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This article describes the case of a 40-year-old individual who presented with fulminant myocarditis. Initial ECG displayed sinus tachycardia with a heart rate of 117 bpm, QS complexes in leads V1-V3, ST-segment depression in leads II, III, aVF, V5-V6, and ST-segment elevation >0.2 mV in leads V1 through V3. The initial clinical assessment suggested an acute anteroseptal myocardial infarction. However, subsequent diagnostic evaluation through coronary angiography disclosed that the coronary arteries were normal. Therefore, clinicians should carefully consider the differential diagnosis between these conditions, as their management strategies differ markedly. Two hours after admission, the patient unexpectedly developed syncope. The ECG findings were consistent with the typical characteristics of bidirectional ventricular tachycardia. Our report described the appearance and morphology as well as mechanism of bidirectional ventricular tachycardia in detail. Additionally, we delineate differential diagnoses for disease that can cause bidirectional ventricular tachycardia, such as aconite poisoning, digoxin overdose, immune checkpoint inhibitor (ICI), myocardial ischemia, and hereditary channelopathies, such as catecholaminergic polymorphic ventricular tachycardia (CPVT) and Andersen-Tawil syndrome. Therefore, clinicians should recognize this ECG finding immediately and initiate appropriate treatment promptly as these measures may be vital in saving the patient\'s life.

Fetal autoimmune atrioventricular block (AVB) is a rare but potentially life-threatening condition. It results from the passage of maternal anti-SSA/Ro or Anti SSB/La auto-antibodies into the fetal circulation, leading to inflammation and fibrosis of the AV node and often to irreversible damage. Besides AVB, these antibodies can also cause cardiomyopathies, but there is no evidence linking them to tachyarrhythmias. We present the case of a patient with significant risk factors for fetal AVB: a prior history of hydrops fetalis, high anti-SSA/Ro antibody levels and hypothyroidism. In this case, the use of dexamethasone and intravenous immunoglobulin may have contributed to reversing the first-degree atrioventricular block detected at 19 weeks of gestation. Additionally, at 21 weeks, the fetus developed a tachyarrhythmia that needed treatment with flecainide. Soon after the birth, the newborn underwent ECG Holter and Wolff-Parkinson-White Syndrome (WPWS) was diagnosed. To our knowledge, the coexistence of fetal AVB and WPWS has never been described.

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UNASSIGNED: Relative-tachycardia (RT), a phenomenon of unproportionately high heart-rate elevation in response to fever, has been previously attributed to unfavourable outcomes in severe-inflammatory-response-syndrome (SIRS). Relative heart-rate to body-temperature ratio (RHR) and its prognostic associations in patients with severe and critical coronavirus disease 2019 (COVID-19) have not been investigated.
UNASSIGNED: We retrospectively analyzed heart-rate and body-temperature data at admission in patients who were hospitalized due to COVID-19 at a tertiary center from March 2020 to June 2021. After excluding patients with known heart rate affecting medications (beta-blockers and other antiarrhythmics) and atrial fibrillation, a total of 3490 patients were analyzed. Patients were divided into quartiles based on RHR on admission, with patients belonging to the 1st quartile designated as having relative-bradycardia (RB) and patients belonging to 4th quartile designated as having RT. Comparisons with baseline clinical characteristics and the course of treatment were done.
UNASSIGNED: There were 57.5% male patients. Median age was 69 years. Most patients had severe or critical COVID-19 at admission. Median heart-rate at the time of hospital admission was 90/min, median body-temperature was 38 °C, and median RHR was 2.36 with interquartile-range 2.07-2.65. RB in comparison to middle-range RHR was significantly associated with older age, higher comorbidity burden, less severe COVID-19 and less pronounced inflammatory profile, and in comparison to RT additionally with higher frequency of hyperlipoproteinemia but lower frequency of obesity. RT in comparison to middle-range RHR was significantly associated with younger age, more severe COVID-19, lower comorbidity burden, lower frequency of arterial hypertension, higher frequency of diabetes mellitus, and more pronounced inflammatory profile. In multivariate analyses adjusted for clinically meaningful parameters, RB patients experienced more favorable survival compared to RT, whereas RT patients experienced higher mortality in comparison to RB and middle-range RHR patients, independently of older age, male sex, higher comorbidity burden and higher COVID-19 severity.
UNASSIGNED: Heart rate and axillary temperature are an indispensable part of a clinical exam, easy to measure, at effectively no cost. RT at admission, as a sign of excessive activation of the sympathetic nervous system, is independently associated with fatal outcomes in COVID-19 patients.

