Frequency and predictors of thin-cap fibroatheroma progression: a comprehensive and dynamic in-vivo OCT study

Purpose

To assess the evolution of thin-cap fibroatheroma (TCFA) and to explore predictors for its progression by using optical coherence tomography (OCT) in patients with acute coronary syndrome (ACS).

Methods

We enrolled ACS patients with non-culprit TCFA at baseline and corresponding OCT images at follow-up of 9 to 15 months. Clinical, angiographic and OCT data were collected and analyzed according to established methods. TCFA was defined as a lipid plaque with maximum lipid arc >90° and fibrous cap thickness <65μm. Considering the resolution of OCT, the regression of TCFA was defined as an increase of fibrous cap thickness >10μm. Inversely, TCFA progression was defined as a decrease, constant or ≤10μm increase of fibrous cap thickness.

Results

41 patients with 55 non-culprit TCFAs were taken into final analysis. 17 patients (41.5%) had patient-level progression and 22 TCFAs (40.0%) progressed at plaque-level with a median follow-up duration of 371 days. 11 (20.0%) of the 55 TCFAs happened subclinical rupture at follow-up, including 10 with the formation a new layer and 1 without the detection of the new layer. Besides, another patient suffered re-myocardial infarction because of the rupture of TCFA induced acute thrombosis and lumen occlusion during follow-up. The baseline clinical and angiographic characteristics were similar between the two cohorts. The progression group had a significantly higher prevalence of macrophage infiltration and vasa vasorum at baseline than the non-progression group (Figure 1). Multivariate analysis identified macrophage infiltration (odds ratio [OR]: 5.30; 95% confidence interval [CI]: 1.01 to 27.91; p=0.049]) as the independent predictor of TCFA progression. When it came to the evolution of lesion morphology and lipid components, the progression cohort had a higher percent change of lumen stenosis and lipid length (Figure 2).

Conclusions

About 40% of non-culprit TCFAs in ACS patients progressed in fibrous cap thickness at a median interval of 1 year. Macrophage infiltration was the independent predictor of non-culprit TCFA progression. The progression of fibrous cap thickness was usually accompanied with an aggressive evolution of other lesion characteristics.

Funding Acknowledgement

Type of funding sources: Foundation. Main funding source(s): the National Key R&D Program of China Baseline OCT characteristicsPercent change of lesion morphology

Comparison of peripheral artery plaque characteristics between ACS patients with plaque rupture and plaque erosion in culprit coronary artery: an OCT and ultrasound study

Background

Recent research has found that the characteristics of peripheral arterial plaque are related to the increased risk of cardiovascular disease, however, the relationship of plaque characteristics between peripheral artery and coronary is still unknown.

Purpose

To assess the correlation between coronary plaque characteristics assessed by optical coherence tomography (OCT) and peripheral artery plaque characteristics assessed by ultrasound.

Methods

150 patients with acute coronary syndrome (ACS) underwent coronary angiography were prospectively enrolled. OCT imaging of culprit vessel were performed during the procedure and ultrasound examination of bilateral carotid, iliofemoral and popliteal arteries was performed during hospitalization after procedure. Panvascular disease was defined as the presence of observable plaques in two or more vascular beds. Patients were divided into plaque rupture (PR) group and plaque erosion (PE) group according to culprit plaque characteristics on OCT.

Results

There were 132 (88%) ACS patients had panvascular disease in which 36 (24%) with generalized atherosclerosis (4 sites) and the prevalence of panvascular atherosclerosis in PR group was significantly higher than in PE group especially in carotid arteries and iliofemoral arteries (Figure 1, Figure 2). Compared to PE group, PR group had higher carotid plaque score (p=0.001) which indicates more plaques and severer atherosclerosis. Moreover, there were larger intima-media thickness (IMT) of iliofemoral arteries (6.9±1.4mm vs. 6.5±1.1mm, p=0.036) and more calcified plaques in PR group.

Conclusions

Panvascular disease is highly prevalent in ACS patients especially in patients with plaque rupture in culprit vessel, in which more than half of the patients had plaques in more than 3 sites of vascular beds. In addition, patients with plaque rupture had thicker iliofemoral IMT and higher panvascular atherosclerosis burden, which indicates that characteristics of coronary plaques are the focal expression of plaques in the whole panvcascular system.

