Tests for the identification of reflex syncope mechanism.

INTRODUCTION: Treatment efficacy of reflex syncope is mainly related to the mechanism underlying syncope rather than its etiology or clinical presentation. The predominant mechanism underlying reflex syncope can be assigned to hypotensive or to bradycardic phenotypes. AREAS COVERED: Methodology and diagnostic criteria of the most useful tests for the identification of hypotensive and bradycardic phenotypes are discussed. Diagnostic tests for the hypotensive phenotype include office blood pressure measurement with active standing test, home, and wearable blood pressure monitoring, 24-h ambulatory blood pressure monitoring and tilt table test. Diagnostic tests for the bradycardic phenotype include carotid sinus massage, tilt table test and prolonged ECG monitoring. EXPERT OPINION: In reflex syncope, the documentation of bradycardia/asystole during a syncopal episode does not rule out the possibility that a preceding or parallel hypotensive reflex plays an important role. Similarly, even when a hypotensive mechanism is established, the possibility of an associated cardioinhibitory reflex should be investigated. Investigating the mechanism of reflex syncope is mandatory in patients with severe recurrent episodes, with the final aim to develop a personalized treatment strategy. Recent trials have demonstrated the benefits of personalized mechanism-based therapy, thus highlighting the importance of a comprehensive assessment of the mechanisms underlying syncope.

Hyperbaric oxygen for treatment of long COVID-19 syndrome (HOT-LoCO): protocol for a randomised, placebo-controlled, double-blind, phase II clinical trial.

INTRODUCTION: Long COVID-19, where symptoms persist 12 weeks after the initial SARS-CoV-2-infection, is a substantial problem for individuals and society in the surge of the pandemic. Common symptoms are fatigue, postexertional malaise and cognitive dysfunction. There is currently no effective treatment and the underlying mechanisms are unknown, although several hypotheses exist, with chronic inflammation as a common denominator. In prospective studies, hyperbaric oxygen therapy (HBOT) has been suggested to be effective for the treatment of similar syndromes such as chronic fatigue syndrome and fibromyalgia. A case series has suggested positive effects of HBOT in long COVID-19. This randomised, placebo-controlled clinical trial will explore HBOT as a potential treatment for long COVID-19. The primary objective is to evaluate if HBOT improves health-related quality of life (HRQoL) for patients with long COVID-19 compared with placebo/sham. The main secondary objective is to evaluate whether HBOT improves endothelial function, objective physical performance and short-term HRQoL. METHODS AND ANALYSIS: A randomised, placebo-controlled, double-blind, phase II clinical trial in 80 previously healthy subjects debilitated due to long COVID-19, with low HRQoL. Clinical data, HRQoL questionnaires, blood samples, objective tests and activity metre data will be collected at baseline. Subjects will be randomised to a maximum of 10 treatments with hyperbaric oxygen or sham treatment over 6 weeks. Assessments for safety and efficacy will be performed at 6, 13, 26 and 52 weeks, with the primary endpoint (physical domains in RAND 36-Item Health Survey) and main secondary endpoints defined at 13 weeks after baseline. Data will be reviewed by an independent data safety monitoring board. ETHICS AND DISSEMINATION: The trial is approved by the Swedish National Institutional Review Board (2021-02634) and the Swedish Medical Products Agency (5.1-2020-36673). Positive, negative and inconclusive results will be published in peer-reviewed scientific journals with open access. TRIAL REGISTRATION NUMBER: NCT04842448.

Acute myocardial infarction in a patient with congenitally corrected transposition of the great arteries and complex coronary anatomy-a case report.

Background: Congenitally corrected transposition of the great arteries (ccTGA) is a rare congenital heart anomaly with atrioventricular and ventriculoarterial discordance that is often associated with other cardiac and coronary artery anomalies. Here, we report a case of a patient with ccTGA and non-ST elevation myocardial infarction (NSTEMI) with challenging coronary anatomy that was treated with stress-perfusion cardiac magnetic resonance imaging (spCMR) guided percutaneous coronary intervention (PCI). Case summary: A 46-year-old male smoker with ccTGA, dyslipidaemia, diabetes Type 2 managed with dietary restrictions and a family history of premature myocardial infarction, presented with typical chest pain, elevated cardiac troponin levels and ECG-changes indicative of ischaemia. The patient was diagnosed with NSTEMI and underwent initial urgent coronary angiography (CA) without apparent significant stenosis, although the right coronary artery (RCA) could not be selectively investigated. The patient had coronary anatomy 1R-2LCX according to the Leiden convention, which is the usual anatomy in patients with ccTGA. Despite this, CA was challenging due to the different anatomy compared with individuals with normally positioned great vessels. The patient remained highly symptomatic with chest pain at moderate exertion. To improve identification of the anatomic location and extent of ischaemia, we performed spCMR with adenosine. This revealed a limited septal infarction (likely embolic) in the right ventricle and reversible ischaemia in two inferior right ventricular segments. A second angiography, selectively investigating RCA demonstrated a significant stenosis in the distal RCA that was successfully treated with a drug-eluting stent. Fractional flow reserve (FFR) measurements of the left coronary arteries demonstrated hemodynamically non-significant stenosis. The patient's symptoms resolved, and he remained asymptomatic at one month follow-up. Discussion: This ccTGA patient had multiple risk factors for coronary artery disease and presented with NSTEMI. Diagnosis and treatment were challenging due to complex cardiac anatomy and associated different origins of the coronary arteries. We highlight the importance of careful evaluation of the coronary anatomy and functional testing using for example spCMR and FFR to target the culprit coronary vessel(s) in ccTGA complicated by NSTEMI.

