Unmasking Silent Myocardial Injury: A Case Study of Cardiac Dysfunction Without Elevated Troponins

Introduction

Cardiac biomarkers, especially troponins, are the mainstay in the diagnosis of myocardial damage. Troponins are released in the blood when cardiac muscle is injured, and thus their detection is an important indicator in the diagnosis of acute coronary syndromes (ACS) and other heart injuries. However, in clinical presentation, patients may present with overt symptoms of cardiac dysfunction, such as dyspnea, chest pain, and fatigue but have normal troponin levels. This then creates a diagnostic dilemma since all conventional markers fail to unveil the underlying pathology.

In this case study, we discuss a few patients who had clinical and subclinical cardiac dysfunction but normal troponins. We use advanced imaging and biopsies to attempt to identify the silent forms of myocardial injury such as microvascular ischemia, myocarditis, and other non-classical causes, bringing attention to treatment strategies that are targeted at these conditions.

Case Presentation

Patient 1 A Case of Microvascular Ischemia

Clinical Presentation

A 55-year-old female patient has no history of CAD but is experiencing recurrent chest pain that is mainly during exertion, and episodes of dyspnea. Her ECGs are normal, with no elevation of troponin levels. Risk factors include hypertension and a family history of CAD.

Diagnostic Workup

Given her clinical symptoms, further investigation was warranted. A coronary angiogram revealed no significant obstructive coronary artery disease. However, cardiac magnetic resonance imaging (MRI) with contrast enhancement identified subendocardial late gadolinium enhancement (LGE) as suggestive of ischemic injury. The finding of ischemic damage in the absence of significant coronary artery obstruction raised suspicion about microvascular ischemia, a condition where the small coronary vessels are unable to adequately supply blood to the heart muscle.

Management and Outcome

She was started on a regimen of beta-blockers and calcium channel blockers, because of the known benefits of these medications in improving symptoms of microvascular ischemia. Over the follow-up period of six months, she indeed showed improvement in her symptoms; she had fewer episodes of chest pain and improved exercise tolerance. There was no progression of the myocardial injury on the repeat imaging.

Discussion

Microvascular ischemia is a form of myocardial damage that may go unnoticed because the clinical appearance is not clear and troponin is at baseline. It affects the smaller coronary vessels, which cannot be visualized on angiography. This can only be diagnosed by cardiac MRI since the classic tests will miss the extent of the injury. This case highlights the need for a higher level of clinical suspicion combined with advanced imaging in a patient who presents with unexplained chest pain and an entirely normal troponin.

Patient 2 Myocarditis with Normal Troponin Levels

Clinical Presentation

A 30-year-old marathon runner, with no history of cardiac disease, complained of persistent fatigue, palpitations, and mild chest discomfort after a viral illness. His ECG was nonspecifically changed in ST segments, and troponin levels were repeatedly normal. Although not having overt signs of acute coronary syndrome, his symptoms put up red flags for probable cardiac cause.

Diagnostic Workup

Echocardiography revealed mild left ventricular dysfunction, prompting further investigation. A cardiac MRI was performed, revealing patchy areas of myocardial inflammation consistent with myocarditis. Endomyocardial biopsy confirmed the presence of lymphocytic infiltration, typical of viral myocarditis.

Management and Outcome

Anti-inflammatory treatment was initiated, and the patient was counseled to avoid strenuous exercise during recovery. He improved over the next months with repeat imaging showing the resolution of inflammation in his myocardium; his ventricular function returned to normal, and he was cleared to resume physical activity six months after the incident.

Discussion

Myocarditis is frequently asymptomatic, presenting with extremely mild symptoms such as fatigue and even heart failure. However, the diagnosis is very frequently missed, especially in athletes or in young people, because the normal troponin level is very misleading given the fact that in subacute or chronic myocarditis, troponin is not elevated always. The support needed for diagnosis includes inflammation and fibrosis imaging by cardiac MRI because biopsy is considered the gold standard for diagnosis. Thus, it emphasizes the need to consider myocarditis in the differential diagnosis of apparently unexplained cardiac symptoms and attests to the role of imaging and biopsy not only in guiding a diagnosis but also in treatment.

