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A review of the literature concerning the causation of prolonged Q-T interval syndrome is presented. A fatal case, 50 years of age, with this rare entity is also reported, in whom a sudden cardiac arrest occurred 46 min after induction of anaesthesia. An outline for the successful anaesthetic management of patients with prolonged Q-T interval syndrome is suggested.
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BACKGROUND: Congenital long QT syndrome (LQTS) is a cardiac channelopathy with increased risk of cardiac-triggered syncope/seizures, sudden cardiac arrest, and sudden cardiac death. OBJECTIVE: This study aimed to describe the transcriptomic and proteomic profiles in patient-derived inducible pluripotent stem cell-derived cardiomyocyte (iPSC-CM) models of the 3 canonical genotypes of congenital LQTS: LQT1, LQT2, and LQT3 and integrate these omics-level findings with each other and with population/clinical level QT-genome-wide association study (GWAS) data. METHODS: LQT1, LQT2, LQT3 and respective isogenic control iPSC-CMs were cultured, and RNA and protein samples were collected. RNA sequencing and mass spectrometry-enabled proteomic analysis was performed. PrediXcan analysis was performed using QT GWAS summary statistics and transcriptome expression data. Differential gene and protein expression and ingenuity pathway analysis (IPA) was performed comparing each LQT genotype with its respective isogenic control. RESULTS: 1645 differentially expressed genes (DEGs) were identified; 13 were altered in all 3 LQTS genotypes. IPA analysis of DEGs revealed 301 altered pathways; 47 were altered in all LQTS genotypes. Proteomic analysis identified 2561 differentially expressed proteins (DEPs); 30 were altered in all 3 genotypes. IPA analysis of DEPs identified 646 altered pathways. 306 genes/proteins were identified as significantly altered in both the transcriptome and proteome; pathway analysis of these 301 genes identified 201 altered pathways. 7 pathways were altered in all 3 LQTS genotypes in both the transcriptome and proteome. Integration of the population-level PrediXcan results and the cardiomyocyte-derived omics results identified multiple shared pathways. CONCLUSION: Multi-omics analysis of LQTS and integration of omics results with QT GWAS data reveals that primary LQTS-causative ion channel defects precipitate secondary alterations in a wide range of cellular pathways. Our findings suggest more broad molecular level changes throughout the cell. This study lays the foundation for further exploration of broad cellular changes resulting from ion channel disturbances and how they contribute to disease mechanism.
BACKGROUND AND AIMS: Patients with catecholaminergic polymorphic ventricular tachycardia (CPVT) are at risk for potentially life-threatening arrhythmic events (AEs) even while treated with β-blockers. The aim was to develop a model for individualized prediction of AEs in patients with RYR2-mediated CPVT on β-blocker monotherapy. METHODS: The derivation and independent validation cohorts included 743 and 129 patients, respectively. AEs were defined as arrhythmic syncope, appropriate implantable cardioverter-defibrillator shock, sudden cardiac arrest (SCA), and sudden cardiac death. Near-fatal or fatal AEs (nf/fAEs) included all AEs except for arrhythmic syncope. Prediction models using Cox regression were developed and internally and externally validated. RESULTS: A total of 102 (13.7%) patients in the derivation cohort and 24 (18.6%) patients in the validation cohort experienced ≥1 AE over a median follow-up of 5.1 [interquartile range (IQR), 7.7] and 2.4 (IQR, 4.4) years, respectively. Predictors of AE were arrhythmic syncope or SCA prior to diagnosis and age at β-blocker initiation. In the derivation and validation cohorts, the optimism-corrected C-indices of the models for AE were 0.67 [95% confidence interval (CI) 0.62-0.72] and 0.59 (95% CI 0.48-0.71), respectively. For nf/fAEs, ventricular arrhythmia severity before β-blocker initiation was a fourth independent predictor, and C-indices of the models in the derivation and validation cohorts were 0.74 (95% CI 0.68-0.80) and 0.60 (95% CI 0.47-0.72), respectively. In the derivation cohort, calibration slopes were 1.00 (95% CI 0.59-1.41) for AE and 1.00 (95% CI 0.69-1.32) for nf/fAE. CONCLUSIONS: These externally validated risk prediction models using clinical parameters accurately distinguished CPVT patients on β-blocker monotherapy at low and high risk for future AEs while treated with β-blockers. These models provide guidance for implementation of clinical management therapies to prevent AEs in patients with CPVT.