UNASSIGNED: This study examined the clinical characteristics, genetic basis, healthcare utilisation and costs of catecholaminergic ventricular tachycardia (CPVT) patients from a Chinese city.
UNASSIGNED: This was a territory-wide retrospective cohort study of consecutive CPVT patients at public hospitals or clinics in Hong Kong. Healthcare resource utilisation for accident and emergency (A&E), inpatient and outpatient attendances were analysed over 19 years (2001-2019) followed by calculations of annualised costs (in USD).
UNASSIGNED: Sixteen patients with a median presentation age (interquartile range (IQR) of 11 (9-14) years old) were included. Fifteen patients (93.8%) were initially symptomatic. Ten patients had both premature ventricular complexes (PVCs) and ventricular tachycardia/fibrillation (VT/VF). One patient had PVCs without VT/VF. Genetic tests were performed on 14 patients (87.5%). Eight (57.1%) tested positive for the ryanodine receptor 2 (RyR2) gene. Seven variants have been described elsewhere (c.14848G > A, c.12475C > A, c.7420A > G, c.11836G > A, c.14159T > C, c.10046C > T and c.7202G > A). c.14861C > G is a novel RyR2 variant not been reported outside this cohort. Patients were treated with beta-blockers (n = 16), amiodarone (n = 3) and verapamil (n = 2). Sympathectomy (n = 8) and implantable-cardioverter defibrillator implantation (n = 3) were performed. Over a median follow-up of 13.3 years (IQR: 8.4-18.1) years, six patients exhibited incident VT/VF. At the patient level, the median (IQR) annualised costs for A&E, inpatient and outpatient attendances were $ 66 (40-95), $ 10521 (5240-66887) and $ 791 (546-1105), respectively.
UNASSIGNED: All patients presented before the age of 19. The yield of genetic testing was 57%. The most expensive attendance type was inpatient stays, followed by outpatients and A&E attendances.

UNASSIGNED: Sodium-glucose cotransporter 2 inhibitors (SGLT2i) are a class of widely used hypoglycemic agents for the treatment of type 2 diabetes mellitus (T2DM). In addition to lowering blood glucose, SGLT2i protects the heart and kidney, significantly reduces cardiovascular events, and delays the progression of heart failure and chronic kidney disease. However, previous studies have not exhaustively discussed the association between SGLT2i and the risk of developing cardiac arrhythmias. The purpose of this study is to assess the association of SGLT2i with cardiac arrhythmias in patients with T2DM and without T2DM in cardiovascular outcome trials (CVOTs).
UNASSIGNED: We performed a meta-analysis and systematic review of CVOTs that compared SGLT2i with placebo. MEDLINE, Web of Science, The Cochrane Library and Embase were systematically searched from inception to December 2022. We included CVOTs reporting cardiovascular or renal outcomes with a follow-up duration of at least 6 months.
UNASSIGNED: A total of 12 CVOTs with 77,470 participants were included in this meta-analysis (42,016 SGLT2i vs 35,454 control), including patients with T2DM, heart failure (HF), or chronic kidney disease (CKD). Follow-up duration ranged from 9 months to 5.65 years. Medications included empagliflozin, canagliflozin, dapagliflozin and ertugliflozin. SGLT2i were associated with a lower risk of tachycardia (risk ratio (RR) 0.86; 95% confidence interval (CI) 0.79-0.95), supraventricular tachycardia (SVT; RR 0.84; 95% CI 0.75-0.94), atrial fibrillation (AF; RR 0.86; 95% CI 0.75-0.97) and atrial flutter (AFL; RR 0.75; 95% CI 0.57-0.99) in patients with T2DM, HF and CKD. SGLT2i could also reduce the risk of cardiac arrest in CKD patients (RR 0.50; 95% CI 0.26-0.95). Besides, SGLT2i therapy was not associated with a lower risk of ventricular arrhythmia and bradycardia.
UNASSIGNED: SGLT2i therapy is associated with significantly reduced the risk of tachycardia, SVT, AF, and AFL in patients with T2DM, HF, and CKD. In addition, SGLT2i could also reduce the risk of cardiac arrest in CKD patients. Further researches are needed to fully elucidate the antiarrhythmic mechanism of SGLT2i.