Association between demographic, organizational, clinical, and socio-economic characteristics and underutilization of cardiac resynchronization therapy: results from the Swedish Heart Failure Registry.

AIMS: Cardiac resynchronization therapy (CRT) improves outcomes in heart failure (HF) but may be underutilized. The reasons are unknown. METHODS AND RESULTS: We linked the Swedish Heart Failure Registry to national registries with ICD-10 (International Classification of Diseases-10th Revision) co-morbidity diagnoses and demographic and socio-economic data. In patients with EF ≤39% and NYHA II-IV, we assessed prevalence of CRT indication and CRT use. In those with CRT indication, we assessed the association between 37 potential baseline covariates and CRT non-use using multivariable generalized estimating equation (GEE) models. Of 12 807 patients (mean age 71 ± 12 years, 28% female), 841 (7%) had CRT, 3094 (24%) had an indication for but non-use of CRT, and 8872 (69%) had no indication. Important variables independently associated with CRT non-use were: HF duration <6 months [risk ratio (RR) 1.21, 95% confidence interval (CI) 1.17-1.24]; non-cardiology planned follow-up (RR 1.14, 95% CI 1.09-1.18); age >75 years (RR 1.13, 95% CI 1.09-1.18); non-cardiology care at baseline (RR 1.10, 95% CI 1.07-1.14); small-town non-university centre (RR 1.08, 95% CI 1.05-1.12); female sex (RR 1.07 95% CI 1.03-1.10) (all P < 0.05); as was absence of AF, living alone; psychiatric diagnosis; smoking; and non-use of HF drugs. Education, income, cancer, or HF characteristics were not independently associated with CRT non-use. CONCLUSION: In this population-wide HF registry, CRT was underutilized. Non-use was associated mostly with demographic and organizational, but not clinical or socio-economic factors. This calls for programmes to raise awareness of CRT indications and improve access and referrals to cardiology specialists.

Effect of physical training on the proportion of slow-twitch type I muscle fibers, a novel nonimmune-mediated mechanism for muscle impairment in polymyositis or dermatomyositis.

OBJECTIVE: To compare muscle fiber type composition and muscle fiber area in patients with chronic polymyositis or dermatomyositis and healthy controls, and to determine whether physical training for 12 weeks could alter these muscle characteristics. METHODS: Muscle fiber type composition and muscle fiber area were investigated by biochemical and immunohistochemistry techniques in repeated muscle biopsy samples obtained from 9 patients with chronic myositis before and after a 12-week exercise program and in healthy controls. Muscle performance was evaluated by the Functional Index (FI) in myositis and by the Short Form 36 (SF-36) quality of life instrument. RESULTS: Before exercise, the proportion of type I fibers was lower (mean +/- SD 32% +/- 10%) and the proportion of type IIC fibers was higher (3% +/- 3%) in patients compared with healthy controls. After exercise, percentage of type I fiber increased to 42% +/- 13% (P < 0.05), and type IIC decreased to 1% +/- 1%. An exercise-induced 20% increase of the mean fiber area was also observed. The functional capacity measured by the FI in myositis and the physical functioning subscale of the SF-36 increased significantly. Improved physical functioning was positively correlated with the proportion of type I fibers (r = 0.88, P < 0.01) and type II muscle fiber area (r = 0.70, P < 0.05). CONCLUSION: Low muscle endurance in chronic polymyositis or dermatomyositis may be related to a low proportion of oxidative, slow-twitch type I fibers. Change in fiber type composition and increased muscle fiber area may contribute to improved muscle endurance and decreased muscle fatigue after a moderate physical training program.