BACKGROUND: Sodium glucose co-transporter 2 inhibitors (SGLT2i) may exert antiarrhythmic effects, but their association with ventricular arrhythmias remains unclear. OBJECTIVE: We conducted a systematic review to evaluate the association between SGLT2i use and the risk of ventricular arrhythmias, cardiac arrest, and sudden cardiac death compared with other antidiabetic medications or no SGLT2i use among patients with type 2 diabetes mellitus. METHODS: MEDLINE, EMBASE, and CENTRAL were searched for observational studies published between March 2013 and March 2026. Quality was assessed using the Risk of Bias In Non-Randomized Studies of Interventions (ROBINS-I) tool, alongside evaluation of pharmacoepidemiology-specific biases. RESULTS: A total of 17 studies (16 cohort and one nested case-control) were included. Based on ROBINS-I, seven studies had moderate, eight serious, and two critical risks of bias. Eleven studies had at least one pharmacoepidemiology-specific bias. For ventricular arrhythmias, estimates ranged from a protective effect (hazard ratio [HR] 0.20, 95% confidence interval [CI] 0.04-0.97) to a potential increased risk (odds ratio 1.87, 95% CI 0.89-3.95) with SGLT2i use. For cardiac arrest, estimates consistently reported a lower risk with estimates that ranged from HR 0.63 (95% CI 0.59-0.68) to HR 0.85 (95% CI 0.82-0.88). The only study on sudden cardiac death reported a potential risk reduction (HR 0.62, 95% CI 0.38-1.01). CONCLUSIONS: While the association between SGLT2i and ventricular arrhythmias remains inconsistent, the use of SGLT2i likely reduces cardiac arrest and may reduce sudden cardiac death, suggesting a possible protective effect on ventricular arrhythmias among patients with type 2 diabetes.
A 30-year-old patient was admitted to hospital for cholecystectomy with a diagnosis of complete obstruction of the cystic duct. The preoperative clinical and chemical findings were normal. Following cholecystectomy the patient recovered normally from the anaesthetic. Three hours later sudden cardiac arrest occurred. Necropsy revealed glycogen storage disease type I. Hypoglycaemia and metabolic acidosis had probably led to hypokalaemia which is considered as the cause of cardiac failure.
In three years 40 patients were resuscitated by ambulancemen after out-of-hospital cardiac arrest and survived to be discharged. Twenty-six of these had had circulatory arrest before an ambulance arrived and a further three had developed ventricular fibrillation before they were moved. Thirty-two patients were alive at the time of review six months to three and a half years later. Resuscitation by ambulancemen can be effective for patients with unheralded sudden cardiac arrest as well as for patients with recent myocardial infarction. Survivors of out-of-hospital ventricular fibrillation may have a favourable long-term prognosis.
