Giudicessi, John R.

Background: Hypertrophic cardiomyopathy (HCM) is a genetic cardiomyopathy marked by increased left ventricular wall thickness, leading in some cases to left ventricular outflow tract (LVOT) obstruction, heart failure, and arrhythmias. Mavacamten, a selective allosteric inhibitor of cardiac myosin, has demonstrated benefits in improving hemodynamics and reducing LVOT obstruction. However, its impact on arrhythmic burden remains unclear, with reports of early atrial fibrillation (AF) risk contrasting with long-term reductions in arrhythmias. This study assesses the temporal patterns of Holter-detected arrhythmias in HCM patients treated with mavacamten. Methods: This retrospective study included HCM patients from three Mayo Clinic sites. Baseline demographic, clinical, and echocardiographic data were collected. Holter monitoring was performed at baseline, short-term (<6 months), and long-term (>6 months) follow-up. Arrhythmic events, including premature atrial contractions (PACs), premature ventricular contractions (PVCs), and supraventricular tachycardia (SVT), were analyzed using standardized rates per 24 h. Statistical comparisons utilized the Wilcoxon signed-rank test. Results: Twenty-seven patients (56% female, median age 66 years) were included. PACs, PVCs, and SVT duration transiently but not significantly increased at short-term follow-up but returned to baseline at long-term follow-up. No sustained or high-risk ventricular arrhythmias were observed. Conclusions: Mavacamten is associated with transient arrhythmic fluctuations early in treatment, followed by stabilization. These findings support its long-term electrophysiological safety and underscore the need for early rhythm monitoring. Further research should explore its role in arrhythmic risk stratification in HCM patients.

ABSTRACT Background Mitral annular disjunction (MAD) carries an increased risk of complex ventricular arrhythmias, which can lead to sudden cardiac death. Many of these patients undergo implantable cardioverter defibrillator (ICD) implantation, but their ICD outcomes are not known. Objective The aim of this study was to assess the outcomes of ICD implantation and the predictors of appropriate ICD therapies in patients with MAD. Methods The study included patients with MAD who underwent ICD implantation. Clinical, electrocardiographic, cardiac imaging, and device therapy data were collected. Results Forty‐nine patients with MAD and ICD were included. Median age was 49 (21) years, and 29 (59%) were female. 13 (27%) patients underwent ICD implantation for primary prevention and 36 (73%) patients for secondary prevention. Over a median follow‐up of 27.3 (35.3) months, 23 (47%) patients received ICD therapies. 18 (37%) patients had appropriate ICD therapies, and 5 (10%) patients had inappropriate ICD shocks. Median time to first appropriate therapy was 22.3 (63.3) months. In patients with a secondary prevention ICD indication, the rate of appropriate ICD therapies was 44%, while in patients with a primary prevention ICD indication, it was 15%. Among patients with appropriate ICD therapies, the first therapies were delivered for monomorphic ventricular tachycardia (VT) in 7 (39%) patients and polymorphic VT or ventricular fibrillation (VF) in 11 (61%) patients. Patients with appropriate ICD therapies were more likely to have a history of SCA ( p = 0.003) and/or low left ventricular ejection fraction (LVEF) ( p = 0.022) before ICD implantation as compared to patients without appropriate ICD therapies. Conclusions In our cohort of patients with MAD and ICD, appropriate ICD therapies were common. Most appropriate ICD therapies were delivered for polymorphic VT or VF. Larger studies are needed to elucidate the mechanisms of VAs and refine risk stratification in MAD.

