Usefulness of Heart-Type Fatty Acid-Binding Protein and Myocardial Performance Index for Early Detection of 5-Fluorouracil Cardiotoxicity

Management of Fluoropyrimidine-Induced Cardiac Adverse Outcomes Following Cancer Treatment

Advancements in cancer treatments have improved survival rates but have also led to increased cardiotoxicities, which can cause adverse cardiovascular events or worsen pre-existing conditions. Herein, cardiotoxicity is a severe adverse effect of 5-fluorouracil (5-FU) therapy in cancer patients, with reported incidence rates ranging from 1 to 20%. Some studies have also suggested subclinical effects and there are reports which have documented instances of cardiac arrest or sudden death during 5-FU treatment, highlighting the importance of timely management of cardiovascular symptoms. However, despite being treated with conventional medical approaches for this cardiotoxicity, a subset of patients has demonstrated suboptimal or insufficient responses. The frequent use of 5-FU in chemotherapy and its association with significant morbidity and mortality indicates the need for a greater understanding of 5-FU-associated cardiotoxicity. It is essential to reduce the adverse effects of anti-tumor medications while preserving their efficacy, which can be achieved through drugs that mitigate toxicity associated with these drugs. Underpinning cardiotoxicity associated with 5-FU therapy also has the potential to offer valuable guidance in pinpointing pharmacological approaches that can be employed to prevent or ameliorate these effects. The present study provides an overview of management strategies for cardiac events induced by fluoropyrimidine-based cancer treatments. The review encompasses the underlying molecular and cellular mechanisms of cardiotoxicity, associated risk factors, and diagnostic methods. Additionally, we provide information on several available treatments and drug choices for angina resulting from 5-FU exposure, including nicorandil, ranolazine, trimetazidine, ivabradine, and sacubitril-valsartan, which have demonstrated potential in mitigating or protecting against chemotherapy-induced adverse cardiac effects.

Redefining the Incidence and Profile of Fluoropyrimidine-Associated Cardiotoxicity in Cancer Patients: A Systematic Review and Meta-Analysis

Aim: The cardiac toxicity that occurs during administration of anti-tumor agents has attracted increasing concern. Fluoropyrimidines have been used for more than half a century, but their cardiotoxicity has not been well clarified. In this study, we aimed to assess the incidence and profile of fluoropyrimidine-associated cardiotoxicity (FAC) comprehensively based on literature data. Methods: A systematic literature search was performed using PubMed, Embase, Medline, Web of Science, and Cochrane library databases and clinical trials on studies investigating FAC. The main outcome was a pooled incidence of FAC, and the secondary outcome was specific treatment-related cardiac AEs. Random or fixed effects modeling was used for pooled meta-analyses according to the heterogeneity assessment. PROSPERO registration number: (CRD42021282155). Results: A total of 211 studies involving 63,186 patients were included, covering 31 countries or regions in the world. The pooled incidence of FAC, by meta-analytic, was 5.04% for all grades and 1.5% for grade 3 or higher. A total of 0.29% of patients died due to severe cardiotoxicities. More than 38 cardiac AEs were identified, with cardiac ischemia (2.24%) and arrhythmia (1.85%) being the most frequent. We further performed the subgroup analyses and meta-regression to explore the source of heterogeneity, and compare the cardiotoxicity among different study-level characteristics, finding that the incidence of FAC varied significantly among different publication decades, country/regions, and genders. Patients with esophagus cancer had the highest risk of FAC (10.53%), while breast cancer patients had the lowest (3.66%). The treatment attribute, regimen, and dosage were significantly related to FAC. When compared with chemotherapeutic drugs or targeted agents, such a risk was remarkably increased (χ2 = 10.15, p < 0.01; χ2 = 10.77, p < 0.01). The continuous 5-FU infusion for 3–5 consecutive days with a high dosage produced the highest FAC incidence (7.3%) compared with other low-dose administration patterns. Conclusions: Our study provides comprehensive global data on the incidence and profile of FAC. Different cancer types and treatment appear to have varying cardiotoxicities. Combination therapy, high cumulative dose, addition of anthracyclines, and pre-existing heart disease potentially increase the risk of FAC.