BACKGROUND: The ring-like pattern of late gadolinium enhancement (RL-LGE) on cardiac magnetic resonance (CMR) has been proposed as a distinctive imaging marker of arrhythmogenic cardiomyopathy (ACM) with left ventricular (LV) involvement. However, the clinical characteristics and prognostic significance remain to be further clarified. OBJECTIVES: This study sought to assess the clinical profile, genetic background, and prognostic significance of RL-LGE in ACM with LV involvement. METHODS: In this observational cohort study, we included consecutive patients with a diagnosis of biventricular or left-dominant ACM (BIV-ACM or LD-ACM). RL-LGE was defined as subepicardial or midmyocardial LGE involving ≥3 contiguous LV segments on the same short-axis slice. The primary endpoint was a composite of sudden cardiac arrest, sustained ventricular tachycardia, or implantable cardioverter-defibrillator (ICD) interventions. RESULTS: Among 149 patients (mean age 36 ± 12 years, 66% male), RL-LGE was identified in 73 (49%), most frequently in association with DSP variants, with a higher prevalence in BIV-ACM (70%) than in LD-ACM (30%). Over a median follow-up of 31 months, 24 patients experienced the primary endpoint, 67% of whom had RL-LGE. In multivariable Cox regression, RL-LGE emerged as an independent predictor of the primary endpoint (HR: 2.47; 95% CI: 1.10-6.02; P = 0.042), along with nonsustained ventricular tachycardia (HR: 2.62; 95% CI: 1.17-6.41; P = 0.033), whereas genetic status did not provide additional prognostic information. Incorporating RL-LGE into the arrhythmogenic right ventricular cardiomyopathy risk model significantly improved its predictive performance (likelihood ratio test: P = 0.006). CONCLUSIONS: RL-LGE independently predicts arrhythmic events in ACM, regardless of genotype status, and refines the prognostic performance of traditional risk models. Its detection may aid in early recognition of high-risk patients and inform primary-prevention ICD therapy.
IMPORTANCE: Genetic diagnosis has become increasingly important to guide clinical decision-making for patients with dilated cardiomyopathy (DCM). Pathogenic or likely pathogenic (P/LP) missense variants in the gene RBM20 cause a highly penetrant arrhythmogenic DCM, but the role of RBM20 truncating variants (RBM20tvs) is unclear. OBJECTIVE: To assess the contribution of RBM20 variants to arrhythmogenic DCM. DESIGN, SETTING, AND PARTICIPANTS: In this cohort study, participants in the genome-first UK Biobank (UKB) and All of Us populations were evaluated to assess the etiologic fraction, natural history and penetrance of RBM20 variants. Retrospective data were collected from an international cohort of patients with DCM and RBM20 variants identified at centers of excellence for genetic heart disease and compared based on time to event. Study dates are not disclosed because the institutional review board did not authorize the sharing of this information. EXPOSURES: RBM20 variants were compared to known P/LP variants and variants of uncertain significance in RBM20 as well as titin truncating variants (TTNtvs). MAIN OUTCOMES AND MEASURES: Major ventricular arrhythmias, end-stage heart failure, and heart failure hospitalization as measured by medical record review (retrospective cohort) and diagnostic codes (UKB). RESULTS: Two main cohorts were studied for this project. In UK Biobank, a cohort of participants with RBM20tvs, RBM20 synonymous variants, and TTNtvs was studied. Of these 4249 participants, 1869 (44%) were male. The mean (SD) age at enrollment was 56 (8.2) years. In the RBM20 registry, of 179 patients, 105 (58.6%) were male, and the mean (SD) age at enrollment was 43.8 (19.1) years. A validation cohort from the All of Us biobank was also used. This consisted of 7002 participants, 4342 of whom (62.0%) were male, and the mean (SD) age was 52.7 (16.7) years. The etiologic fraction of RBM20 variants in arrhythmogenic DCM was 0.53 (95% CI, 0.32-0.67; P < .001). In genome-first biobanks, lifetime incidence of cardiomyopathy, heart failure, or major ventricular arrhythmia diagnosis was lower in participants with RBM20 variants than in those with TTNtvs (hazard ratio, 0.55; 95% CI, 0.36-0.84; P < .001). Patients with RBM20tvs and DCM presented to referral centers later in life than those with P/LP RBM20 and DCM (mean [SD], 53 [10] vs 34 [18] years; P < .001) and were less likely to have a family history of sudden cardiac arrest (2 of 10 [20%] vs 11 of 17 [65%]; P = .046) or cardiomyopathy (2 of 10 [20%] vs 14 of 18 [78%]; P < .001). There was no significant difference in age- and sex-adjusted incident major heart failure or arrhythmia events between patients with RBM20tv and DCM or those with P/LP RBM20 and DCM, though sex-adjusted lifetime hazard was reduced in those with RBM20tv and DCM (hazard ratio, 0.13; 95% CI, 0.03-0.56; P = .01). CONCLUSIONS AND RELEVANCE: This study found that RBM20 variants contributed to arrhythmogenic DCM phenotypes but conferred reduced lifetime disease penetrance compared to TTNtvs and milder disease severity alone than P/LP RBM20 variants. Their potential for additive interactions with other damaging variants should be considered in patients with DCM and their families.