BACKGROUND: Patients with arrhythmogenic mitral valve prolapse syndrome are at increased risk for life-threatening ventricular arrhythmias, but studies have been limited by small sample sizes. We sought to assemble an international arrhythmogenic mitral valve prolapse syndrome registry to delineate the clinical, imaging, and treatment characteristics of patients with arrhythmogenic mitral valve prolapse syndrome who survived sudden cardiac arrest (SCA) or had sustained ventricular tachycardia (VT) or ventricular fibrillation. METHODS: In this descriptive registry, we characterized patients with arrhythmogenic mitral valve prolapse syndrome who survived SCA, sustained VT, or ventricular fibrillation. Deidentified data were abstracted locally and combined centrally. RESULTS: We included 148 patients who had SCA or VT/ventricular fibrillation. Patients had a mean age of 43.7±15.4 years; 68% were women, 73% had bileaflet prolapse, 65% had mitral annular disjunction, 67% had nonsustained VT, and 59% had inferolateral T-wave inversions. Syncope (n=54, 48%) and anterolateral T-wave inversion (n=26, 22%) were relatively common. Catheter ablation was performed in 50 (35%) patients for premature ventricular complexes and in 18 (17.7%) patients for VT. Sites of origin for arrhythmias were commonly in the papillary muscles, fascicles, mitral annulus, and inferior/inferolateral left ventricle. CONCLUSIONS: In this international descriptive registry of patients with arrhythmogenic mitral valve prolapse syndrome and SCA, patients were young, women, and had bileaflet mitral valve prolapse, mitral annular disjunction, inferolateral T-wave inversions, and nonsustained VT. A history of syncope and anterolateral T-wave inversions was relatively common in patients who survived SCA or sustained VT/ventricular fibrillation.

Background A multidisciplinary approach improves guideline‐directed medical therapy in systolic heart failure (HF), but its efficacy in patients with HF due to cardiac sarcoidosis is unreported. Methods and Results In a retrospective cohort study, we reviewed 848 patients from our institutional cardiac sarcoidosis clinics, identifying those with a cardiac sarcoidosis diagnosis, HF (left ventricular ejection fraction <50%) at index evaluation, and echocardiograms within 90 days and 11 to 36 months. Patients were stratified by participation in a pharmacist‐led medication therapy management (MTM) program for guideline‐directed medical therapy optimization (MTM versus non‐MTM [NMTM]) without randomization. Demographics, left ventricular ejection fraction, guideline‐directed medical therapy (quantified by Kansas City Medical Optimization score), and immunosuppressive therapy were assessed. Primary outcomes included changes in Kansas City Medical Optimization score, left ventricular ejection fraction, and cardiovascular event–free survival (unplanned HF hospitalization, left ventricular assist device /heart transplant, or death). The final cohort included 111 patients (median age, 57 years; 34% women; 64% New York Heart Association class I–II); 43 (39%) were MTM and 68 (61%) were NMTM. Mean Kansas City Medical Optimization score was similar at index evaluation (MTM, 23.2; NMTM, 29.6; P =0.83). At follow‐up (median, 16 months), the Kansas City Medical Optimization score increased significantly in both groups (MTM, 23.2 to 74.8; P <0.001; NMTM, 29.6 to 58.7; P <0.001) but was higher in MTM ( P =0.001). Mean left ventricular ejection fraction trended toward higher values in MTM (44.4% versus 40.0%, P =0.05). The primary clinical outcome occurred in 1 MTM (2.3%) and 16 NMTM (23.5%) patients, with higher risk in NMTM (hazard ratio, 11.97 [95% CI, 1.58–90.54]; P =0.002). Conclusions In this retrospective cohort study, a pharmacist‐led MTM program was associated with favorable guideline‐directed medical therapy optimization and lower risk of adverse cardiovascular outcomes in patients with cardiac sarcoidosis with HF.

Background: Current guidelines discourage athletes with a positive genetic test for arrhythmogenic cardiomyopathy (ACM) from participating in sports. The evidence that exercise may act as a disease-accelerator is most compelling for PKP2-mediated ACM. As such, shared decision making (SDM) and return-to-play (RTP) for athletes with ACM may be possible for some genotypes. Objective: To examine the management, RTP, outcomes, and evolution of phenotype among athletes with genotype positive ACM. Methods: A retrospective review of the electronic medical records was performed on all self-identified athletes with genotype positive ACM. They were evaluated, risk stratified, and treated in Mayo Clinic’s (MC) Windland Smith Rice Genetic Heart Rhythm Clinic. Results: Among the 621 patients with genotype-positive ACM, there were 38 athletes [16 females (42%); mean age at either clinical diagnosis or positive genetic test 28 ± 19 years; mean follow-up 4 ± 4 years] participating in sports at all levels. The majority, 21 (55%), had PKP2-ACM and 7 (18%) had DSP-ACM. Prior to their first MC evaluation, 15 athletes (39%) were engaged in long distance running, swimming, cycling, or triathlons. Seven athletes (18%) had a non-lethal breakthrough cardiac event (BCE) after diagnosis, but prior to MC evaluation. During 150+ athlete-years of follow-up, there have been no ACM-associated deaths, but 5 athletes (13%) experienced a non-lethal BCE. Twenty-two athletes (58%) were phenotype negative at time of first MC evaluation including 10 endurance athletes (45%). Of these, 3 (14%) converted to phenotype positive (average age at conversion 25 ± 15 years), while 7/16 (44%) phenotype positive athletes exhibited further disease progression (average age at progression 32 ± 18 years). For these 10 athletes who either converted or progressed, treatment intensification included an ablation in 4, ICD in 2, and a heart transplant in 2. Seven resumed athletic activity in some capacity after conversion/progression and a non-lethal BCE occurred in 3. Conclusions: This is the first single center cohort of patients with ACM being empowered to remain an athlete. In contrast to athletes with other genetic heart diseases (GHDs), these athletes have exhibited more cardiac events, although nonfatal, and higher rates of disease conversion/progression than our other GHDs. Further studies are needed to determine how to effectively and safely enable appropriate sports participation in genetically-mediated ACM