Treatment-Related Coronary Disorders of Fluoropyrimidine Administration: A Systematic Review and Meta-Analysis

Background: Coronary disorders are recognized as the most common manifestation of fluoropyrimidine-related cardiotoxicity in clinical practice. However, there are limited and conflicting data on the incidence and profiles of fluoropyrimidine-related coronary disorders. In this meta-analysis, we aimed to systematically assess the incidence of all-grade and grade 3 or higher fluoropyrimidine-related coronary disorders, and further explore the factors that influence its occurrence.

Methods: Studies reporting the fluoropyrimidine-related coronary disorders were retrieved from a systematic search of English literature in the PubMed, Web of Science, Medline, and Cochrane database from 1 Jan 2001, to 1 Jan 2022. The NIH assessment tool was used to evaluate the quality of each study. The data of basic study characteristics, treatment details, and results of coronary toxicities were extracted. According to the results of the heterogeneity test (I² and p-value statistic), a random-effect model or fixed-effect model was selected for the pooled analysis of the incidence of adverse coronary events. Subgroup analysis was conducted to further explore the risks influencing the occurrence of fluoropyrimidine-related coronary disorders. The stability and publication bias of our results were evaluated by sensitivity analysis and Egger test, respectively.

Results: A total of 63 studies were finally included in our pooled analysis, involving 25,577 patients. The pooled cumulative incidence of all-grade and grade 3 or higher coronary disorders was 2.75% (95% CI 1.89%–3.76%) and 1.00% (95% CI 0.62%–1.47%), respectively. The coronary disorders were most reported as myocardial ischemia (1.28%, 95% CI 0.42%–2.49%) and angina/chest pain (1.1%, 95% CI 0.54%–1.81%). Subgroup analysis revealed that studies in the female-only population seemed to have a lower incidence of fluoropyrimidine-related coronary disorders. The occurrence of adverse coronary events varied among different tumor types. Patients with esophageal cancer have the highest coronary toxicity (6.32%), while those with breast cancer have a relatively lower incidence (0.5%). Coronary disorders induced by 5-FU monotherapy are more frequent than that induced by capecitabine (3.31% vs. 1.21%, p < 0.01). Fluoropyrimidine combination therapy, whether combined with other chemotherapy drugs, targeted therapy drugs, or radiotherapy, significantly increased the incidence of coronary complications (p < 0.01).

Conclusion: This meta-analysis has defined the incidence of fluoropyrimidine-related coronary disorders and depicted its epidemiological profiles for the first time, which may provide a reference for clinical practice in cancer management.

Cardioprotective effects of bosentan in 5-fluorouracil-induced cardiotoxicity

5-fluorouracil (5-FU) is a widely used chemotherapeutic agent but cardiotoxicity challenges its clinical usefulness. Thus, searching for more cardioprotective drugs is highly required to prevent the accompanied cardiac hazards. Up to date, the different mechanisms involved in 5-FU cardiotoxicity are still unclear and there is no evaluation of bosentan's role in controlling these cardiac complications. This forced us to deeply study and evaluate the possible cardiopreserving properties of bosentan and different mechanisms involved in mediating it. 32 Wistar albino rats were included in our experiment and induction of cardiotoxicity was performed via administration of 5-FU (150 mg/kg) on 5th day of the experiment by intraperitoneal (i.p.) injection with or without co-administration of bosentan (50 mg/kg/day) orally for 7days. Our data revealed that 5-FU could induce cardiotoxicity which was detected as significant increases of troponin I, lactate dehydrogenase (LDH), creatine kinase- MB (CK-MB), endothelin receptors, malondialdehyde (MDA), toll like receptor4 (TLR4), myeloid differentiation primary response 88 (MyD88), nuclear factor kappa B (NFκB), and caspase 3 levels. However, there is marked decrease in endothelial nitric oxide synthase (eNOS), reduced glutathione (GSH) and total antioxidant capacity (TAC). In addition, the histopathological examination showed severe toxic features of cardiac injury. Interestingly, co-administration of bosentan could ameliorate 5-FU-induced cardiotoxicity via improving the detected biochemical and histopathological changes besides modulation of TLR4/MyD88/NFκB signaling pathway, eNOS, and endothelin receptors. Bosentan had a significant cardioprotective effect against 5-FU induced cardiac damage. This effect may be attributed to its ability to inhibit endothelin receptors, stimulates eNOS, anti-oxidant, anti-inflammatory, anti-apoptotic properties with modulation of TLR4/MyD88/NFκB signaling pathway.