1. Two types of hypoxic delta activity were observed in ECoG records of dogs subjected to exsanguination, sudden cardiac arrest resulting from ventricular fibrillation or mechanical asphyxiation, as well as during post-hypoxic recovery. They were polymorphous delta activity (PDA) and "standard slow complexes" (SSCs). 2. These two types of delta activity were found to differ from each other as to the shape of the potentials; their amplitude in monopolar and bipolar leads; the cortical areas in which the activity exhibited the highest amplitude; the degree of manifestation in the cortex and subcortical structures; their relation to activating influences; their dependence on the stage and character of hypoxia. 3. Analysis of EEG records of patients during and after hypoxia made it possible to distinguish both PDA and a type of delta activity similar to the SSCs observed in experimental animals. 4. It is suggested that the appearance of SSCs is determined by the activity of a pacemaker situated in the diencephalon and responding to pO2 changes, and that the mechanism of SSC generation is closer to that of monorhythmic, bilataerally synchronous delta waves observed in primary irritative or epileptogenic processes in the diencephalon.
BACKGROUND: Homozygous familial hypercholesterolemia (HoFH) is a leading cause of premature atherosclerotic cardiovascular disease (ASCVD) and early mortality if left untreated or inadequately treated. OBJECTIVE: This study presents 2 pediatric cases of early death from Pakistan due to familial hypercholesterolemia (FH) and provides a systematic review of similar cases reported globally. METHODS: Genetic analysis was conducted using next-generation sequencing to confirm pathogenic variants. For the systematic review, published reports of individuals with FH who died before the age of 18 years were identified. Data were extracted on demographic features, personal and family history, genetic variants, treatment given, and cause of death. RESULTS: Both patients, born to consanguineous families, presented with markedly elevated low-density lipoprotein cholesterol (LDL-C) levels (792 mg/dL [20.48 mmol/L] and 896 mg/dL [23 mmol/L], respectively), multiple xanthomas, and early-onset myocardial infarction, and died at the ages of 5 and 7 years, respectively. Their genetic analysis revealed a pathogenic frameshift variant in the LDLR gene: NM_000527.5: c.2416dupG (p.Val806GlyfsTer11). The systematic review included 12 studies reporting pediatric FH-related mortality. Common clinical features included tendon xanthomas, elevated LDL-C levels, family history, and early-onset ASCVD. Genetic testing was performed in a few cases, which revealed pathogenic variations in the LDLR gene. Most of the patients received inadequate lipid-lowering therapy. The most common causes of death were severe coronary artery disease, myocardial infarction, and sudden cardiac arrest. CONCLUSION: Our 2 cases and the accompanying systematic review identified additional cases of premature mortality. Collectively, these findings highlight diagnostic delays and inadequate treatment as common factors among patients who died prematurely.
