A 43 year old woman with a 40 year history of exertional chest pain

A 43 year old Asian woman was referred to the cardiology outpatient clinic with recurrent episodes of chest pain, which she had experienced since early childhood. She described the chest pain as a central tightness that occurred when she exercised. She had recently developed paroxysms of fast regular palpitations, which had prompted her referral. Her only known coronary risk factor was a family history of premature coronary disease. Physical examination was unremarkable and her blood pressure was 110/56 mm Hg. Routine haematology and biochemistry tests, including her thyroid stimulating hormone concentration, were all within normal limits. A 12 lead electrocardiogram (ECG) showed normal sinus rhythm. A 24 hour Holter ECG showed sinus rhythm with occasional supraventricular ectopic beats and no suggestions of any ST segment change (no diary entries). Chest radiography, echocardiography, and pulmonary function tests were unremarkable. She went on to have a Bruce protocol exercise tolerance test. Her ECG at peak exercise (eight minutes) is shown (fig 1⇓).