Persistent ST-segment elevation mimicking ST-elevation myocardial infarction

Abstract

ST-segment elevation on electrocardiography is classically associated with acute myocardial infarction and often prompts urgent invasive evaluation. However, non-ischemic causes may complicate diagnostic decision-making, particularly in elderly patients with acute non-cardiac illnesses. We report a 95-year-old woman admitted with COVID-19–associated pneumonia and aspiration pneumonia, whose admission electrocardiogram demonstrated ST-segment elevation with T-wave inversion in the lateral precordial leads, mimicking ST-elevation myocardial infarction. She had no chest pain, no elevation of cardiac biomarkers, and preserved left ventricular systolic function without regional wall motion abnormalities on echocardiography. Review of prior records revealed that similar electrocardiographic abnormalities had been consistently present for more than a decade. Serial imaging demonstrated no overt structural heart disease. However, the electrocardiographic pattern—localized and persistent ST-segment elevation with repolarization abnormalities—is most consistent with chronic localized myocardial remodeling, possibly related to unrecognized myocardial fibrosis. This case highlights the importance of integrating clinical presentation, biomarkers, and longitudinal electrocardiographic findings. Persistent ST-segment elevation does not always indicate acute coronary occlusion, but may reflect an underlying structural myocardial substrate not detectable by routine imaging.

Introduction

ST-segment elevation on electrocardiography (ECG) is classically associated with acute myocardial infarction and represents a medical emergency requiring prompt evaluation and management.^1,2 Accordingly, the exclusion of ST-elevation myocardial infarction (STEMI) remains a primary clinical priority whenever ST-segment elevation is identified.

However, it is increasingly recognized that ST-segment elevation is not specific to acute coronary occlusion. A wide spectrum of non-ischemic and non-occlusive conditions—including cardiomyopathies, pericarditis, myocarditis, left ventricular aneurysm, and repolarization abnormalities—may produce similar ECG findings.^3–5 Recent conceptual frameworks have further emphasized the distinction between electrocardiographic ST-segment elevation and true coronary occlusion, highlighting the importance of integrating clinical presentation, biomarkers, and imaging findings in diagnostic decision-making.^6,7

This diagnostic challenge is particularly relevant in elderly patients, who often present with atypical or absent ischemic symptoms and frequently have concomitant non-cardiac illnesses that may confound clinical assessment. ⁸ Persistent or long-standing ST-segment elevation without overt structural heart disease is uncommon, especially in advanced age.

We report a very elderly patient with long-standing, stable ST-segment elevation mimicking STEMI, in whom careful longitudinal evaluation allowed avoidance of unnecessary invasive procedures and suggested an underlying chronic myocardial substrate.

Case presentation

A 95-year-old woman was admitted with fever, cough, and hypoxemia. She was diagnosed with coronavirus disease 2019 (COVID-19)-associated pneumonia complicated by aspiration pneumonia. She had no prior history of ischemic heart disease, cardiomyopathy, or valvular heart disease.

The admission electrocardiogram demonstrated ST-segment elevation predominantly in leads V4–V6. The ST-segment morphology was relatively concave, accompanied by T-wave inversion. J-point elevation was clearly observed in the lateral precordial leads, without reciprocal ST-segment depression in other leads (Figure 1). The abnormalities were localized rather than diffuse, and no dynamic changes were observed on serial recordings.

Figure 1.

Electrocardiogram on admission.

Despite these findings, the patient reported no chest pain or chest discomfort. Serial measurements of cardiac biomarkers, including troponin, showed no elevation. According to the Fourth Universal Definition of Myocardial Infarction, myocardial infarction requires evidence of myocardial injury with a rise and/or fall in cardiac biomarkers in a clinical setting consistent with ischemia, which was not observed in this patient. ¹

Review of prior medical records revealed that similar ST-segment elevation had been consistently documented since the age of 83 years (Figure 2). During this period, repeated transthoracic echocardiography demonstrated preserved left ventricular systolic function without regional wall motion abnormalities, left ventricular hypertrophy, or significant valvular disease.

Figure 2.

Long-term electrocardiographic follow-up.

Given the absence of ischemic symptoms, stable ECG findings over more than a decade, and normal cardiac imaging, acute coronary syndrome was considered unlikely. The patient was treated conservatively for pneumonia and recovered without any cardiac events.

Discussion

ST-segment elevation is classically associated with acute myocardial infarction and necessitates urgent evaluation. However, it is now well established that ST-segment elevation is not specific to acute coronary occlusion, and a broad spectrum of non-ischemic and non-occlusive conditions may produce similar electrocardiographic findings.^3–5 Contemporary clinical paradigms further distinguish between electrocardiographic ST-segment elevation and true coronary occlusion, emphasizing the need for comprehensive clinical assessment.^6,7

In the present case, acute myocardial infarction was considered unlikely due to the absence of chest pain, lack of biomarker elevation, and the remarkable long-term stability of the electrocardiographic abnormalities over more than a decade. The absence of dynamic electrocardiographic changes further argues strongly against an acute ischemic process.

Persistent, localized ST-segment elevation is most often associated with an underlying structural myocardial substrate. Chronic myocardial scar, either ischemic or non-ischemic in origin, is a well-recognized cause and may result from prior silent myocardial infarction or resolved myocarditis with residual fibrosis.^9–11 In addition, localized ventricular remodeling, including variants of left ventricular aneurysm, may produce persistent ST-segment elevation even in the absence of overt wall motion abnormalities on echocardiography. ⁹ Importantly, transthoracic echocardiography may not detect subtle or focal myocardial fibrosis, particularly when the abnormality is limited in extent. Advanced imaging modalities such as cardiac magnetic resonance imaging provide superior tissue characterization and are more sensitive for detecting myocardial scar or fibrosis. ¹⁰

In contrast, non-structural causes of ST-segment elevation appear less likely in this case. Early repolarization is typically observed in younger individuals and is less commonly associated with persistent T-wave inversion.^12,13 Acute pericarditis, myocarditis, and Takotsubo syndrome generally present with dynamic electrocardiographic changes and/or biomarker elevation, neither of which were observed in this patient.^14–16

Taken together, the electrocardiographic pattern observed in this case—persistent, localized ST-segment elevation with associated T-wave inversion—is most consistent with chronic localized myocardial remodeling, possibly reflecting an underlying fibrotic substrate that remained clinically silent. Although cardiac magnetic resonance imaging would have provided valuable additional information regarding myocardial tissue characteristics, it was not performed due to clinical considerations in this very elderly patient.

The underlying mechanism should be considered presumptive rather than definitive. While a chronic structural myocardial substrate, such as fibrosis or localized scar, represents the most likely explanation, direct evidence is lacking in this case. Importantly, such electrocardiographic abnormalities should not be regarded as benign or fully understood, as they may reflect underlying myocardial pathology that is not readily detectable by conventional evaluation. Therefore, cautious interpretation is warranted, and further investigation may be necessary when similar findings are encountered in clinical practice.

Conclusion

This case highlights the importance of longitudinal electrocardiographic comparison in distinguishing persistent abnormalities from acute pathological processes. In elderly patients, particularly those with acute non-cardiac illness, careful integration of clinical findings, cardiac biomarkers, and electrocardiographic patterns is essential to avoid misdiagnosis and unnecessary invasive procedures. Furthermore, it underscores that persistent ST-segment elevation should not be assumed to be benign, but rather interpreted within the context of a potential underlying structural myocardial substrate.