Case Presentation
A 76 years-old lady with hypertension and previous history of total thyroidectomy in 2017 was brought to a local emergency department with a two-day history of vague generalized weakness and poor oral intake. Premorbidly, she stayed alone and was visited by her family members regularly. Her previous oral medications include Amlodipine/ Valsartan combination and L-Thyroxine. The initial 12-lead ECG demonstrated generalised “triangular” QRS-ST-T waveform mimicking a “shark fin pattern” (Figure 1A). She was then transferred to the regional percutaneous coronary intervention (PCI) centre for further evaluation of acute silent myocardial infarction. Assessment on arrival revealed no angina symptoms but a more detailed history could not be elicited due to delirium as well as lack of collateral history from her family. Physical examination showed a frail and dehydrated patient, with blood pressure of 79/51mmHg, with a heart rate of 112 beats per minute. Neurological examination was unremarkable. Bedside echocardiography revealed normal ejection fraction, with no evidence of pericardial effusion or regional wall motion anomalies. Laboratory investigations showed a raised Troponin T of 46ng/L (Roche Elecsys). Other routine biochemistry studies were notable for potassium concentration of 2.3mmol/l, corrected calcium concentration of 1.41mmol/l, phosphate of 1.39mmol/l, albumin of 36g/L as well as creatinine level of 116umol/L. pH was 7.58, pCO2 31mmHg, pO2 67mmHg, HCO3 29.1mmol/L. A preliminary diagnosis of electrolyte induced ECG changes was made, for which she was commenced on intravenous replacement infusion. Further investigation was remarkable for serum intact parathyroid hormone of <1.2 pmol/L (reference range 1.6-6.9 pmol/L). With careful electrolyte correction and hydration, as well as close interval monitoring, she improved clinically and the ECG changes resolved as potassium and calcium concentrations normalised (Figure 1B). She was subsequently able to provide a clearer history of diarrhoea episodes during the period of feeling unwell. No further invasive coronary study was performed as there was resolution of ECG changes following correction of electrolytes and dehydration. ECG repeated prior to discharge did not show any ST-T changes (Figure 1C). At follow-up about 3 months later, she remained asymptomatic of angina.