Bos, J. Martijn

Background: Highly caffeinated energy drinks (HCEDs) can trigger life-threatening cardiac arrhythmias in individuals with and without an underlying genetic predisposition. Though the mechanism(s) responsible for these events remain unclear, it has been postulated that high caffeine may alter heart rate, blood pressure, cardiac contractility, and cardiac repolarization in a manner that is pro-arrhythmic. Objective: To describe our experience regarding sudden cardiac arrest (SCA) events occurring in proximity to HCED consumption in patients with underling genetic heart diseases. Methods: All SCA survivors referred to the Mayo Clinic Windland Smith Rice Genetic Heart Rhythm Clinic for clinical and/or molecular evaluation were reviewed to identify those with a history of HCED consumption prior to their event. Patient demographics, clinical characteristics, documented HCED consumption, and temporal relationship of HCED consumption to SCA were extracted from the electronic medical record. Results: Among 144 SCA survivors with a structurally normal heart, 8 (6 females; mean age at event 28 ± 8 years) experienced an unexplained SCA associated temporally with HCED consumption. Of these, 5 (63%) had either long QT syndrome (n=3) or catecholaminergic polymorphic ventricular tachycardia (n=2). The remaining 3 were diagnosed with unexplained SCA/idiopathic ventricular fibrillation after a comprehensive evaluation. Three patients (37%) were habitual HCED consumers while 5 (63%) imbibed for the first time with consumption ranging from several hours to a few minutes before the SCA. Seven patients (88%) required a rescue shock (average 2 ± 2 shocks/patient) while 1 was manually resuscitated. Upon follow-up, 6 (75%) were dismissed with an implantable cardioverter defibrillator, 1 (13%) on pharmacologic therapy, and 1 (13%) underwent denervation surgery. All SCA survivors have quit drinking HCEDs and have been event-free since. Conclusion: Overall, 8/144 (5.6%) of SCA survivors evaluated in our program experienced a SCA in proximity to consuming a HCED. Although larger cohort studies are needed to elucidate the precise mechanism for HCED-triggered/associated SCA and quantify its precise pro-arrhythmic risk, it seems prudent to sound an early warning.

Background: The estimated prevalence of attention-deficit/hyperactivity disorder (ADHD) globally is about 5%. For patients with catecholaminergic polymorphic ventricular tachycardia (CPVT), ADHD-directed stimulant therapy is relatively contraindicated. However, previous studies have shown that use of these treatments is safe for patients with long QT syndrome, a similar genetic heart disease. Whether this is the same for patients with CPVT remains unknown. Objective: To evaluate ADHD-directed treatment, outcome, and frequency of CPVT-triggered events in patients with CPVT and concomitant ADHD. Methods: A retrospective electronic medical record review of 216 patients with CPVT evaluated in Mayo Clinic’s Windland Smith Rice Genetic Heart Rhythm Clinic was performed to determine the prevalence of concomitant ADHD and the incidence of CPVT-triggered events in these patients. Results: Overall, 14 patients (6%) were diagnosed with CPVT and concomitant ADHD (6 female, average age 19 ± 3 years). At the time of first evaluation, ADHD-directed stimulant therapy was stopped or advised against in 8/14 patients (57%). It was (re)started in 11 patients (79%) following comprehensive evaluation and treatment initiation for CPVT with pharmacologic therapy in 14/14 patients (100%), denervation surgery in 12 (86%), and an implantable cardioverter defibrillator in 4 (29%). Prior to Mayo Clinic evaluation, 10 patients (71%) treated for CPVT had a breakthrough cardiac event, without being on stimulant therapy, while 4 patients (29%) had an event while being treated for both CPVT and ADHD for an average time on stimulant therapy of 6 ± 6 years. Following CPVT treatment optimization and ADHD stimulant (re)initiation, patients have remained event-free for a total of 82 patient years (mean follow-up 6 ± 5 years). Conclusion: Among patients with CPVT, the prevalence of ADHD was similar to that in the general population, which can be treated safely and effectively with stimulant therapy. Although the rate of adverse events was low in stimulant-treated patients, physicians should weigh the potential effects of suboptimal treatment of ADHD with the theoretical proarrhythmic risk from stimulant medications on a case-by-case basis.

