Vizentin, Vanessa Karlinski

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.

Introduction: Long QT syndrome (LQTS) is a potentially life-threatening genetic heart disease. Patients with LQTS may also have co-existent mental health illnesses that may benefit from psychiatric medications. However, because many of these medications have QT-prolonging potential (www.crediblemeds.org), many of these patients receive suboptimal mental health care. Objective: To evaluate the frequency, management, and incidence of breakthrough cardiac events (BCEs) in patients with LQTS and concomitant mental health issues treated with psychiatric medications. Methods: A retrospective review was conducted on patients cared for in Mayo Clinic's Windland Smith Rice Genetic Heart Rhythm Clinic between 2000 and 2024 focusing on patients with LQTS and a concomitant psychiatric diagnosis requiring medication with known, possible or conditional risk of torsades de pointes (TdP). Electronic medical records were reviewed for data. BCEs were defined as LQTS-triggered syncope, seizures, appropriate ICD therapy, sudden cardiac arrest (SCA), or sudden cardiac death (SCD). Patients with missing information were excluded. Results: Overall, 195 /1899 LQTS patients [10%, 86 (43%) with LQT1, 83 (42%) with LQT2, and 16 (8%) with LQT3] had a concomitant psychiatric diagnosis requiring medication [150 female (76%), mean age at diagnosis 27 ± 18 years, median follow-up time 6.6 years (IQR 2.9-13)]. The most common psychiatric conditions were depression (71%), anxiety (62%), and ADHD (9%). The mean duration of therapy was 3.36 +/- 3.48 years and the most common medications used were fluoxetine (26%), sertraline (14%), and escitalopram (11%). There was no significant difference in QTc after starting the first psychiatric medication when compared to baseline (473 ± 33 vs 474 ± 35 ms, p=0.6). Prior to their LQTS diagnosis and while therefore untreated, 61/195 (31%) had at least 1 LQTS-associated cardiac event. This occurred in the setting of a psychiatric drug in 7 patients (11%). Following LQTS diagnosis and treatment, 14/195 patients (7%) have experienced a non-lethal BCE of which only 3/14 (21%) while on psychiatric medications. Conclusions: Although avoidance of medications with known QT-prolonging potential is prudent, attention to patient’s overall well-being besides just their LQTS must be given. After correct diagnosis and treatment, LQTS patients with concomitant mental health issues may be safely and effectively treated with medications known to prolong QTc.

Abstract Introduction Hypertrophic cardiomyopathy (HCM) is the most prevalent heritable cardiomyopathy typically transmitted in an autosomal dominant fashion. There is growing importance in identifying genetic test positive patients given its prognostic value. The Mayo HCM Genotype Predictor Score has been extensively validated for assessment of patient’s pre-test probability for genotype positive HCM and helps guide clinical decision-making based on clinical and echocardiographic variables. Herein, we evaluated the role of cardiac magnetic resonance (CMR) to enhance the genotype predictor score. Purpose Evaluate performance of the Mayo Clinic HCM Genotype Predictor Score using CMR variables, and develop an updated, CMR incorporated score. Methods Retrospective analysis was conducted on 175 unrelated HCM patients with at least 1 MRI and a HCM genetic testing seen at the Mayo Clinic between April 2004 and April 2018. Phenotyping information was obtained through review of electronic medical records. The original Mayo HCM Genotype Predictor Score was calculated using both echocardiography and clinical variables. An updated score was created incorporating CMR-specific variables. Diagnostic accuracy of the models was assessed thought Receiver Operating Characteristic (ROC) curves. Results Overall, 108 (62%) were males with a mean age at CMR of 51 ± 18 years. The yield of positive genetic test for the echocardiogram-derived Mayo HCM Genotype Predictor Score ranged from 38% for patients with -1 point to 100% for patients with 4 or 5 points. There was a significant incremental increase in diagnostic yield between score subgroups (p < 0.01) with an AUC of 0.659 (Figure 1A). Similar findings were observed using CMR variables (AUC of 0.697; Figure 1B). Univariate and multivariate analysis identified late gadolinium enhancement (LGE) as a strong predictor of a positive genetic test (OR 3.72; p=0.002), and it was added to the original score to create a new version. The Updated Mayo HCM Genotype Predictor Score predicted a positive genetic test ranging from 25% for patients with -1 point to 100% for patients with 5 or 6 points (p < 0.01). There was a significant increase in diagnostic accuracy when compared to the original score (AUC 0.724 vs 0.679; p=0.03; Figure 1C). Conclusion Using LGE, the updated CMR-based Mayo HCM Genotype Predictor score provides a simple and improved tool to aid in genetic counseling for HCM patients.