Heart Failure in Breast Cancer Survivors: Focus on Early Detection and Novel Biomarkers

PURPOSE OF REVIEW

Breast cancer survival rate has greatly improved in the last two decades due to the emergence of next-generation anti-cancer agents. However, cardiotoxicity remains a significant adverse effect arising from traditional and emerging chemotherapies as well as targeted therapies for breast cancer patients. In this review, we will discuss cardiotoxicities of both traditional and emerging therapies for breast cancer. We will discuss current practices to detect cardiotoxicity of these therapies with the focus on new and emerging biomarkers. We will then focus on 'omics approaches, especially the use of epigenetics to discover novel biomarkers and therapeutics to mitigate cardiotoxicity.

RECENT FINDINGS

Significant cardiotoxicities of conventional chemotherapies remain and new and unpredictable new forms of cardiac and/or vascular toxicity emerge with the surge in novel and targeted therapies. Yet, there is no clear guidance on detection of cardiotoxicity, except for significant left ventricular systolic dysfunction, and even then, there is no uniform definition of what constitutes cardiotoxicity. The gold standard for detection of cardiotoxicity involves a serial echocardiography in conjunction with blood-based biomarkers to detect early subclinical cardiac dysfunction. However, the ability of these tests to detect early disease remains limited and not all forms of toxicity are detectable with these modalities. There is an unprecedented need to discover novel biomarkers that are sensitive and specific for early detection of subclinical cardiotoxicity. In that space, novel echocardiographic techniques, such as strain, are becoming more common-place and new biomarkers, discovered by epigenetic approaches, seem to become promising alternatives or adjuncts to conventional non-specific cardiac biomarkers.

Cardiotoxicity of Fluoropyrimidines: Epidemiology, Mechanisms, Diagnosis, and Management

Cancer is a growing public health problem; it is responsible annually for millions of deaths worldwide. Fluoropyrimidines are highly effective and commonly prescribed anti-neoplastic drugs used in a wide range of chemotherapy regimens against several types of malignancies. 5-fluorouracil and its prodrugs affect neoplastic cells in multiple ways by impairing their proliferation, principally through the inhibition of thymidylate synthase. Fluoropyrimidine-induced cardiotoxicity was described more than 50 years ago, but many details such as incidence, mechanisms, and treatment are unclear and remain disputed. Severe cardiotoxicity is not only life-threatening, but also leads to withdrawal from an optimal chemotherapy regimen and decreases survival rate. Differences in the frequency of cardiotoxicity are explained by different chemotherapy schedules, doses, criteria, and populations. Proposed pathophysiological mechanisms include coronary vasospasm, endothelial damage, oxidative stress, Krebs cycle disturbances, and toxic metabolites. Such varied pathophysiology of the cardiotoxicity phenomenon makes prevention and treatment more difficult. Cardiovascular disturbances, including chest pain, arrhythmias, and myocardial infarction, are among the most common side effects of this class of anti-neoplastic medication. This study aims to summarize the available data on fluoropyrimidine cardiotoxicity with respect to symptoms, incidence, metabolism, pathophysiological mechanism, diagnosis, management, and resistance.