Funding Acknowledgement

Type of funding sources: Public grant(s) – National budget only. Main funding source(s): National Key R&D Program of China Figure 1. Prevalence of panvascular disease in ACSFigure 2. Comparison of peripheral artery plaques

Prevalence, predictors, and clinical prognosis of macrophage infiltrates in patients with ST-segment elevation myocardial infarction caused by plaque erosion as assessed by OCT

Background

Autopsy series showed that one of most common plaque phenotypes underlying coronary thrombi was plaque erosion. Identification of erosion may permit a less invasive management. Chronic inflammation is a common process in atherosclerosis. The severity of plaque inflammation can be assessed by optical coherence tomography (OCT) defined macrophages density. The impact of macrophage infiltrates (MØI) in ST-segment elevation myocardial infarction (STEMI) patients caused by plaque erosion was still unknown.

Purpose

The aim of this study was to evaluate plaque morphology and clinical prognosis associated with MØI as assessed by optical coherence tomography in STEMI patients caused by plaque erosion.

Methods

From October 2014 to December 2017, 1561 STEMI with OCT imaging before percutaneous coronary intervention were enrolled in this study. Finally, 312 STEMI patients caused by plaque erosion were split into two group according to the presence of MØI in culprit eroded plaques.

Results

163 (52.2%) STEMI patients presented plaque erosion with MØI, whereas 149 (47.8%) patients had no evidence of MØI. MØI were more frequency appeared in older patients (p=0.015). The severity and vulnerability of culprit lesions were higher in patients with MØI characterized by more aggressive and vulnerable features. Patients with MØI had worse long-term prognosis, compared with patient without MØI, mainly driven by a higher rate of target lesion revascularization (p=0.046), especially in STEMI patients presented plaque erosion with intensive antiplatelet therapy (p=0.035).

Conclusions

In the present study, we demonstrated that macrophage infiltrates at the site of erode plaques were associated with severity and vulnerability of culprit lesions. The long-term prognosis in patients with MØI were poorer especially in patients without stent implantation.

Funding Acknowledgement

Type of funding sources: None. Study flow chartPredictors of plaque erosion with MØI

Gender-specific difference of clinical and plaque characteristics in myocardial infarction with non-obstructive artery (MINOCA): insights from optical coherence tomography

Background

To date, sparse data are available with regard to gender differences in coronary plaque morphology and composition as underlying mechanism of MINOCA.

Purpose

To assess the differences in coronary plaque morphology in culprit lesion between women and men with MINOCA using intravascular optical coherence tomography.

Methods

Totally, 7404 consecutives acute myocardial infarction patients who underwent emergency coronary angiography between 2016 and 2019 were screened. MINOCA were identified in 292 patients (mean age: 72.6% male, 54.1% with ST-segment elevation). Optical coherence tomography was performed in 190 patients (men, n=142).

Results

Women with MINOCA were older (62.5±10.6 vs. 54.0±11.5, P<0.001) and more over 55 years (75.3% vs. 43.6%, P<0.001). Although women with MINOCA more frequently presented with NSTEMI (56.8% vs. 41.7%, P=0.025) and prior coronary artery disease (CAD) (33.3% vs. 6.3%, P<0.001), they were less likely smoker (27.2% vs. 58.8%, P<0.001). There was no significant difference in incidence of plaque rupture, erosion and calcified nodule between men and women. However, women were more likely to have thin-cap fibroatheroma (TCFA) (39.6% vs. 22.5%, P=0.025).

Conclusion

Women with MINOCA were older, more frequently presented with NSTEMI and less smoking compared to men. Besides, more TCFA were observed in women.

Funding Acknowledgement

Type of funding sources: None. Clinical and OCT plaque profilesProportion of clinical and OCT profiles

[Clinical and pathological features of Dubin-Johnson syndrome]

Objective: To explore the clinical and pathological features of Dubin-Johnson syndrome. Methods: The clinical and pathological characteristics of 18 cases of Dubin-Johnson syndrome diagnosed in the Department of Pathology of the Third Affiliated Hospital of Sun Yat-sen University from 2008 to 2018 were analyzed. Related literature was reviewed. Results: There were 15 male and three female patients. The male-to-female ratio was 5∶1. The age of the patients ranged from 17 to 73 years (median 24 years). Common clinical manifestations were jaundice, anorexia, and abnormal liver function tests. The pathological feature was the deposition of dark brown particles in the hepatocytes, especially those around the central veins. Conclusions: Dubin-Johnson syndrome mainly occurs in young people. The characteristic pathological changes are the deposition of dark brown particles in the hepatocytes around the central veins of the liver. The diagnosis of Dubin-Johnson syndrome mainly relies on clinical manifestations, laboratory examinations, histopathological examinations and genetic testing. The understanding of Dubin-Johnson syndrome can help reduce the rates of missed diagnosis and misdiagnosis of the disease.