Abstract Hypertrophic Cardiomyopathy (HCM) is an inheritable heart disease with the highest rate of sudden cardiac death (SCD) in young adults. Implantable Cardioverter Defibrillator (ICD) therapy is recommended for HCM patients at high risk for SCD. Reviewing the recent clinical literature revealed the potential to improve the selection of candidates for ICD implantation. The current study uses information extracted from echocardiography reports to evaluate HCM patients with ICD and aims to provide a comparative insight into patients who benefited the most from the device therapy, including shock and anti-tachycardia pacing (ATP). The proposed interpretable machine learning approach has used the XGboost algorithm. The model’s performance was considered satisfactory, as evidenced by an accuracy score of 81% and an area under the receiver operating characteristic curve (AUC) value of 69% and SHapley Additive exPlanations (SHAP) identified common properties of HCM patients in each category and provided high-level reasoning and foundation for a clinical decision support tool.

Importance Whether vigorous intensity exercise is associated with an increase in risk of ventricular arrhythmias in individuals with hypertrophic cardiomyopathy (HCM) is unknown. Objective To determine whether engagement in vigorous exercise is associated with increased risk for ventricular arrhythmias and/or mortality in individuals with HCM. The a priori hypothesis was that participants engaging in vigorous activity were not more likely to have an arrhythmic event or die than those who reported nonvigorous activity. Design, Setting, and Participants This was an investigator-initiated, prospective cohort study. Participants were enrolled from May 18, 2015, to April 25, 2019, with completion in February 28, 2022. Participants were categorized according to self-reported levels of physical activity: sedentary, moderate, or vigorous-intensity exercise. This was a multicenter, observational registry with recruitment at 42 high-volume HCM centers in the US and internationally; patients could also self-enroll through the central site. Individuals aged 8 to 60 years diagnosed with HCM or genotype positive without left ventricular hypertrophy (phenotype negative) without conditions precluding exercise were enrolled. Exposures Amount and intensity of physical activity. Main Outcomes and Measures The primary prespecified composite end point included death, resuscitated sudden cardiac arrest, arrhythmic syncope, and appropriate shock from an implantable cardioverter defibrillator. All outcome events were adjudicated by an events committee blinded to the patient’s exercise category. Results Among the 1660 total participants (mean [SD] age, 39 [15] years; 996 male [60%]), 252 (15%) were classified as sedentary, and 709 (43%) participated in moderate exercise. Among the 699 individuals (42%) who participated in vigorous-intensity exercise, 259 (37%) participated competitively. A total of 77 individuals (4.6%) reached the composite end point. These individuals included 44 (4.6%) of those classified as nonvigorous and 33 (4.7%) of those classified as vigorous, with corresponding rates of 15.3 and 15.9 per 1000 person-years, respectively. In multivariate Cox regression analysis of the primary composite end point, individuals engaging in vigorous exercise did not experience a higher rate of events compared with the nonvigorous group with an adjusted hazard ratio of 1.01. The upper 95% 1-sided confidence level was 1.48, which was below the prespecified boundary of 1.5 for noninferiority. Conclusions and Relevance Results of this cohort study suggest that among individuals with HCM or those who are genotype positive/phenotype negative and are treated in experienced centers, those exercising vigorously did not experience a higher rate of death or life-threatening arrhythmias than those exercising moderately or those who were sedentary. These data may inform discussion between the patient and their expert clinician around exercise participation.