Introduction: Anthracyclines (AC), a class of chemotherapeutic drugs, are used to treat various cancers, including breast cancer (BC). However, AC cause dose-dependent cardiac toxicity. Practice guidelines list pre-existing cardiomyopathy as a risk factor for cancer therapy-related cardiac dysfunction (CTRCD), but there is a lack of data on cardiotoxicity risk in patients with left ventricular (LV) hypertrabeculation without LV hypertrophy/dilation. We present a patient with LV hypertrabeculation who developed LV dysfunction after AC chemotherapy for BC. Description of Case: A 55-year-old woman diagnosed with multicentric invasive ductal carcinoma (IDC) of the right breast, stage IIA (cT3 cN1 cM0), grade 2, ER+/PR+/HER2-, was treated with neoadjuvant Paclitaxel for 3 months. Before AC-based chemotherapy, stress cardiac MRI due to residual post-COVID-19 dyspnea showed LV hypertrabeculation with a non-compacted/compacted ratio of 2.3, LVEF 56%, and no delayed enhancement. Transthoracic echocardiography (TTE) reported an LVEF of 52% with GLS of -17%. The patient's electrocardiogram (ECG) showed normal sinus rhythm, and NT-pro BNP levels were <20 pg/mL. Genetic testing identified a rare variant in MYH7-encoded myosin heavy chain 7 (p.Arg941Leu-MYH7). She had no cardiovascular (CV) risk factors or family history of CV disease. She then underwent 4 cycles of Doxorubicin (cumulative dose 232.2 mg/m2) and Cyclophosphamide, followed by bilateral mastectomy and adjuvant radiotherapy (5000 cGy in 25 fractions). One year after chemotherapy, follow-up TTE showed LVEF decreased to 45% with GLS of -17%. The patient’s ECG remained normal, and NT-pro BNP levels were <36 pg/mL. Despite an LVEF decline, not all criteria for CTRCD were met, suggesting a gene-environment interplay between her chemotherapy and pre-existing MYH7-mediated non-dilated LV cardiomyopathy (NDLVC) with hypertrabeculation. The patient has remained without symptoms of heart failure and is currently taking Letrozole 2.5 mg daily. Discussion: This case offers a unique perspective on a BC patient treated with AC chemotherapy, who has a possible MYH7-mediated NDLVC with hypertrabeculation, and who experienced an LVEF decline of indeterminate significance. While the association of her possible NDLVC with hypertrabeculation is uncertain, the safety of AC in patients with isolated hypertrabeculation or NDLVC with hypertrabeculation, as introduced by the 2023 ESC cardiomyopathy guidelines, remains to be defined.