Plasma metabolite changes in anestrous dairy cows with negative energy balance identified using 1H NMR technology

ABSTRACT The objective of the present study was to investigate the different plasma metabolites between anestrus and estrus postpartum dairy cows and to provide a theoretical basis for prevention of anestrus in dairy farm cows. In the experiment, one hundred and sixty-seven Holstein dairy cows were selected with similar age and parity. According to the concentration of β-hydroxybutyric acid, non-esterified fatty acids and glucose in plasma during 14 to 21 days in milk, all dairy cows were determined as having a status of energy balance. According to the results of clinical symptom, rectal and B ultrasound examination at 60 to 90 days postpartum, these cows were divided into twenty estrus and twenty-four anestrus group, other dairy cows were removed. 1H nuclear magnetic resonance technology was utilized to detect the plasma metabolites changes and screen different plasma metabolites between anestrus and estrus cows. Ten different metabolites including alanine, glutamic acid, asparagine, creatine, choline, phosphocholine, glycerophosphocholine, low-density lipoprotein, and very-low-density lipoprotein were significantly decreased in anestrous cows compared with estrous cows. Metabolic pathway analyses indicated that differential metabolites were primarily involved in amino acid and glycerophospholipid metabolism. These metabolites and their enrichment pathways indicate that reduced steroid hormone synthesis precursors result in lower levels of estradiol and progesterone and cause anestrus in negative energy balance. These data provide a better understanding of the changes that may affect estrus of postpartum dairy cows at NEB status and lay the ground for further research.

Successful removal of a trapped epidural catheter facilitated by using a nickel/titanium alloy (nitinol) suture as a guidewire

Epidural catheters are often used in the provision of surgical anaesthesia and analgesia. These catheters need to be removed after a certain period, but difficulties may be encountered during this process. We present a case of difficult epidural catheter removal in an elderly woman who had undergone surgery for reduction and internal fixation of a comminuted intertrochanteric fracture at the left femur under combined spinal epidural anaesthesia. Anaesthesia was satisfactory during the operation; however, initial attempts to remove the catheter at the end of the procedure was met with significant resistance. Normal saline (5 ml) was injected through the catheter without difficulty, suggesting that the catheter was likely trapped and compressed but not obstructed. A nickel/titanium memory alloy suture was used as a guidewire to remove the catheter without damaging it. This case was analysed subsequently, and the management of future problematic removals is discussed herein. This article aims to raise awareness of, and to explore techniques for managing difficult epidural catheter removal.

Constraints on Cosmic Strings Using Data from the Third Advanced LIGO-Virgo Observing Run

We search for gravitational-wave signals produced by cosmic strings in the Advanced LIGO and Virgo full O3 dataset. Search results are presented for gravitational waves produced by cosmic string loop features such as cusps, kinks, and, for the first time, kink-kink collisions. A template-based search for short-duration transient signals does not yield a detection. We also use the stochastic gravitational-wave background energy density upper limits derived from the O3 data to constrain the cosmic string tension Gμ as a function of the number of kinks, or the number of cusps, for two cosmic string loop distribution models. Additionally, we develop and test a third model that interpolates between these two models. Our results improve upon the previous LIGO-Virgo constraints on Gμ by 1 to 2 orders of magnitude depending on the model that is tested. In particular, for the one-loop distribution model, we set the most competitive constraints to date: Gμ≲4×10^{-15}. In the case of cosmic strings formed at the end of inflation in the context of grand unified theories, these results challenge simple inflationary models.

Constraints on Cosmic Strings Using Data from the Third Advanced LIGO-Virgo Observing Run

We search for gravitational-wave signals produced by cosmic strings in the Advanced LIGO and Virgo full O3 dataset. Search results are presented for gravitational waves produced by cosmic string loop features such as cusps, kinks, and, for the first time, kink-kink collisions. A template-based search for short-duration transient signals does not yield a detection. We also use the stochastic gravitational-wave background energy density upper limits derived from the O3 data to constrain the cosmic string tension Gμ as a function of the number of kinks, or the number of cusps, for two cosmic string loop distribution models. Additionally, we develop and test a third model that interpolates between these two models. Our results improve upon the previous LIGO-Virgo constraints on Gμ by 1 to 2 orders of magnitude depending on the model that is tested. In particular, for the one-loop distribution model, we set the most competitive constraints to date: Gμ≲4×10^{-15}. In the case of cosmic strings formed at the end of inflation in the context of grand unified theories, these results challenge simple inflationary models.