Abstract Aims Data on the clinical course of hypertrophic cardiomyopathy (HCM) are mainly derived from tertiary HCM centre studies, and knowledge of clinical outcomes of patients leaving specialty care and returning to local physicians is limited due to gaps between clinical encounters or complete loss of follow-up. This survey aims to describe the clinical course of HCM in patients following their evaluation at a tertiary referral centre. Methods and results A comprehensive outcomes survey was developed and sent to 4495 eligible patients with HCM previously evaluated at Mayo Clinic. Questions assessed general well-being, New York Heart Association class, procedures performed, and probable HCM-triggered ventricular arrhythmic events (VAEs) since last visit. In total, 2058 patients (mean age 63 ± 15 years; 42% female) responded to the survey covering a total of 10 510 patient-years with an average of 5.4 ± 6.4 years of follow-up since their last on-campus/virtual visit to Mayo Clinic. During their time away from specialty care, 20% of patients reported having cardiac-related hospitalizations and 25% reported having cardiac-related procedures. Similar to high-risk referral cohorts, 5% of patients reported VAEs with an event rate of 0.98 events/100 patient-years. The prevalence of atrial fibrillation, syncope, pre-syncope, cardiac-related hospitalizations, and VAEs during time away from specialty care increased significantly with increasing New York Heart Association class (P < 0.001). Conclusions Acknowledging ascertainment bias, the clinical course of patients away from tertiary care may be more severe than previously anticipated. Among those with exertional symptoms, HCM-related morbidity increased substantially. Higher risk HCM patients should remain in contact with HCM specialty care.

Background: Hypertrophic cardiomyopathy (HCM) is characterized by asymmetric left ventricular hypertrophy. Currently, hypertrophy pathways responsible for HCM have not been fully elucidated. Their identification could serve as a nidus for the generation of novel therapeutics aimed at halting disease development or progression. Herein, we performed a comprehensive multi-omic characterization of hypertrophy pathways in HCM. Methods: Flash-frozen cardiac tissues were collected from genotyped HCM patients (n=97) undergoing surgical myectomy and tissue from 23 controls. RNA sequencing and mass spectrometry–enabled deep proteome and phosphoproteomic assessment were performed. Rigorous differential expression, gene set enrichment, and pathway analyses were performed to characterize HCM-mediated alterations with emphasis on hypertrophy pathways. Results: We identified transcriptional dysregulation with 1246 (8%) differentially expressed genes and elucidated downregulation of 10 hypertrophy pathways. Deep proteomic analysis identified 411 proteins (9%) that differed between HCM and controls with strong dysregulation of metabolic pathways. Seven hypertrophy pathways were upregulated with antagonistic upregulation of 5 of 10 hypertrophy pathways shown to be downregulated in the transcriptome. Most upregulated hypertrophy pathways encompassed the rat sarcoma-mitogen-activated protein kinase signaling cascade. Phosphoproteomic analysis demonstrated hyperphosphorylation of the rat sarcoma-mitogen-activated protein kinase system suggesting activation of this signaling cascade. There was a common transcriptomic and proteomic profile regardless of genotype. Conclusions: At time of surgical myectomy, the ventricular proteome, independent of genotype, reveals widespread upregulation and activation of hypertrophy pathways, mainly involving the rat sarcoma-mitogen-activated protein kinase signaling cascade. In addition, there is a counterregulatory transcriptional downregulation of the same pathways. Rat sarcoma-mitogen-activated protein kinase activation may serve a crucial role in hypertrophy observed in HCM.

Abstract Aims In catecholaminergic polymorphic ventricular tachycardia (CPVT), the exercise-stress test (EST) is the cornerstone for the diagnosis, risk stratification, and assessment of therapeutic efficacy, but its repeatability is unknown. We aimed to test the repeatability of ventricular arrhythmia characteristics on the EST in patients with CPVT. Methods and results EST-pairs (ESTs performed within 18 months between 2005 and 2021, on the same protocol, and without or on the exact same treatment) of patients with RYR2-mediated CPVT from two specialized centres were included. The primary endpoint was the repeatability of the maximum ventricular arrhythmia score [VAS: 0 for the absence of premature ventricular contractions (PVCs); 1 for isolated PVCs; 2 for bigeminal PVCs; 3 for couplets; and 4 for non-sustained ventricular tachycardia]. Secondary outcomes were the repeatability of the heart rate at the first PVC and the ΔVAS (the absolute difference in VAS between the EST-pairs). A total of 104 patients with 349 EST-pairs were included. The median duration between ESTs was 343 (interquartile range, 189–378) days. Sixty (17.2%) EST-pairs were off therapy. The repeatability of the VAS was moderate {Krippendorf α, 0.56 [95% confidence interval (CI), 0.48–0.64]}, and the repeatability of the heart rate at the first PVC was substantial [intra-class correlation coefficient, 0.78 (95% CI, 0.71–0.84)]. The use of medication was associated with a higher odds for a ΔVAS > 1 (odds ratio = 3.52; 95% CI, 2.46–4.57; P = 0.020). Conclusion The repeatability of ventricular arrhythmia characteristics was moderate to substantial. This underlines the need for multiple ESTs in CPVT patients and CPVT suspicious patients and it provides the framework for assessing the therapeutic efficacy of novel CPVT therapies.

