Cardiac troponin I release in non-ischemic reversible myocardial injury from acute diphtheric myocarditis

Diphtheria-Associated Myocarditis: Clinical Profiles and Mortality Trends in a Tertiary Care Hospital in Pakistan

BACKGROUND

Corynebacterium diphtheriae infection, causing diphtheria, is a public health concern, particularly in developing nations like Pakistan. Despite immunization efforts, recent outbreaks since 2022 have emphasized the continuing threat. This study focuses on describing the clinical characteristics of children with diphtheria-induced myocarditis and exploring the association between early cardiac abnormalities, future fatality rates, and contributing factors.

METHODS

A one-year cross-sectional study was undertaken at Lady Reading Hospital MTI Peshawar, encompassing 73 pediatric patients diagnosed with diphtheria-associated myocarditis. Data, including demographic characteristics, cardiac enzymes, and serial ECG and echocardiography data, were gathered from the health management information system (HMIS). Institutional Ethical Committee approval was obtained, and informed consent was waived due to its retrospective nature.

RESULTS

Gender distribution within the study was balanced, with 35 males (47.9%) and 38 females (52.1%). ECG data revealed various prevalence rates: 27.4% for rhythm abnormalities, 20% for conduction abnormalities, 6.8% for ischemia alterations, and 20.5% for normal findings. Treatment measures included anti-diphtheria serum (ADS) in 87.7% and temporary pacemaker placement (TPM) in 13.7% of patients. Echo findings indicated a variety of cardiac dysfunctions: 53.4% with no dysfunction, 9.6% mild malfunction, 6.8% with moderate dysfunction, and 30.1% with severe dysfunction. The categorization of creatine kinase (CK), lactate dehydrogenase (LDH), and troponin I (Trop I) gave insights into the biochemical aspects.

CONCLUSION

This study gives a full insight into the clinical symptoms of diphtheria-induced myocarditis in children. The findings can help establish a foundation for ongoing study into potential gender-related trends in clinical outcomes, contributing to improved care and preventative methods.

Novel Clinical Monitoring Approaches for Reemergence of Diphtheria Myocarditis, Vietnam

Diphtheria is a life-threatening, vaccine-preventable disease caused by toxigenic Corynebacterium bacterial species that continues to cause substantial disease and death worldwide, particularly in vulnerable populations. Further outbreaks of vaccine-preventable diseases are forecast because of health service disruptions caused by the coronavirus disease pandemic. Diphtheria causes a spectrum of clinical disease, ranging from cutaneous forms to severe respiratory infections with systemic complications, including cardiac and neurologic. In this synopsis, we describe a case of oropharyngeal diphtheria in a 7-year-old boy in Vietnam who experienced severe myocarditis complications. We also review the cardiac complications of diphtheria and discuss how noninvasive bedside imaging technologies to monitor myocardial function and hemodynamic parameters can help improve the management of this neglected infectious disease.

Role of Cardiac Macrophages on Cardiac Inflammation, Fibrosis and Tissue Repair

The immune system plays a pivotal role in the initiation, development and resolution of inflammation following insult or damage to organs. The heart is a vital organ which supplies nutrients and oxygen to all parts of the body. Heart failure (HF) has been conventionally described as a disease associated with cardiac tissue damage caused by systemic inflammation, arrhythmia and conduction defects. Cardiac inflammation and subsequent tissue damage is orchestrated by the infiltration and activation of various immune cells including neutrophils, monocytes, macrophages, eosinophils, mast cells, natural killer cells, and T and B cells into the myocardium. After tissue injury, monocytes and tissue-resident macrophages undergo marked phenotypic and functional changes, and function as key regulators of tissue repair, regeneration and fibrosis. Disturbance in resident macrophage functions such as uncontrolled production of inflammatory cytokines, growth factors and inefficient generation of an anti-inflammatory response or unsuccessful communication between macrophages and epithelial and endothelial cells and fibroblasts can lead to aberrant repair, persistent injury, and HF. Therefore, in this review, we discuss the role of cardiac macrophages on cardiac inflammation, tissue repair, regeneration and fibrosis.

Diphtheria

Diphtheria is a potentially fatal infection mostly caused by toxigenic Corynebacterium diphtheriae strains and occasionally by toxigenic C. ulcerans and C. pseudotuberculosis strains. Diphtheria is generally an acute respiratory infection, characterized by the formation of a pseudomembrane in the throat, but cutaneous infections are possible. Systemic effects, such as myocarditis and neuropathy, which are associated with increased fatality risk, are due to diphtheria toxin, an exotoxin produced by the pathogen that inhibits protein synthesis and causes cell death. Clinical diagnosis is confirmed by the isolation and identification of the causative Corynebacterium spp., usually by bacterial culture followed by enzymatic and toxin detection tests. Diphtheria can be treated with the timely administration of diphtheria antitoxin and antimicrobial therapy. Although effective vaccines are available, this disease has the potential to re-emerge in countries where the recommended vaccination programmes are not sustained, and increasing proportions of adults are becoming susceptible to diphtheria. Thousands of diphtheria cases are still reported annually from several countries in Asia and Africa, along with many outbreaks. Changes in the epidemiology of diphtheria have been reported worldwide. The prevalence of toxigenic Corynebacterium spp. highlights the need for proper clinical and epidemiological investigations to quickly identify and treat affected individuals, along with public health measures to prevent and contain the spread of this disease.

Cardiac complications in diphtheria and predictors of outcomes

OBJECTIVE

To study the cardiac complications in diphtheria patients and to study the predictors of outcomes.

STUDY DESIGN

Single centre prospective analysis of cardiac complications in diphtheria patients.

