Triangular QRS-ST-T Waveform Electrocardiographic Pattern in Acute Myopericarditis: A Case Report from a Limited-Resources Hospital

Background

The triangular QRS-ST-T waveform (TW) electrocardiography (ECG) pattern, also known as shark fin pattern, or lambda-like pattern, is an uncommon ECG finding that has been found to be associated with poor prognosis in patients with ST-segment elevation myocardial infarction (STEMI) during the acute phase [1]. The TW pattern identifies a subset of patients at high risk of both ventricular fibrillation (VF) and cardiogenic shock, as well as associated high in-hospital mortality. The incidence of this TW pattern is approximately 1.4% of the population, based on a cohort study of 367 consecutive STEMI patients [2]. A previous study found that TW pattern was significantly more prevalent among the selected population of STEMI complicated by VF compared with the control population of uncomplicated STEMI (48% vs. 4.1% respectively) [3]. Therefore, a prompt and aggressive strategy is needed for patients presenting with this ECG pattern [2]. However, this pattern is rarely present in non-ischemic cardiac diseases. We present a case of a possible non-ischemic cause, namely acute myopericarditis, that presented with the TW ECG pattern, at a limited-resources hospital in a rural area. After the myopericarditis was treated, the ECG pattern returned to normal.

Case Report

A 50-year-old man came to the hospital emergency room with a history of frequent mucoid diarrhea and abdominal cramp for 1 week, and was unable to defecate, had distended abdomen and bilious vomiting 1 day before admission. On physical examination his vital signs were: Blood pressure 110/60 mmHg, heart rate 100 beats per min, respiratory rate 24 breaths per min, and axillary temperature of 36.8°C. Heart and lung evaluations were within normal limits. He and his family had no relevant past medical history of any chronic disease or cardiac disease. However, he was a regular cigarette smoker for 30 years. The abdominal evaluation showed a distended abdomen, increased bowel sound, and bowel movement frequency. His ECG evaluation showed no abnormalities. An abdominal X-ray and ultrasonography evaluation revealed high partial bowel obstruction sign without mechanical cause. Laboratory tests showed leukocytosis (24 100/mm3) with leukocyte differential count shift to the left (neutrophil 79.2%, lymphocyte 13.0%, monocyte 7.4%, and eosinophil 0.1%) and a slightly high pro-calcitonin level (0.55 ng/ml).

Based on the initial evaluation, the patient was diagnosed with partial bowel obstruction and enteritis. We administered 1 g ceftriaxone twice a day for 4 days intravenously and did an abdominal decompression using a nasogastric tube. However, on the second day in the hospital ward, the abdominal distention persisted. Therefore, laparotomy was planned to be done immediately. One hour before the surgery, the patient felt a non-specific chest discomfort with all vital signs within normal limits, indicating a stable hemodynamic. An ECG re-evaluation showed an ST-segment elevation at the anterior and inferior leads (Figure 1). Creatine kinase-MB (CK-MB) evaluation showed a slightly elevated titer (27 U/L). The patient was then diagnosed with STEMI.

Due to the unavailability of coronary angiography at our hospital, the STEMI was treated with a loading dose of dual anti-platelet (aspirin 180 mg and clopidogrel 300 mg) and intravenous nitroglycerin 10 µg/min, followed by a thrombolytic therapy of 100 mg alteplase over 1.5 h infusion. After the thrombolytic procedure, the chest discomfort persisted, and the ECG evaluation revealed a TW pattern in the precordial lead and a diffuse ST-segment elevation in the other leads (Figure 2). Transthoracic echocardiography (TTE) evaluation was performed and revealed minimal to moderate pericardial effusion with normokinetic and normal right and left ventricle systolic function (62% ejection fraction).

Based on these findings, we suspected acute myopericarditis as the diagnosis. A loading dose of 2 mg oral colchicine followed by 1.2 mg once daily and 8 mg methyl prednisolone 3 times daily was then given as treatment for myopericarditis. A computed tomography (CT) scan obtained a few hours after the treatment also supported the diagnosis of myopericarditis. It also showed a mucosal thickening of the ileus, which is a sign of enteritis, suggesting the diagnosis of inflammatory bowel disease (IBD) (Figure 3). Stool testing on the next day (day 3 of hospitalization) showed positive mucous and fecal leukocytes, with negative results for human immunodeficiency virus, hepatitis B virus, and tuberculosis. The diagnosis of the patient was then changed to acute myopericarditis secondary to suspected extra intestinal manifestation of IBD. The patient was then referred to undergo a coronary angiography evaluation, but unfortunately he and his family refused.

Three days after the therapy for myopericarditis was initiated (5th day of hospitalization), the ECG evaluation showed progressive resolution back to normal baseline (Figure 4). Chest pain and abdominal symptoms were also resolved. The patient was then discharged 2 days later (on the 7th day of hospitalization) with oral colchicine 0.6 mg twice daily continued for 3 months and methyl prednisolone tapered off to 8 mg once daily continued for 7 days. He was also given omeprazole 20 mg once daily to prevent any gastric problems related to steroid therapy and was instructed to restrict exercise for at least 3 months. Three months later, the patient came to the outpatient clinic for routine follow-up, with good adherence with the therapy and without any adverse effects. He did not have any remaining symptoms, and the TTE evaluation showed normal findings without any remaining pericardial effusion.

Discussion

STUDY LIMITATIONS:

There was no coronary or CT angiography facility in our hospital, thus coronary involvement could not be totally ruled out and remained as a differential diagnosis. The patient also refused to be referred for further workup for his IBD or possible coronary occlusion. In addition, the titer of antibodies of usual viral myocarditis, such as coxsackie virus, also could not be measured in our hospital. Nevertheless, with the good response of the patient with standard therapy of myopericarditis, and from our available clinical data, we present the first case report of likely myopericarditis with a good outcome as a possible differential cause of TW ECG pattern other than life-threatening ischemic conditions.

Conclusions

The TW ECG pattern indicates the need for prompt management and can appear not only in myocardial infarction, but can also be found in myopericarditis, as in our case. Therefore, myopericarditis should be considered in the differential diagnosis of acute chest pain and ST segment ECG changes, including TW pattern. Unlike TW pattern in STEMI cases which always has a poor prognosis, myopericarditis usually has a good response to medical treatment, as seen in our patient. The use of echocardiography can aid in differentiating the diagnosis when immediate coronary angiography cannot be done.