Palpitations

Haemodynamic instability (shock, syncope, ischaemia, heart failure) → emergency synchronised DC cardioversion

Paradoxical embolic stroke (a venous clot crossing the defect)

Dysthyroid optic neuropathy (reduced colour vision/acuity, RAPD) → urgent (sight-threatening — see ophthalmology)

Thyroid storm (fever, agitation, tachyarrhythmia, delirium, often precipitated by illness/surgery) → emergency

First presentation: exclude cardiac/respiratory/endocrine cause before labelling

Hypertensive crisis (can be precipitated by anaesthesia, beta-blockade alone, or contrast) → emergency

ARVC with syncope/arrhythmia/family history of sudden death → ICD and exercise restriction

Haemodynamic instability → synchronised DC cardioversion

Distinguish from Graves (high uptake) — antithyroid drugs are inappropriate in thyroiditis

Iron-deficiency anaemia in an adult (especially post-menopausal women / any man) → investigate for GI malignancy (urgent

Suicidal ideation; severe functional impairment → step up care

ECG changes or K+ >6.5 = emergency → calcium first; arrhythmia/cardiac arrest risk

Exertional syncope, family history of sudden death, massive LVH, non-sustained VT or abnormal BP response → high sudden-

Reduced consciousness/seizure; sulfonylurea-induced hypoglycaemia is prolonged → admit/observe

Severe neuroglycopenia (seizures, coma)

Fulminant myocarditis (cardiogenic shock, ventricular arrhythmia, high-grade block) → ICU/mechanical support

Hyperkalaemia with ECG changes (or K ≥6.5) → EMERGENCY: IV calcium gluconate first (cardioprotection) then insulin-dextr

Syncope on EXERTION, while supine, or with palpitations; abnormal ECG; family history of sudden death; structural heart

Pulseless VT or VF → immediate defibrillation + ALS (shockable arm)

Carcinoid crisis (peri-procedure) → octreotide cover

RED-FLAG features that mean refer/echo (NOT innocent): diastolic murmur, pansystolic, loud (≥grade 3)/thrill, harsh, abn

Critical neonatal PS → prostaglandin (duct-dependent) + intervention