Severe Cardiac Toxicity Induced by Cancer Therapies Requiring Intensive Care Unit Admission

A steadying increase of cancer survivors has been observed as a consequence of more effective therapies. However, chemotherapy regimens are often associated with significant toxicity, and cardiac damage emerges as a prominent clinical issue. Many mechanisms sustain chemotherapy-induced cardiac toxicity: direct myocyte damage, arrhythmia induction, coronary vasospasm, and accelerated atherosclerosis. Anthracyclines are the most studied cardiotoxic drugs and represent a clinical model for cardiac damage induced by chemotherapy. In patients suffering from advanced heart failure (HF) because of chemotherapy-related cardiomyopathy, when refractory to optimal medical therapy, mechanical circulatory support or heart transplantation represents an effective treatment. Here, the main mechanisms of cardiac toxicity induced by cancer therapies are analyzed, with a focus on patients requiring intensive care unit (ICU) admission during the course of the disease because of acute cardiac toxicity, takotsubo syndrome, and acute-on-chronic HF in patients suffering from chemotherapy-induced cardiomyopathy. In a subset of patients, cardiac toxicity can be acute and life-threatening, leading to overt cardiogenic shock. The management of critically ill cancer patients poses a unique challenge and requires a multidisciplinary approach. Moreover, no etiologic therapy is available, and only supportive measures can be implemented.

Cardiotoxicity Associated with Chemotherapy Used in Gastrointestinal Tumours

Cardiotoxicity is a well-recognised side effect of cancer-related therapies with a great impact on outcomes and quality of life in the cancer survivor population. The pathogenesis of chemotherapy-induced cardiotoxicity in patients with gastrointestinal cancers involves various molecular mechanisms, and the combined use of various chemotherapies augments the risk of each drug used alone. In terms of cardiotoxicity diagnosis, novel biomarkers, such as troponins, brain natriuretic peptide (BNP), myeloperoxidases and miRNAs have been recently assessed. Echocardiography is a noninvasive imaging method of choice for the primary assessment of chemotherapy-treated patients to generally evaluate the cardiovascular impact of these drugs. Novel echocardiography techniques, like three-dimensional and stress echocardiography, will improve diagnosis efficacy. Cardiac magnetic resonance (CMR) can evaluate cardiac morphology, function and wall structure. Corroborated data have shown the importance of CMR in the early evaluation of patients with gastrointestinal cancers, treated with anticancer drugs, but further studies are required to improve risk stratification in these patients. In this article, we review some important aspects concerning the cardiotoxicity of antineoplastic drugs used in gastrointestinal cancers. We also discuss the mechanism of cardiotoxicity, the role of biomarkers and the imaging methods used in its detection.

Myocardial Ischemia Induced by 5-Fluorouracil: A Prospective Electrocardiographic and Cardiac Biomarker Study

BACKGROUND

Cardiotoxicity induced by 5-fluorouracil (5-FU) is well known but poorly understood. In this study, we undertook ECG recording (Holter) and analyses of the biomarkers troponin and copeptin in patients receiving 5-FU to increase our understanding of the cardiotoxicity.

SUBJECTS, MATERIALS, AND METHODS

Patients with colorectal or anal cancer that received first-time treatment with 5-FU-based chemotherapy were prospectively included. Holter recording, clinical evaluation, 12-lead electrocardiogram, and assessment of plasma concentrations of troponin I and copeptin were performed before (control) and during 5-FU treatment (intervention).

RESULTS

A total of 108 patients were included, 82 with colorectal and 26 with anal cancer. The proportion of patients with myocardial ischemia on Holter recording was significantly higher during the first 5-FU infusion (14.1%) than before (3.7%; p = .001). The ischemic burden per day (p = .001), the number of ST depression episodes per day (p = .003), and the total duration of ischemic episodes per day (p = .003) were higher during the first 5-FU infusion than before, as was plasma copeptin (p < .001), whereas plasma troponin I was similar (p > 0.999). Six patients (5.6%) developed acute coronary syndromes and two (1.8%) developed symptomatic arrhythmias during 5-FU treatment.