POS0754 DEVELOPMENT OF A RISK PREDICTION MODEL FOR VENOUS THROMBOEMBOLISM IN PATIENTS WITH SYSTEMIC LUPUS ERYTHEMATOSUS: THE SLE-VTE SCORE

Background:

Patients with systemic lupus erythematosus (SLE) have a substantially increased risk of venous thromboembolism (VTE). An individual VTE risk assessment is important to ensure that all patients are assessed and given adequate thromboprophylaxis.

Objectives:

We conducted this study to develop a risk score for VTE in patients with SLE.

Methods:

Patients with SLE who participated in the Chinese SLE Treatment and Research group were enrolled in this study. Patient baseline information and clinical laboratory indicators were obtained, and VTE events were recorded every 3-6 months during follow-up visits. The risk prediction model was created and internally validated using the bootstrap methods, and a scoring system was established (Figure 1).

Figure 1.

Flow chart of study design.

Results:

Out of 4,502 patients included in this study, 135 had a VTE event. After univariate analysis and Lasso regression, the following 11 variables were identified and included in the risk prediction model: male sex, age, BMI ≥25 kg/m2, hyperlipidemia, hypoalbuminemia, hsCRP>3 mg/L, renal involvement, nervous system involvement, anti-β2-glycoprotein I antibody positivity, lupus anticoagulant positivity, and no use of hydroxychloroquine. The AUC for the SLE-VTE score (Table 1) was 0.947 (95% CI, 0.9249-0.9694). The SLE-VTE score’s sensitivity and specificity with the optimal cutoff value of 13 were 0.919 and 0.881, respectively. The SLE-VTE score was superior to the GAPSS system in predicting the risk of VTE in patients with SLE (AUC= 0.947 vs. 0.680, P< 0.001; integrated discrimination improvement (IDI)= 0.6652, P< 0.001; net reclassification improvement (NRI)= 0.6652, P< 0.001).

Table 1.

Final multivariable analysis for venous thromboembolism risk in patients with SLE

β coefficientsOdds ratio* (95% CI)P-valuePoints in scoring systemMale0.6211.86(0.953-3.503)0.0612Age at study entry(≥50)0.8372.308(1.339-3.915)0.0023BMI02(kg/m20.7922.209(1.333-3.627)0.0023Hyperlipemia0.8382.313(1.246-4.166)0.0063Hypoalbuminemia2.1638.697(5.185-14.794)< 0.0017hsCRP>3 mg/L1.4524.272(2.618-6.968)< 0.0015Anti β2GPI1.0132.754(1.543-4.853)0.0013LA1.5594.752(2.799-8.072)< 0.0015Nervous system2.38210.832(6.163-18.998)< 0.0018Lupus nephritis0.8352.305(1.414-3.756)0.0013No use of hydroxychloroquine1.7715.876(3.722-9.401)< 0.0016

BMI: body mass index; hsCRP: Hypersensitive c-reactive protein; ACL: anticardiolipin, antiβ2GPI: anti-β2-glycoprotein I, LA: lupus anticoagulantm;

Values in bold are statistically significant at p <0.05.

Conclusion:

Various factors are related to the occurrence of VTE in patients with SLE. The proposed SLE-VTE risk score can accurately predict the risk of VTE and help identify SLE patients with a high risk of VTE who may benefit from thromboprophylaxis.

References:

[1]Ramirez GA, Efthymiou M, Isenberg DA, Cohen H. Under crossfire: thromboembolic risk in systemic lupus erythematosus. Rheumatology. 2018;58:940-952.

[2]Chung WS, Lin CL, Chang SN, Lu CC, Kao CH. Systemic lupus erythematosus increases the risks of deep vein thrombosis and pulmonary embolism: a nationwide cohort study. J Thromb Haemost. 2014;12:452-458.

[3]Liew NC, Alemany GV, Angchaisuksiri P, et al. Asian venous thromboembolism guidelines: updated recommendations for the prevention of venous thromboembolism. Int Angiol. 2017;36:1.