Background: LQTS is a genetic heart disease associated with an increased risk of sudden death. Despite advances in genetic testing, a small subset of patients still lacks identifiable genetic markers. Consequently, the true prevalence and clinical phenotype of genotype negative remains to be determined. Objective: To determine the prevalence and clinical characteristics of patients with a clinical diagnosis of LQTS but a negative genetic test. Methods: A retrospective review was conducted on patients evaluated and treated at a tertiary hospital between 2000 and 2024, focusing on those with a clinical diagnosis of LQTS, but a negative genetic test for all LQTS-associated genes, with available follow-up of at least 1 year. Results: After exclusion for follow-up and lack of genetic testing, the study cohort consisted of 1834 patients with LQTS including 1708 (93%) with a (likely) pathogenic (LP/P), LQTS-causative variant. Also, in 95 patients (5%), their variant of uncertain significance was clinically upgraded to a LP/P-variant, leaving only 31 patients classified as phenotype positive but genotype negative (1.6%). Of these, 16/31 underwent next-generation genetic sequencing, revealing the genetic cause in 6/16 cases (37%; 0.3% of all patients). For the remaining 25 genotype negative LQTS patients (1.3%), the mean age at diagnosis was 26 ± 15 years, with 19 (76%) being female, and an average initial QTc of 497 ± 41 ms. In total, 11 patients (44%) experienced a cardiac event before diagnosis [1 sudden cardiac arrest (SCA), 1 Torsades, 1 VT, 8 syncopes] and 1 patient had his first cardiac event during follow-up; 7/12 patients had more than one subsequent event. Twenty patients were proband (80%) and 6 had a family history of SCA. Eleven patients received an ICD (44%), left cardiac sympathetic denervation was performed in 4 (16%), and 2 patients experienced arrhythmia-related deaths (8%). The mean follow-up since diagnosis was 7 ± 5 years. Conclusion: With a prevalence of genotype-negative LQTS of 2%, the number of these patients is much lower than previously suggested, underscoring the advancements in identifying new genetic markers and the role of phenotype-enhanced variant adjudication and next-generation sequencing. Additionally, significant disease severity was observed in the remaining patients, emphasizing the pivotal role of genotype-phenotype correlations and risk stratification in managing and counseling patients lacking identified LQTS-causing mutations.

Background: Arrhythmogenic cardiomyopathy (ACM) is a genetic heart disease characterized by proclivity for ventricular arrhythmias and systolic dysfunction. Rarely, sudden cardiac arrest (SCA) is the presenting event in ACM. These individuals may have concealed disease with no appreciable structural manifestations on imaging. Aims: To determine the prevalence, clinical features, and outcomes of patients with genotype-positive ACM who presented with a sentinel SCA. Methods: In this retrospective study, 445 genotype-positive ACM patients evaluated from 1/2015-4/2024 were analyzed to identify those whose initial presentation was SCA. Pertinent demographic, clinical, genetic, and outcome data were extracted from the electronic medical record. Structural manifestations were defined by having one of the following on baseline TTE: EF < 50%, LVEDV >56 mL (male) or >51 mL (female), or regional RV akinesia, dyskinesia, or aneurysm. Categorical variables are presented as number (%), and continuous variables as median (IQR). Statistical analysis was done using Fisher’s exact test (categorical), t-test (continuous), and Logrank test (survival). Patients were censored at time of transplant, death, or last followup. Results: Overall, 14/445 (3%) ACM patients presented with sentinel SCA [71% male; median age at SCA 39 (IQR 30-46)]. The most common genetic substrates were DSP -encoded desmoplakin (n=4; 29%), LMNA -encoded lamin A/C (n=3; 21%), and PKP2 -encoded plakophilin-2 (n=3; 21%). During a median followup of 8.4 years, 12 (86%) experienced appropriate ICD shocks, 8 (57%) required catheter ablation for ventricular arrhythmias, 6 (42%) underwent transplant, and 2 (14%) died of cardiac causes. Notably, 5 (35%) patients did not have evidence of structural disease during baseline evaluation. Compared to those with structural disease, this group was younger [median age 28 (IQR 21-29) vs 45 (IQR 41-48), p = 0.002] and less likely to undergo transplant [0 (0%) vs 6 (42%), p = 0.03]. Conclusions: Sentinel SCA is a rare presentation in ACM and may precede overt structural cardiac changes in a subset of younger patients. This population remains at increased risk for recurrent ventricular arrhythmias and often require advanced therapies.

