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.