CLINICAL TRIAL REGISTRATION: URL: http://www.clinicaltrials.gov. Unique identifier: NCT01936909.

Severely Impaired Cardiorespiratory Fitness in Patients With Recently Decompensated Systolic Heart Failure.

Hospital admission for decompensated heart failure marks a critical inflection point in a patient's health. Despite the improvement in signs or symptoms during hospitalization, patients have a high likelihood of readmission, reflecting a lack of resolution of the underlying condition. Surprisingly, no studies have characterized the cardiorespiratory fitness of such patients. Fifty-two patients (38 [73%] male, age 57 [52 to 65] years, left ventricular ejection fraction 31% [24 to 38]) underwent cardiopulmonary exercise testing 4 (1 to 10) days after hospital discharge, when stable and without overt signs of volume overload. Transthoracic Doppler echocardiography, measurement of N-terminal pro-B-natriuretic peptide, and quality of life were also assessed. Aerobic exercise capacity was severely reduced: peak oxygen consumption (pVO2) was 14.1 (11.2 to 16.3) ml/kg/min. Ventilatory inefficiency as indicated by the minute ventilation carbon dioxide production relation (VE/VCO2 slope) >30 and oxygen uptake efficiency slope <2.0 was noted in 41 (77%) and 39 (75%) patients, respectively. Forty-five (87%) patients had 1 of 2 high-risk features (pVO2 < 14 ml/kg/min or VE/VCO2 >30). Perceived functional capacity, measured by the Duke Activity Status Index, was also severely reduced and correlated with pVO2. N-terminal pro-B-natriuretic peptide levels and early transmitral velocity/early mitral annulus velocity (E/e') ratio at echocardiography showed a modest correlation with lower pVO2. In conclusion, patients with recently decompensated systolic heart failure demonstrate severe impairment in cardiorespiratory fitness, severely limiting quality of life.