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Leaves of the Khat plant are widely consumed in the Horn of Africa, Yemen and the Jazan region of Saudi Arabia. I have investigated the mode of cardiovascular and autonomic actions of the stimulant cathine from Khat in terms of direct or indirect adrenergic actions in anaesthetised male and female rats, and in isolated tissues. Male and female rats were anaesthetised with pentobarbitone and changes in diastolic blood pressure and cardioaccelerator responses were examined in vehicle-treated or chemically sympathectomised rats. Cathine produced marked tachycardia and smaller blood pressure responses in vehicle-treated animals, with significant rises in heart rate occurring at cathine (0.1 mg/kg). In sympathectomised rats, cardiac actions were greatly attenuated in both male and female animals, with no differences between male and female rats. Although pressor responses to cathine were relatively small, sympathectomy significantly reduced these responses in female, but not male, rats. In rat aorta and spleen, cathine produced almost no direct contractions. It is concluded that cathine acts predominantly indirectly, presumably by the release of noradrenaline, in both male and female rats to produce cardiovascular actions. This may have implications for adverse cardiovascular actions of consumption of the plant Khat, particularly with dried Khat, in which actions of cathine may predominate over those of cathinone.

BACKGROUND: Tachycardia-induced cardiomyopathy (TIC) is a reversible cardiomyopathy with ventricular dysfunction caused by tachyarrhythmias. Notably, atrial fibrillation (AF) is the most common causal arrhythmia leading to TIC. However, the risk factors for the development of TIC due to AF remain unclear. This study aimed to identify the associated factors of TIC due to AF.
METHODS: Persistent AF patients with heart rate (HR) ≥100 beats per minute who underwent initial catheter ablation were enrolled in this study. TIC was diagnosed as left ventricular ejection fraction (LVEF) < 50% during AF rhythm, which was recovered after the restoration of sinus rhythm. Non-TIC was defined as LVEF ≥ 50% despite AF rhythm. The patient backgrounds were compared between the TIC group and the non-TIC group to reveal the contributing factors of TIC.
RESULTS: The TIC group comprised 57 patients, while the non-TIC group consisted of 101 patients. The TIC group was younger than the non-TIC group (median 64 vs. 70, p = 0.006). Male sex was more frequent in the TIC group than the non-TIC group (82.5% vs. 58.4%, p = 0.003). HR was higher in the TIC group than in the non-TIC group (median 130 bpm vs. 111 bpm, p < 0.001). The number of smokers was significantly higher in the TIC group than in the non-TIC group (p < 0.001). Multivariable analysis demonstrated that higher HR (odds ratio [OR]: 1.74; 95% confidence interval [CI]: 1.37-2.21; p < 0.001) and current smokers (OR: 5.27; 95% CI: 1.60-17.4; p = 0.006) were the independent factors leading to TIC.
CONCLUSIONS: Higher HR and current smokers were independent risk factors for the development of TIC due to AF.