Background: The study of hypertrophic cardiomyopathy (HCM) can yield insight into the mechanisms underlying the complex trait of cardiac hypertrophy. To date, most genetic variants associated with HCM have been found in sarcomeric genes. Here, we describe a novel HCM-associated variant in the noncanonical Wnt signaling interactor WTIP (Wilms tumor interacting protein) and provide evidence of a role for WTIP in complex disease. Methods: In a family affected by HCM, we used exome sequencing and identity-by-descent analysis to identify a novel variant in WTIP (p.Y233F). We knocked down WTIP in isolated neonatal rat ventricular myocytes with lentivirally delivered short hairpin ribonucleic acids and in Danio rerio via morpholino injection. We performed weighted gene coexpression network analysis for WTIP in human cardiac tissue, as well as association analysis for WTIP variation and left ventricular hypertrophy. Finally, we generated induced pluripotent stem cell–derived cardiomyocytes from patient tissue, characterized size and calcium cycling, and determined the effect of verapamil treatment on calcium dynamics. Results: WTIP knockdown caused hypertrophy in neonatal rat ventricular myocytes and increased cardiac hypertrophy, peak calcium, and resting calcium in D rerio . Network analysis of human cardiac tissue indicated WTIP as a central coordinator of prohypertrophic networks, while common variation at the WTIP locus was associated with human left ventricular hypertrophy. Patient-derived WTIP p.Y233F-induced pluripotent stem cell–derived cardiomyocytes recapitulated cellular hypertrophy and increased resting calcium, which was ameliorated by verapamil. Conclusions: We demonstrate that a novel genetic variant found in a family with HCM disrupts binding to a known Wnt signaling protein, misregulating cardiomyocyte calcium dynamics. Further, in orthogonal model systems, we show that expression of the gene WTIP is important in complex cardiac hypertrophy phenotypes. These findings, derived from the observation of a rare Mendelian disease variant, uncover a novel disease mechanism with implications across diverse forms of cardiac hypertrophy.

The analysis and interpretation of cardiac magnetic resonance (CMR) images are often time-consuming. The automated segmentation of cardiac structures can reduce the time required for image analysis. Spatial similarities between different CMR image types were leveraged to jointly segment multiple sequences using a segmentation model termed a multi-image type UNet (MI-UNet). This model was developed from 72 exams (46% female, mean age 63 ± 11 years) performed on patients with hypertrophic cardiomyopathy. The MI-UNet for steady-state free precession (SSFP) images achieved a superior Dice similarity coefficient (DSC) of 0.92 ± 0.06 compared to 0.87 ± 0.08 for a single-image type UNet (p < 0.001). The MI-UNet for late gadolinium enhancement (LGE) images also had a superior DSC of 0.86 ± 0.11 compared to 0.78 ± 0.11 for a single-image type UNet (p = 0.001). The difference across image types was most evident for the left ventricular myocardium in SSFP images and for both the left ventricular cavity and the left ventricular myocardium in LGE images. For the right ventricle, there were no differences in DCS when comparing the MI-UNet with single-image type UNets. The joint segmentation of multiple image types increases segmentation accuracy for CMR images of the left ventricle compared to single-image models. In clinical practice, the MI-UNet model may expedite the analysis and interpretation of CMR images of multiple types.