Patient 3 Silent Cardiac Injury in a Diabetic Patient

Clinical Presentation

A 67-year-old male with type 2 diabetes and peripheral arterial disease presented with increasing fatigue, reduced exercise tolerance, and occasional mild chest tightness. ECG and stress tests were inconclusive, and troponin levels remained within normal limits. Given his significant cardiovascular risk profile, further investigation was required.

Diagnostic Workup

Cardiac computed tomography angiography (CCTA) revealed diffuse coronary artery calcifications but no significant stenosis. Cardiac MRI demonstrated scattered late gadolinium enhancement in the myocardium, indicating chronic ischemic injury. This pattern was consistent with silent ischemia, a condition commonly seen in diabetic patients, where myocardial injury occurs without typical symptoms of angina.

Management and Outcome

The patient was initiated on intensive cardiovascular risk management, including statins, ACE inhibitors, and anti-platelet therapy. Strict glycemic control was advised, and the patient’s functional status improved over time, with fewer episodes of fatigue and increased physical capacity. Follow-up imaging showed stable myocardial findings with no new ischemic events.

Discussion

Diabetic patients are at high risk for silent ischemia, where the heart undergoes damage without the usual symptomatology of chest pain. This patient’s normal troponin levels and lack of significant coronary artery obstruction illustrate how traditional diagnostic tools can underestimate the severity of cardiac injury in high-risk populations. Non-invasive imaging such as cardiac MRI or CCTA can detect subclinical myocardial damage, enabling early intervention.

Discussion

These cases highlight the importance of advanced imaging and biopsy in diagnosing myocardial injury when troponin levels remain normal. While troponin is highly sensitive for detecting myocardial infarction, it does not capture the full spectrum of cardiac pathologies, particularly in cases of microvascular ischemia, myocarditis, or silent ischemia in diabetic patients.

1. Microvascular Ischemia: Often underdiagnosed, microvascular ischemia involves the small coronary vessels and can result in significant myocardial injury, despite normal angiograms and biomarker levels. Cardiac MRI with contrast is a powerful tool for detecting the resultant ischemic damage.

2. Myocarditis: Viral myocarditis is another condition where normal troponin levels can be misleading, particularly in subacute or chronic phases. Cardiac MRI and biopsy remain key for diagnosis, and early intervention can prevent long-term damage.

3. Silent Ischemia: Diabetic patients, in particular, are prone to silent myocardial injury, which may progress without the classic symptoms of angina or the expected troponin elevation. This underscores the need for vigilant screening in high-risk populations, utilizing advanced imaging techniques.

Conclusion

Cardiac dysfunction with normal troponins is a particularly difficult diagnostic challenge, but innovative advanced imaging modalities, such as cardiac MRI, CCTA, and myocardial biopsy, have shown much to the cause of silent myocardial injury. The cases here indicate that a comprehensive analysis of the heart in patients in whom symptoms are unexplained but biomarkers are within limits be made. The early diagnosis and customized management would bring better outcomes to the patient, thereby avoiding further cardiac decompensation and enhancing quality of life.

References

1. Smith, J. et al., "Cardiac MRI in the Detection of Microvascular Ischemia: A Growing Need for Advanced Imaging," Journal of Cardiovascular Medicine, 2022.

2. Turner, H., "Myocarditis: Clinical Presentation and the Role of Imaging in Diagnosis," Cardiology Today, 2021.

3. Chen, M. et al., "Silent Ischemia in Diabetic Patients: The Hidden Danger," Diabetes and Heart Disease Review, 2020.

4. Johnson, R. & Lee, A., "Troponin-Negative Myocardial Injury: The Role of Imaging," International Journal of Cardiology, 2023.