CONCLUSION

5-FU infusion is associated with an increase in the number of patients with myocardial ischemia on Holter recording. According to biomarker analyses, 5-FU is associated with an increase in copeptin, but rarely with increases in cardiac troponin I. However, 5%-6% of the patients developed acute coronary syndromes during treatment with 5-FU.

IMPLICATIONS FOR PRACTICE

Symptomatic 5-fluorouracil (5-FU) cardiotoxicity occurs in 0.6%-19% of patients treated with this drug, but a small electrocardiographic (Holter) study has revealed silent myocardial ischemia in asymptomatic patients, suggesting a more prevalent subclinical cardiac influence. This study demonstrated a significant increase in the number of patients with myocardial ischemia on Holter recording during 5-FU treatment and an increase in ischemic burden. Cardiac biomarker analyses suggested that 5-FU infusion results in endogenous stress (increased copeptin) but rarely induces myocyte injury (no change in troponin). These findings suggest a more prevalent cardiac influence from 5-FU and that Holter recording is an important tool in the evaluation of patients with suspected cardiotoxicity from 5-FU.

Fluoropyrimidine-induced cardiotoxicity

Cardio-oncology is a discipline based on early screening, monitoring, and treating chemotherapy-induced cardiotoxicity. There are many chemotherapeutics known for their cardiac toxic effects, including fluoropyrimidines. Fluoropyrimidine represents the cornerstone of many types of cancer and each year almost two million cancer patients undergo this treatment. Fluoropyrimidine-induced cardiotoxicity can be manifested in several forms, from angina pectoris to sudden death. This paper is a review of how the cardiotoxicity of fluoropyrimidines is presented, the mechanisms of its occurrence, its diagnosis, and management.

5-Fluorouracil Rechallenge After Cardiotoxicity

Patient: Male, 66-year-old

Final Diagnosis: Colon adenocarcinoma • ventricular arrhythmia

Symptoms: Cardiac arrest • syncope

Medication: —

Clinical Procedure: Cardiac catheterization • Cardiac Electronic Implantable Device (CEID)

Specialty: Cardiology • General and Internal Medicine • Oncology

Dietary Glycine Prevents FOLFOX Chemotherapy-Induced Heart Injury: A Colorectal Cancer Liver Metastasis Treatment Model in Rats

Introduction: FOLFOX chemotherapy (CTx) is used for the treatment of colorectal liver metastasis (CRLM). Side effects include rare cardiotoxicity, which may limit the application of FOLFOX. Currently, there is no effective strategy to prevent FOLFOX-induced cardiotoxicity. Glycine has been shown to protect livers from CTx-induced injury and oxidative stress, and it reduces platelet aggregation and improves microperfusion. This study tested the hypothesis of glycine being cardioprotective in a rat model of FOLFOX in combination with CRLM. Materials and Methods: The effect of glycine was tested in vitro on human cardiac myocytes (HCMs). To test glycine in vivo Wag/Rij rats with induced CRLM were treated with FOLFOX ±5% dietary glycine. Left ventricle ejection fraction (LVEF), myocardial fibrosis, and apoptosis, also heart fatty acid binding protein (h-FABP) and brain natriuretic peptide levels were monitored. PCR analysis for Collagen type I, II, and brain natriuretic peptide (BNP) in the heart muscle was performed. Results: In vitro glycine had no effect on HCM cell viability. Treatment with FOLFOX resulted in a significant increase of h-FABP levels, increased myocardial fibrosis, and apoptosis as well as increased expression of type I Collagen. Furthermore, FOLFOX caused a decrease of LVEF by 10% (p = 0.028). Dietary glycine prevented FOLFOX-induced myocardial injury by preserving the LVEF and reducing the levels of fibrosis (p = 0.012) and apoptosis (p = 0.015) in vivo. Conclusions: Data presented here demonstrate for the first time that dietary glycine protects the heart against FOLFOX-induced injury during treatment for CRLM.