BACKGROUND: In long QT syndrome, longer QT intervals indicate increased arrhythmic risk, and a rate-corrected QT interval (QTc) of ≥500 ms denotes high risk. Establishing similar associations in short QT syndrome (SQTS) remains elusive. OBJECTIVE: This study aimed to demonstrate that shorter QT intervals denote a higher risk of malignant arrhythmias in SQTS and to define the "high-risk" QTc value in SQTS. METHODS: Pooled analysis of patients treated in our institutions or those reported in the literature revealed 162 patients with SQTS and known symptomatic status; 57 of them (35.2%) had arrhythmic symptoms (sudden death, cardiac arrest, or malignant syncope). RESULTS: There was a significant inverse association between the QTc and arrhythmic symptoms (with a median QTc of 315.0 ms [interquartile range 300.5-338.0] among symptomatic patients vs 330.0 ms [interquartile range 312.5-355.0] among asymptomatic patients; P = .0023). Receiver operator characteristics analysis showed that shorter QTc values were associated with a higher risk (area under the curve 0.64 ± 0.04; P = .0024). When patients were grouped by QTc range, most of those with a QTc of ≤320 ms had malignant arrhythmic symptoms, whereas the reverse was true for those with a QTc of ≥320 ms. Male patients were overrepresented in the SQTS cohort and more so in the subgroup with malignant symptoms. CONCLUSION: This pooled analysis of patients with SQTS demonstrates that, among patients with congenital SQTS, a shorter QTc is associated with a higher risk of malignant ventricular arrhythmias. A QTc shorter than 320 ms correlates with a higher arrhythmic risk. Men seem to be at higher risk.
Stimulation of the carotid-body chemo-receptors by asphyxia during an apnoeic episode may contribute to the vagally mediated cardiac arrest and sudden death that sometimes occurs in man. Apnoeic asphyxia may be induced centrally or reflexly by stimulation of upper airways receptors. Conditions associated with apnoeic asphyxia and in which the risk is likely to be greatest include intubation, laryngoscopy and bronchoscopy; accidents involving underwater swimming; inhalation of sympathomimetic amines in aerosols by asthmatic patients; and chronic hypoventilation syndromes. These reflexes may be responsible for some victims of sudden infant death syndrome. Stimulation of the carotid bodies normally produces hyperventilation and bradycardia. When apnoea occurs centrally or reflexly, carotid chemoreceptor excitation resulting from asphyxia now causes a much enhanced bradycardia and even cardiac arrest, but paradoxically does not usually affect respiration. These reflexes and their interactions normally serve protective and purposeful functions, but may under certain circumstances become exaggerated and put the patient's life at risk.
AIMS: Calcium release channel deficiency syndrome (CRCDS) results from loss-of-function (LOF) variants in the RYR2-encoded type 2 ryanodine receptor (RyR2), predisposing patients to sudden cardiac arrest/death (SCA/SCD) without abnormalities on a stress electrocardiogram (ECG). Undetected CRCDS may underlie idiopathic ventricular fibrillation (IVF) and sudden unexplained death in the young (SUDY). We aimed to determine the prevalence of potential CRCDS-causative RYR2 variants in IVF and SUDY. METHODS AND RESULTS: We reviewed clinical evaluation and RYR2 genetic analysis of 169 IVF patients and 279 SUDY victims. Only ultra-rare (<0.005% in gnomAD) nonsynonymous RYR2 variants were considered potentially pathogenic. Among IVF patients, 6/169 (3%) overall-and 6/67 (9%) with exertion-related SCA-harboured an RYR2 variant and represent potential CRCDS cases. All exhibited normal resting and stress ECGs. Genetic analysis revealed six distinct RYR2 variants, two previously characterized as LOF. In SUDY, 31/279 victims (11%) had a RYR2 variant (30 unique variants), predominantly observed in exertion-related SCD 20/83 (24%) vs. rest-related 11/196 (6%). Of the 14 SUDY victims with functionally characterized RYR2 variants, five (2% of total cohort) had a LOF variant; among the 56 exertion-related SUDY cases, four (7%) had a LOF variant. CONCLUSION: CRCDS may account for 3% of IVF overall and 9% of exertion-related SCA in IVF. Ultra-rare RYR2 variants may underlie up to 11% of SUDY, with 65% of RYR2-positive cases occurring during exertion. LOF-RYR2 variants may contribute to ≥7% of exercise-associated SUDY. Accurate identification of the underlying ryanodinopathy is essential for clinical management of affected patients.