Background: Although exercise stress testing (EST) has shown to unmask latent electrical substrates in PKP2 -mediated arrhythmogenic cardiomyopathy (ACM), the prognostic role of EST-induced ventricular arrhythmia (VA) patterns in PKP2-ACM patients is unclear. Objective: To examine the exercise-induced VA patterns observed during EST in PKP2-ACM patients and explore their correlation with major VA outcomes. Methods: We retrospectively analyzed 621 patients with either genotype-positive ACM or genotype-positive dilated cardiomyopathy evaluated between 01/2015 and 04/2024 to identify those with a disease-causative variant in PKP2 (N = 108). After exclusion of 38 PKP2-ACM patients without EST data, demographic and electrocardiographic data was extracted from the electronic medical record. The arrhythmic burden [premature ventricular contractions (PVCs), PVCs in bigeminy, PVC couplets, non-sustained VT (NSVT), sustained VT, ventricular fibrillation (VF), and PVCs/minute] during each EST phase (baseline, peak, active and passive recovery) were reviewed and correlated with major VA outcomes [sudden cardiac arrest (SCA), sustained VT, and appropriate implantable cardioverter-defibrillator (ICD) shocks]. Results: A total of 186 exercise tests from 70/108 (65%) PKP2-ACM patients (mean age 36 ± 20 years, 40 % male) were analyzed. The presence and burden of PVCs occurring singly, bigeminy, couplets. and NSVT were more prevalent during the recovery phase, specifically the passive recovery phase ( Table ). PKP2-ACM patients with structural disease (64%) were more likely to have an increased VA burden during recovery than those without structural disease [28/45 (62%) vs 4/25 (16%); p<0.001]. Interestingly, the presence of an increased arrhythmic burden (worsening PVCs/min or complex PVCs) during the recovery was associated with major VA over a median follow-up of 47 months (HR 8.576 [1.015-72.449]; p= 0.019). Conclusion: Increased arrhythmic burden during the recovery phase (late > early) is associated with an increased risk of major VAs in PKP2-ACM. Further studies are needed to understand if this observation extends to other ACM genotypes and whether EST-induced VA patterns can be used to assess therapeutic efficacy in PKP2-ACM.

Background: We identified a novel, ultra-rare missense variant (p.R534S) in DENND3 as a potential disease-susceptibility variant in a multi-generational pedigree of familial idiopathic ventricular fibrillation (IVF). DENND3 is a guanine nucleotide exchange factor and activator for small GTPase Rab proteins involved in endosome and ion channel membrane trafficking. However, the role of DENND3 in the heart and its potential involvement in cardiac arrhythmias are unknown. Objective: To functionally characterize DENND3-p.R534S and determine its impact on channel trafficking. Methods: Heterologous co-expression studies in TSA201 cells were performed with DENND3-WT or DENND3-p.R534S and ion channels: KCNQ1 (Kv7.1, IKs), KCNH2 (Kv11.1, IKr), SCN5A (Nav1.5, INa), or CACNA1C (Cav1.2, ICa) as well as Rab proteins (Rab4, Rab5, Rab6, Rab7, Rab11, Rab12). Patient-specific DENND3-p.R534S iPSC-derived cardiomyocytes (iPSC-CMs) and isogenic controls (IC) were created. Localization and expression of ion channel and Rab proteins was assessed using immunofluorescence (IF) by super resolution AiryScan microscopy. GTPase-Glo assays measured Rab protein activity. Electrophysiology studies using patch-clamp and FluoVolt were performed on iPSC-CM models. Results: IF imaging showed significant increases in membrane expression of KCNQ1 (11714±157to 21929±378, p<0.05), KCNH2 (11378±160 to 31965±544, p<0.05), , SCN5A (10339±8 to 11225±23, p<0.05), and CACNA1C (11879±83 to 13749±138, p<0.05) in DENND3-p.R534S compared to DENND3-WT expressing TSA201 cells. Rab5 distribution was altered significantly by the DENND3-p.R534S variant, with increased dispersion away from the nucleus (0.23±0.01 vs. 0.17±0.01, p<0.05) and increased proximity to the plasma membrane (0.16±0.02 vs. 0.23±0.01, p<0.05). Additionally, Rab5 activity was enhanced significantly (57% increase) by p.R534S versus WT (p<0.05). iPSC-CMs revealed similar increases in channel membrane accumulation and irregular arrhythmic activity including frequent action potential duration alternans and afterdepolarizations in 78% of p.R534S iPSC-CMs versus none in IC cells (p<0.05). Conclusion: DENND3 is a novel ion channel trafficking protein in the heart. The DENND3-p.R534S variant disrupts cardiac ion channel trafficking. These findings highlight DENND3’s role in cardiac ion channel distribution, cellular function, and potential association with arrhythmogenic risk.