Cardiotoxicities of 5-Fluorouracil and Other Fluoropyrimidines

OPINION STATEMENT

Fluoropyrimidine (FP) is used to treat a wide range of cancers; however, it is associated with drug-induced vascular toxicity, as well as angina pectoris and coronary spasm. FP has been administered for many years, although the incidence, mechanisms, and appropriate methods for managing its associated cardiovascular toxicities have not been clarified, and the management of these complications has not been standardized. This lack of evidence is not limited to FP. Many trials of anticancer agents have been conducted, excluding patients with heart diseases. Hence, there is a paucity of epidemiological data on cardiovascular adverse events caused by anticancer agents. There have been remarkable improvements in cancer treatment in recent years, with consequent improvements in prognosis. In this context, new cardiovascular toxicities related to new drugs have emerged. We are now compelled to respond to cardiovascular adverse events despite the lack of evidence regarding optimal management. The result has been establishment and rapid maturation of the new academic field of cardio-oncology. Despite the relative lack of evidence, we must review small pieces of evidence that have accumulated to date and make the utmost efforts to provide patients with effective evidence-based medical care. Simultaneously, we urgently need randomized clinical trials to build strong evidence.

5-FU induced cardiotoxicity: case series and review of the literature

Background

5-Fluorouracil (5-FU) is an antimetabolite chemotherapy used for a variety of solid tumors. It has the potential to cause a wide spectrum of cardiotoxicity, ranging from asymptomatic electrocardiographic changes to cardiomyopathy and subsequent cardiac failure. Main body of the abstract: We present two descriptive cases of new-onset severe cardiomyopathy induced by 5-FU followed by a review of the literature.

Conclusion

Our case series emphasizes the importance of early recognition of this rare complication and prompt cessation of 5-FU, as cardiac dysfunction in this context is potentially reversible.

Coronary Artery Vasospasm Induced by 5-fluorouracil: Proposed Mechanisms, Existing Management Options and Future Directions

Cardiovascular disease and cancer are leading contributors to the global disease burden. As a result of cancer therapy-related cardiotoxicities, cardiovascular disease results in significant morbidity and mortality in cancer survivors and patients with active cancer. There is an unmet need for management of cardio-oncology conditions, which is predicted to reach epidemic proportions, and better understanding of their pathophysiology and treatment is urgently required. The proposed mechanisms underlying cardiotoxicity induced by 5-fluorouracil (5-FU) are vascular endothelial damage followed by thrombus formation, ischaemia secondary to coronary artery vasospasm, direct toxicity on myocardium and thrombogenicity. In patients with angina and electrocardiographic evidence of myocardial ischaemia due to chemotherapy-related coronary artery vasospasm, termination of chemotherapy and administration of calcium channel blockers or nitrates can improve ischaemic symptoms. However, coronary artery vasospasm can reoccur with 5-FU re-administration with limited effectiveness of vasodilator prophylaxis observed. While pre-existing coronary artery disease may increase the ischaemic potential of 5-FU, cardiovascular risk factors do not appear to completely predict the development of cardiac complications. Pharmacogenomic studies and genetic profiling may help predict the occurrence and streamline the treatment of 5-FU-induced coronary artery vasospasm. Echocardiographic measures such as the Tei index may help detect subclinical 5-FU cardiotoxicity. Further research is required to explore the cardioprotective effect of agents such as coenzyme complex, GLP-1 analogues and degradation inhibitors on 5-FU-induced coronary artery vasospasm.

