ST-Segment Elevation – Where’s the Myocardial Infarction?

Abstract

ST-Segment Elevation – Where’s the Myocardial Infarction?

Nuno Magalhães, Rui Filipe Gomes, Ana Raquel Gomes, Mariana Alves, Anabela Oliveira

Medicina Interna, ULS Santa Maria, Lisboa Portugal

In the emergency department (ED), ST-segment elevation typically prompts immediate investigation for suspected acute myocardial infarction (AMI). However, it is essential to recognize that not all ST-segment changes correspond to Acute Coronary Syndrome (ACS), and a careful, systematic exclusion of life-threatening causes—particularly AMI—remains a clinical priority (1, 2, 3).

We report the case of a 60-year-old male with a background of dwarfism, renal lithiasis, and bladder neoplasia, who presented to the ED following a syncopal episode. He denied chest pain or dyspnea but reported months-long hematuria, being under regular urological follow-up. On physical examination, he was hemodynamically stable, afebrile, and eupneic. The admission ECG showed sinus rhythm, ST-segment elevation in leads V1-V4, and hyperacute T waves (Figure 1), leading to immediate transfer to the resuscitation area and initiation of ACS workup.

A bedside transthoracic echocardiogram revealed preserved global systolic function and no segmental wall motion abnormalities, suggesting a low likelihood of AMI. Laboratory tests demonstrated hemoglobin of 11.3 g/dL, acute kidney injury (creatinine 2.84 mg/dL), significant hyperkalemia (7.6 mmol/L), and metabolic acidemia (pH 7.398), with normal cardiac injury biomarkers.

Urgent potassium-lowering therapy led to a partial reduction in serum potassium (6.9 mmol/L), without elevation in cardiac markers. A repeat ECG revealed resolution of the ST-segment elevation but persistence of hyperacute T waves (Figure 2). Abdominopelvic CT identified bilateral ureterohydronephrosis. Following dialysis, ECG abnormalities fully resolved, and the patient was referred to Urology for ongoing management of obstructive nephropathy.

This case illustrates a rare presentation of hyperkalemia with ST-segment elevation and underscores the importance of maintaining a broad differential diagnosis. Nevertheless, it is essential to rigorously exclude Acute Coronary Syndrome (ACS) in the presence of ST-segment changes.