RESULTS

In this study, there were 60 patients diagnosed with diphtheria with ECG changes. The ECG changes seen were sinus tachycardia (68.3%), T wave inversion (20%), ST segment depression (13.3%), right bundle branch block (5%), multiple atrial ectopics (3.3%). The case fatality rate in our study was 25% (15 patients). High CPK-MB, myoglobulin and cardiac troponin levels were associated with cardiac mortality. In our study, cardiac troponin T had the highest sensitivity (80%) and CK-MB had the highest specificity (95.56%).

CONCLUSION

Cardiac involvement is a common complication of infection with C. diphtheria and is associated with high mortality. As diphtheria can be prevented by adequate vaccination, efforts should be maximized for high vaccine coverage with booster doses.

Myocardial biomarkers and delayed enhanced cardiac magnetic resonance relationship in clinically suspected myocarditis and insight on clinical outcome

AIMS

The relationship of cardiac magnetic resonance (CMR) late gadolinium enhancement (LGE) with myocardial biomarkers and markers of inflammation in acute viral myocarditis is not clearly defined. We assessed the relationship of LGE with myocardial and inflammatory biomarkers measured during the acute phase of myocarditis and their predictive value on clinical outcome.

METHODS

Patients with first clinical episode of acute viral myocarditis and complete CMR study, including cine and LGE images, were included. The peak values of troponin I, creatine kinase, C-reactive protein value at admission and LGE extent were reported for each case. A 29-month clinical follow-up was performed, and cardiac symptoms and adverse cardiac events (all-cause death, heart transplant, hospitalization for heart failure) were reported.

RESULTS

Forty-one patients (39 ± 15 years and 78% men) were included. Median LGE extent was 13% [interquartile range (IQR) (9%, 19%)] of left-ventricular mass and mean left-ventricular ejection fraction was 56 ± 11%. There was a significant correlation between peak troponin I and LGE extent (r = 0.51, P < 0.001), and between peak creatine kinase and LGE extent (r = 0.66, P < 0.001). There was no correlation between C-reactive protein at admission and LGE extent (r = 0.27, P = 0.09). At follow-up, eight (20%) patients had an adverse clinical event. LGE extent was significantly associated with a worse New York Heart Association status at follow-up [odds ratio (OR) 1.21, 95% confidence interval (CI) 1.07, 1.37, P = 0.002]. After adjustment for left-ventricular ejection fraction, age and clinical presentation category, LGE extent remained an independent predictor of cardiovascular events (hazard ratio 1.42; 95% CI 1.05, 1.95, P = 0.027).

CONCLUSIONS

LGE extent on CMR studies is significantly correlated to biomarkers of myocardial injury in patients with acute viral myocarditis, and is a significant independent predictor of adverse cardiovascular outcome.

Markedly Elevated Cardiac Bio-Markers at Presentation With Normal Ventricular Function: A Novel Clinical Subset of Myocarditis Manifestation

We present a case of a 19-year-old woman with myocarditis who had significantly elevated cardiac markers at presentation even before any myocardial damage ensued. The patient had complicated clinical course with ventricular arrhythmia and cardiac arrest requiring resuscitation but eventually recovered completely. Though there is limited information available regarding such cases, the significantly elevated initial cardiac markers in the absence of left ventricular decompensation may probably represent a clinical subset of myocarditis and may portend an impending complicated clinical course. Further systematic research is required to define the clinical phenotype and elucidate underlying mechanisms.

Effect of Time Delay on the Diagnostic Use of Contrast Echocardiography in Patients Presenting to the Emergency Department with Chest Pain and no S-T Segment Elevation

BACKGROUND

The purpose of this study was to assess the effect of time delay on the diagnostic and prognostic use of contrast echocardiography (CE) in patients presenting to the emergency department (ED) with chest pain (CP) and no S-T segment elevation.

METHODS

Patients (n = 957, 498 men) presenting to the ED within 12 hours of suggested cardiac CP underwent CE. Regional function (RF) and myocardial perfusion were interpreted separately by expert readers blinded to all other clinical data. Primary (acute myocardial infarction and total mortality) and secondary (unstable angina and revascularization) events within 24 hours of enrollment were determined.

RESULTS

Patients were divided into 4 quartiles based on the time interval between their last episode of CP and CE. Patients in quartile I had CE during CP (time delay of 0 minutes). The time delay in quartiles II, III, and IV were 54 +/- 45, 213+/-54, and 556 +/- 184 minutes, respectively (P < .001). The incidence of events was similar among the 4 quartiles. In each quartile, patients with normal RF had the lowest incidence of events, whereas those with both abnormal RF and myocardial perfusion had the highest incidence of events. Patients with abnormal RF but normal myocardial perfusion had an intermediate event rate.

CONCLUSIONS

In patients presenting to the ED within 12 hours of CP, the timing of CE does not influence its ability to predict events that occur 24 hours later. These findings have important implications in the performance of CE in the ED.

Cardiac troponin I release in non-ischemic reversible myocardial injury from parvovirus B19 myocarditis

Cardiac troponin I is released from myocytes in both reversible and irreversible myocardial injury. The changes in myocyte membrane permeability resulting from the injury could be enough for the release of cardiac troponins from the free cytosolic pool of myocytes without structural damage. We report a case of parvovirus B19 myocarditis in a 26-year-old male who developed regional wall motion abnormalities and severe left ventricular systolic dysfunction with elevated serum levels of cardiac troponin I (peak=11.7 ng/ml). Diagnosis of parvovirus myocarditis was confirmed by presence of high titers of parvovirus B19 IgG and identification of parvovirus B19 DNA by polymerase chain reaction. Within a few days of supportive treatment, the regional wall motion abnormalities resolved, the cardiac function recovered, and the elevation in serum cardiac troponin I subsided. This case further denotes the possibility of release of cardiac troponin I in non-ischemic, reversible myocardial injury.