Fluoropyrimidine-induced cardiotoxicity

Fluoropyrimidines (5-fluorouracil and capecitabine) are antimetabolite drugs, widely used for the treatment of a variety of cancers, both in adjuvant and in metastatic setting. Although the most common toxicities of these drugs have been extensively studied, robust data and comprehensive characterization still lack concerning fluoropyrimidine-induced cardiotoxicity (FIC), an infrequent but potentially life-threatening toxicity. This review summarizes the current state of knowledge of FIC with special regard to proposed pathogenetic models (coronary vasospasm, endothelium and cardiomyocytes damage, toxic metabolites, dihydropyrimidine dehydrogenase deficiency); risk and predictive factors; efficacy and usefulness in detection of laboratory markers, electrocardiographic changes and cardiac imaging; and specific treatment, including a novel agent, uridine triacetate. The role of alternative chemotherapeutic options, namely raltitrexed and TAS-102, is discussed, and, lastly, we overview the most promising future directions in the research on FIC and development of diagnostic tools, including microRNA technology.

Is it possible to cure childhood acute myeloid leukaemia without significant cardiotoxicity?

Since cardiotoxicity is a life threatening late effect, a reduction of cardiotoxicity in the treatment of acute myeloid leukaemia (AML) is essential. This review is a compilation of the current knowledge about cardiotoxicity after AML treatment and of how future directions in treatment may affect its incidence. A total of six studies concerning AML and cardiotoxicity were identified. The incidence of late subclinical cardiotoxicity varied between 1·3 and 15·3%, and late clinical cardiotoxicity varied between 1·3 and 9·3%. Cumulative dose of anthracyclines (ACs) and history of relapse were the most common risk factors identified. No conclusions could be drawn about new, potentially less toxic ACs. Differences in treatment data and variations in study populations made comparisons uncertain. The echocardiographic techniques used in the majority of the studies are inferior to more modern echocardiographic methods. This decreases reproducibility and may increase the risk of overestimation of cardiotoxicity. In summary, AML cannot be cured today without ACs. However, some ACs may cause less cardiotoxicity than others. Furthermore there is currently no consensus on equipotent doses of ACs and risk factors for cardiotoxicity. Further research including randomized trials is needed to evaluate whether or not the potentially less cardiotoxic agents fulfil their promise.

Phosphorylated Myosin Light Chain 2 (p-MLC2) as a Molecular Marker of Antemortem Coronary Artery Spasm

Background

It is not uncommon that only mild coronary artery stenosis is grossly revealed after a system autopsy. While coronary artery spasm (CAS) is the suspected mechanism of these deaths, no specific biomarker has been identified to suggest antemortem CAS.

Material/Methods

To evaluate the potential of using phosphorylated myosin light chain 2 (p-MLC2) as a diagnostic marker of antemortem CAS, human vascular smooth muscle cells (VSMCs) were cultured and treated with common vasoconstrictors, including prostaglandins F2α (PGF2α), acetylcholine (ACh), and 5-hydroxy tryptamine (5-HT). The p-MLC2 level was examined in the cultured cells using Western blot analysis and in a rat model of spasm provocation tests using immunohistochemistry (IHC). Effects of increased p-MLC2 level on VSMCs contractile activities were assessed in vitro using confocal immunofluorescence assay. Four fatal cases with known antemortem CAS were collected and subject to p-MLC2 detection.

Results

The p-MLC2 was significantly increased in VSMCs after treatments with vasoconstrictors and in the spasm provocation tests. Myofilament was well-organized and densely stained in VSMCs with high p-MLC2 level, but disarrayed in VSMCs with low p-MLC2 level. Three of the 4 autopsied cases showed strongly positive staining of p-MLC2 at the stenosed coronary segment and the adjacent interstitial small arteries. The fourth case was autopsied at the 6th day after death and showed negative-to-mild positive staining of p-MLC2.

Conclusions

p-MLC2 might be a useful marker for diagnosis of antemortem CAS. Autopsy should be performed as soon as possible to collect coronary arteries for detection of p-MLC2.