Coronary artery aneurysm in childhood is a rare disease and has in most cases been ascribed to infantile periarteritis nodosa (IPN). In recent years a mucocutaneous lymph node syndrom (MLNS) has been found almost exclusively in Japan first described by Kawasaki 1967; this disease frequently involves the coronary arteries and myocardium. Four cases with coronary aneurysms are presented from Sweden and seem to be first described from Scandinavia. Three of these patients died a sudden death with cardiac arrest. Since MLNS and IPN have identical clinical and pathological features, we suggest that MLNS and IPN constitute a pathologic entity and that to separate them on a clinical or histological basis is nonsensical. The risk of coronary aneurysm and possible sudden death must be considered in patients with uncharacteristic symptoms including prolonged fever, conjunctivitis, exanthema, lesions in the oral mucosa, elevated sedimintation rate, and leukocytosis.
BACKGROUND: Arrhythmogenic and dilated cardiomyopathies (ACM and DCM, respectively) are genetically heterogeneous disorders of the right and/or left ventricles associated with an increased risk of major arrhythmic events (MAE) and end-stage heart failure (ESHF). In arrhythmogenic right ventricular cardiomyopathy (ARVC), the presence of >1 pathogenic or likely pathogenic (P/LP) variant is associated with worse outcomes. Whether this phenomenon occurs for non-desmosomal arrhythmogenic left ventricular cardiomyopathy (ALVC)/DCM genes is unknown. OBJECTIVE: This study aimed to evaluate the impact of single vs multiple P/LP variants on arrhythmic and heart failure outcomes across the ACM/DCM genetic spectrum. METHODS: We retrospectively analyzed 1054 genotype-positive patients with ≥1 P/LP variant in a definitive or strong evidence ARVC- or ALVC/DCM-causative gene. Primary endpoints were MAE (sustained ventricular tachycardia, ventricular fibrillation, aborted cardiac arrest, appropriate implantable cardioverter-defibrillator therapy, and sudden cardiac death) and ESHF (transplant or heart failure death). RESULTS: Of the 1054 patients, 27 (3%) harbored >1 P/LP variants (21 with ≥1 ALVC/DCM gene; 6 with >1 ARVC gene). MAE occurred in 20% of single-variant patients compared with 48% and 50% of those with >1 P/LP variants in ≥1 ALVC/DCM- and >1 ARVC-susceptibility gene(s), respectively. ESHF occurred in 9%, 29%, and 17% of patients, respectively. On adjusted analysis, >1 P/LP variants in ≥1 ALVC/DCM-susceptibility (MAE hazard ratio [HR], 2.46 [1.28-4.72]; P = .01 and ESHF HR, 3.15 [1.35-7.37], P = .01) and >1 ARVC-susceptibility gene(s) (MAE HR, 2.67 [1.28-8.72], P = .03) were independent predictors of the primary endpoints. CONCLUSION: Multiple P/LP variants confer an increased risk of arrhythmic events and heart failure across the ACM/DCM spectrum.
The intracardiac administration of medications in cardiac arrest is advocated when an intravenous route cannot be established. Although warnings of complications of this mode of therapy are reiterated throughout the literature, their careful documentation is lacking. Paramedics were trained to administer intracardiac medications, under strict criteria, in patients with prehospital sudden cardiac death. Long-term survivors who received intracardiac medications from paramedics were compared to a control group resuscitated by paramedics with intravenous medications alone. By far, the patients who received intracardiac medications were more nearly refractory to resuscitation because of the criteria for intracardiac medication use. Potential complications of the intracardiac route were identified and sought. However, complications were no more common in this group of patients than in the control group. Paramedics can successfully administer intracardiac medications when indicated.
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