Myocarditis represents a diverse group of inflammatory diseases affecting the heart muscle, with both infectious and non-infectious etiologies. Among the non-infectious causes, drug-induced hypersensitivity reactions are rare but serious. Isoniazid, a cornerstone in tuberculosis treatment, is known for its hepatotoxicity but has rarely been documented to cause hypersensitivity myocarditis.

We present a case of a 15-year-old girl from Eastern Turkmenistan who was admitted to our emergency department with altered consciousness and seizure activity. She was diagnosed with status epilepticus and treated accordingly. The patient, with no prior medical history, was found to have hypotensive shock and myocarditis upon further examination. A detailed history revealed she had ingested 45 tablets of expired isoniazid in a suicide attempt. She was treated with pyridoxine and supportive therapies, resulting in a gradual recovery.

This case underscores the critical need to consider drug-induced hypersensitivity myocarditis in the differential diagnosis of myocarditis, especially in patients with recent medication use. Prompt recognition and appropriate treatment with pyridoxine, steroid, and supportive cardiac care can be lifesaving. This case also highlights the importance of awareness regarding the potential cardiotoxic effects of isoniazid overdose.

Clozapine-induced inflammation, such as myocarditis and pneumonia, can occur during initial titration and can be fatal. Fever is often the first sign of severe inflammation, and early detection and prevention are essential. Few studies have investigated the effects of clozapine titration speed and concomitant medication use on the risk of clozapine-induced inflammation.

We evaluated the risk factors for clozapine-associated fever, including titration speed, concomitant medication use, gender and obesity, and their impact on the risk of fever and the fever onset date.

We conducted a case-control study. The medical records of 539 Japanese participants with treatment-resistant schizophrenia at 21 hospitals in Japan who received clozapine for the first time between 2010 and 2022 were retrospectively investigated. Of these, 512 individuals were included in the analysis. Individuals were divided into three groups according to the titration rate recommended by international guidelines for East Asians: the faster titration group, the slower titration group and the ultra-slower titration group. The use of concomitant medications (such as antipsychotics, mood stabilisers, hypnotics and anxiolytics) at clozapine initiation was comprehensively investigated. Logistic regression analysis was performed to identify the explanatory variables for the risk of a fever of 37.5°C or higher lasting at least 2 days.

Fever risk significantly increased with faster titration, male gender and concomitant use of valproic acid or quetiapine. No increased fever risk was detected with the use of other concomitant drugs, such as olanzapine, lithium or orexin receptor antagonists. Fever onset occurred significantly earlier with faster titration. Multivariate analysis identified obesity as being a factor that accelerated fever onset.

A faster titration speed and concomitant treatment with valproic acid and quetiapine at clozapine initiation increased the risk of clozapine-associated fever. Clinicians should titrate clozapine with caution and consider both the titration speed and concomitant medications.

Multisystem inflammatory syndrome in children is an inflammatory syndrome related to severe acute respiratory syndrome coronavirus 2 with a high risk of cardiovascular complications (vasoplegia, cardiac shock). We investigated the cardiac outcomes in multisystem inflammatory syndrome in children, focusing on the identification of predictors for late cardiac function impairment.

Clinical characteristics, conventional echocardiography (left ventricle ejection fraction, fractional shortening), 4-chamber left ventricular global longitudinal strain, and cardiac MRI of multisystem inflammatory syndrome in children patients (n = 48) were collected during admission, 6 weeks, 6 months, >12–≤18 months, and >18–≤24 months post-onset. Paired over-time patterns were assessed and multivariable regression analyses were performed to identify predictors for late global longitudinal strain impairment.

In total, 81.3% of patients had acute cardiac dysfunction (left ventricle ejection fraction <50% and/or fractional shortening <28%). The left ventricle ejection fraction and fractional shortening reached a plateau level ≤6 weeks, while the global longitudinal strain continued to decrease in the first 6 months post-onset (median –17.3%, P < 0.001 [versus acute]). At 6 months, 35.7% of the patients still had an abnormal global longitudinal strain, which persisted in 5/9 patients that underwent echocardiography >12–≤18 months post-onset and in 3/3 patients >18–≤24 months post-onset. In a multivariable analysis, soluble troponin T (>62.0 ng/L [median]) was associated with reduced global longitudinal strain at 6 months. Our cardiac MRI findings indicated acute myocardial involvement (increased T1/T2 value) in 77.8% (7/9), which recovered quickly without signs of fibrosis on convalescent cardiac MRIs.

Late global longitudinal strain impairment is seen in some multisystem inflammatory syndrome in children patients up to one-year post-onset. Careful cardiac follow-up in patients with elevated troponin in the acute phase and patients with persistent abnormal global longitudinal strain is warranted until resolution of the global longitudinal strain since the long-term implications of such abnormalities are still unclear.

In pediatric multisystem inflammatory syndrome and isolated viral myocarditis/myopericarditis, autonomic nervous system function can be evaluated by a non-invasive method called heart rate variability. This study aims to evaluate heart rate variability in these two groups by comparing them with each other. This is the first study assessing these values in these two groups of patients.

Patients who are diagnosed with multisystem inflammatory syndrome in children and isolated viral myocarditis/myopericarditis at a university hospital from September 2021 to February 2023 are screened by electrocardiography, echocardiography, and 24-hour Holter monitoring. A healthy control group, compatible in age and gender with the patient groups, was selected from healthy subjects that applied to the hospital for palpitation, murmur, and/or chest pain. Heart rate variability parameters and related laboratory markers were analyzed and compared among the three groups.