[4]Savino S, Giovanni S, Veronica M, Dario R, Khamashta MA, Laura BM. GAPSS: the Global Anti-Phospholipid Syndrome Score. Rheumatology. 2013:8.

[5]Konstantinides SV, Meyer G, Becattini C, et al. 2019 ESC Guidelines for the diagnosis and management of acute pulmonary embolism developed in collaboration with the European Respiratory Society (ERS). Eur Heart J. 2020;41:543-603.

[6]Moghadamyeghaneh Z, Hanna MH, Carmichael JC, Nguyen NT, Stamos MJ. A Nationwide Analysis of Postoperative Deep Vein Thrombosis and Pulmonary Embolism in Colon and Rectal Surgery. J Gastrointest Surg. 2014;18:2169-2177.

Disclosure of Interests:

None declared

A multi-orientation low-frequency rotational accelerometer

We present a low frequency rotational accelerometer coined ALFRA with a few nrad/Hz readout sensitivity above 20 mHz and 0.1 nrad/Hz above 50 mHz. The ALFRA is a beam-balance style rotation sensor, which pivots about a cross flexure designed to allow mounting with any orientation, the axis of the pivot determining which rotational component is measured. The high sensitivity is achieved through the use of a walk-off sensor readout used in a feedback loop with an electromagnetic coil to keep the beam dynamically locked. The ALFRA is relatively compact for a ground rotation sensor, measuring at 780 × 240 × 55 mm³.

Measurement of the Cosmic Ray Helium Energy Spectrum from 70 GeV to 80 TeV with the DAMPE Space Mission

The measurement of the energy spectrum of cosmic ray helium nuclei from 70 GeV to 80 TeV using 4.5 years of data recorded by the Dark Matter Particle Explorer (DAMPE) is reported in this work. A hardening of the spectrum is observed at an energy of about 1.3 TeV, similar to previous observations. In addition, a spectral softening at about 34 TeV is revealed for the first time with large statistics and well controlled systematic uncertainties, with an overall significance of 4.3σ. The DAMPE spectral measurements of both cosmic protons and helium nuclei suggest a particle charge dependent softening energy, although with current uncertainties a dependence on the number of nucleons cannot be ruled out.

OP0307 GUT MICROBIOTA AND ITS RELEVANCE TO PERIPHERAL LYMPHOCYTE SUBPOPULATION IN PATIENTS WITH SYSTEMIC LUPUS ERYTHEMATOSUS

Background:

Systemic lupus erythematosus (SLE) is an autoimmune disease with disturbance of lymphocyte subpopulations1. Growing experimental and clinical evidence suggests that chronic inflammatory response induced by gut microbiome critically contribute to the development of SLE2 3.

Objectives:

To investigate the characteristics of gut microbiome and the associations between flora and peripheral lymphocyte subpopulations in SLE patients.

Methods:

A total of 19 SLE patients who fulfilled the 2019 American college of Rheumatology (ACR) and European League Against Rheumatism (EULAR) classification criteria and 16 age- and sex- matched healthy controls (HC) were enrolled in this study. The peripheral T lymphocyte subsets of these participants were assessed by flow cytometry and the gut microbiota were investigated via 16s rRNA. Indicators of disease activity such as erythrocyte sedimentation rate (ESR), complement C3 and C4 were recorded at the same time. Mann-Whitney U test was applied to compare T lymphocyte subsets between SLE patients and HC. Spearman analysis was used for calculating correlation between T subsets and highly expressed differential flora as well as their correlation with disease activity indicators. All P-values reported herein were two-tailed and P-value<0.05 was taken as statistically significant.

Results:

SLE patients had higher proportions of Th17 cells (P=0.020) and γδT cells (P=0.018) but lower levels of Treg cells (P=0.001), Tfh cells (P=0.018) and Naïve CD4+T cells (P=0.004) (Figure 1a-e). The diversity and relative abundance of intestinal flora in patients with SLE were significantly different from those in HCs. Detailly, the α-diversity was decreased in SLE (P<0.05) (Figure 2a-c). Compared with HC, 11 species of flora were discovered to be distinctly different(P<0.05) (Figure 2d-e). Moreover, there was a significant positive correlation between Treg levels and Ruminococcus2 (P=0.042), Th17 and Megamonas (P=0.009), γδT and Streptococcus (P=0.004) as well as Megamonas (P=0.003), Tfh and Bacteroides (P=0.040). Whereas Th1 levels and Bifidobacterium were negatively correlated in these participants (P=0.005). As for clinical disease measures, there were negative correlations not only between ESR and Treg cells (P=0.031) but also C4 and the amount of Unclassified Ruminococcaceae (P=0.032).