There were 30 patients with multisystem inflammatory syndrome in children, 43 patients with isolated viral myocarditis/myopericarditis, and 109 participants in the healthy control group. Statistically significant differences were found in most of the heart rate variability parameters: standard deviation of normal to normal intervals (SDNN), the mean of the 5- minute RR interval standard deviations (SDNNİ), the standard deviation of 5-minute R wave to R wave(RR) interval means (SDANN), the root mean square of successive RR interval differences (RMSSD), and the percentage of the beats with a consecutive RR interval difference of more than 50 ms (pNN50%), very low frequency, high frequency, low frequency, triangular index, and low frequency/high-frequency ratio. Multisystem inflammatory syndrome in children patients had impaired and declined heart rate variability values compared to the other two groups. In patients with myocarditis/myopericarditis, we couldn’t find a significant difference in these parameters with the control group.

Heart rate variability can be used as an important non-invasive autonomic function parameter in determining prognosis and treatment plans, especially in patients diagnosed with multisystem inflammatory syndrome in children. This impairment of autonomic activity could be more prominent in patients with decreased left ventricular systolic functions.

Public interest in the severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) vaccines has been rising with regard to associated myocarditis. Thus, the objective of our study was to assess trends in public interest in myocarditis during the course of the pandemic and the SARS-CoV-2 vaccine rollout in the United States.

We conducted a longitudinal assessment of public interest in myocarditis, and its association with actual coronavirus disease 2019 (COVID-19) -related myocarditis during the first wave of the pandemic and SARS-CoV-2 vaccine-related myocarditis following vaccine rollout. To complete this objective, we used data from 3 sources: a report from the Morbidity and Mortality Weekly Report, the Vaccine Adverse Event Reporting database, and from Google Trends.

Results show that Relative Search Interest (RSI) was low before and during the initial phase of the pandemic and peaked in April 2021, during the initial vaccine push. The ratio of myocarditis related to the SARS-CoV-2 vaccines was considerably lower than the ratio of myocarditis from natural infection.

Search interest in myocarditis was low until SARS-CoV-2 vaccines were rolled out, in which media coverage intensely focused on a relatively small number of cases. This study highlights both the benefits of COVID-19 vaccine uptake and the impact of the media on public interest

When cardiac muscle damage occurs, cardiac troponins are released to blood and their detection is used as a marker in clinical setting. The prognostic value of the quantitative levels of blood troponin I in cases of myocarditis and myopericarditis is unclear. The aim of this study was to analyse whether troponin quantitative blood levels can be correlated with the course of hospitalisation and prognosis.

Retrospective data was collected from all consecutive patients aged ≤30 hospitalised with a diagnosis of acute myocarditis or acute myopericarditis in our health Care Campus between the years 2010–2016.

Ninety-three patients with myocarditis and myopericarditis were identified. Higher peak troponin levels correlated with longer hospitalisation times in the cardiac or paediatric wards (p = 0.03, Pearson correlation: r −0.23), and median troponin level at admission correlated with longer overall hospitalisation (p = 0.026, Pearson correlation: r = 0.23). Patients admitted to ICU, received oral cardiac supportive therapy or that were discharged with cardiac drugs had higher median troponin compared to patients who were not but this was not statistically significant. A small group of patients that needed intravenous cardiac support had significantly lower median peak troponin levels (n = 4, 0.375ng/ml, p = 0.048). Only two patients needed extracorporeal membrane oxygenation support, and one died. The small number of patients precludes statistical analysis.

Higher troponin levels correlated significantly with longer hospitalisation, lower troponin values correlated with intravenous cardiac support, while other variables related to the severity of disease could not be significantly related to higher troponin levels.

While most children with multisystem inflammatory syndrome in children have rapid recovery of cardiac dysfunction, little is known about the long-term outcomes regarding exercise capacity. We aimed to compare the exercise capacity among patients with multisystem inflammatory syndrome in children versus viral/idiopathic myocarditis at 3–6 months after initial diagnosis.

We performed a retrospective cohort study among patients with multisystem inflammatory syndrome in children in June 2020 to May 2021 and patients with viral/idiopathic myocarditis in August 2014 to January 2020. Data from cardiopulmonary exercise test as well as echocardiographic and laboratory data were obtained. Inclusion criteria included diagnosis of multisystem inflammatory syndrome in children or viral/idiopathic myocarditis, exercise test performed within 3–6 months of hospital discharge, and maximal effort on cardiopulmonary exercise test as determined by respiratory exchange ratio >1.10.

Thirty-one patients with multisystem inflammatory syndrome in children and 25 with viral/idiopathic myocarditis were included. The mean percent predicted peak VO2 was 90.84% for multisystem inflammatory syndrome in children patients and 91.08% for those with viral/idiopathic myocarditis (p-value 0.955). There were no statistically significant differences between the groups with regard to percent predicted maximal heart rate, metabolic equivalents, percent predicted peak VO2, percent predicted anerobic threshold, or percent predicted O2 pulse. There was a statistically significant correlation between lowest ejection fraction during hospitalisation and peak VO2 among viral/idiopathic myocarditis patients (r: 0.62, p-value 0.01) but not multisystem inflammatory syndrome in children patients (r: 0.1, p-value 0.6).

Patients with multisystem inflammatory syndrome in children and viral myocarditis appear to, on average, have normal exercise capacity around 3–6 months following hospital discharge. For patients with viral/idiopathic myocarditis, those with worse ejection fraction during hospitalisation had lower peak VO2 on cardiopulmonary exercise test.