Conclusion:

Abnormality of T cell subsets, especially the level of Naïve CD4+T, γδT, Tfh, Treg, and Th17 cells contributes to the occurrence and progression of SLE, which may be related to the disturbance of gut microbiota. Therefore it is necessary to attach importance to the alteration of gut microbiota to prevent the outbreak of inflammation and maybe they can be identified as biomarkers predicting disease activity.

References:

[1]Katsuyama T, Tsokos GC, Moulton VR. Aberrant T Cell Signaling and Subsets in Systemic Lupus Erythematosus. Front Immunol 2018;9:1088. doi: 10.3389/fimmu.2018.01088 [published Online First: 2018/06/06]

[2]López P, de Paz B, Rodríguez-Carrio J, et al. Th17 responses and natural IgM antibodies are related to gut microbiota composition in systemic lupus erythematosus patients. Sci Rep 2016;6:24072. doi: 10.1038/srep24072 [published Online First: 2016/04/06]

[3]Esmaeili SA, Mahmoudi M, Momtazi AA, et al. Tolerogenic probiotics: potential immunoregulators in Systemic Lupus Erythematosus. J Cell Physiol 2017;232(8):1994-2007. doi: 10.1002/jcp.25748 [published Online First: 2016/12/21]

Acknowledgements:

This project was supported by National Science Foundation of China (82001740), Open Fund from the Key Laboratory of Cellular Physiology (Shanxi Medical University) (KLCP2019) and Innovation Plan for Postgraduate Education in Shanxi Province (2020BY078).

Disclosure of Interests:

None declared.

[Optical correction principles of accommodative esotropia]

Accommodative esotropia is the most common type of esotropia in children. The patients often need to wear hyperopic glasses to correct eye positions and improve vision and binocular function. However, the course of accommodative esotropia is usually long, so it is necessary to monitor the refractive changes for a long time. Maintaining full hyperopic correction will interfere with the emmetropia development of the eyeball, and undercorrection of hyperopia will lead to the risk of esotropia decompensation. These often bring confusion when clinicians prescribe glasses. The benefits of accommodative esotropia with a high accommodation convergence/accommodation ratio from fitting bifocal lenses and the effect of prisms on residual esotropia have also been controversial topics in this field. In this article, we combine the research status and clinical practice to present some points of view for the peer reference. (Chin J Ophthalmol, 2021, 57: 331-335).

Clinical and genetic spectrum of a Chinese cohort with SCN4A gene mutations

Skeletal muscle sodium channelopathies due to SCN4A gene mutations have a broad clinical spectrum. However, each phenotype has been reported in few cases of Chinese origin. We present detailed phenotype and genotype data from a cohort of 40 cases with SCN4A gene mutations seen in neuromuscular diagnostic service in Huashan hospital, Fudan University. Cases were referred from 6 independent provinces from 2010 to 2018. A questionnaire covering demographics, precipitating factors, episodes of paralysis and myotonia was designed to collect the clinical information. Electrodiagnostic studies and muscle MRI were retrospectively analyzed. The clinical spectrum of patients included: 6 Hyperkalemic periodic paralysis (15%), 18 Hypokalemic periodic paralysis (45%), 7 sodium channel myotonia (17.5%), 4 paramyotonia congenita (10%) and 5 heterozygous asymptomatic mutation carriers (12.5%). Review of clinical information highlights a significant delay to diagnosis (median 15 years), reports of pain and myalgia in the majority of patients, male predominance, circadian rhythm and common precipitating factors. Electrodiagnostic studies revealed subclinical myotonic discharges and a positive long exercise test in asymptomatic carriers. Muscle MRI identified edema and fatty infiltration in gastrocnemius and soleus. A total of 13 reported and 2 novel SCN4A mutations were identified with most variants distributed in the transmembrane helix S4 to S6, with a hotspot mutation p.Arg675Gln accounting for 32.5% (13/40) of the cohort. Our study revealed a higher proportion of periodic paralysis in SCN4A-mutated patients compared with cohorts from England and the Netherlands. It also highlights the importance of electrodiagnostic studies in diagnosis and segregation studies.