Clinical Introduction A female in her 90s was admitted to the hyper-acute stroke unit following an ischaemic left thalamic stroke, with a resultant dense right-sided hemiparesis. She has no significant cardiac history and has had no previous surgical interventions. Following the stroke, she had been started on aspirin 75 mg once a day, clopidogrel 75 mg once a day and atorvastatin 80 mg once nightly. A geko device was applied to minimise the risk of venous thromboembolism. She was commenced on cardiac monitoring for the detection of atrial fibrillation. While on the monitor, she was noted to be bradycardic with heart rates of 40 beats per minute. A 12-lead ECG was performed (figure 1). Figure 112-lead ECG during period of bradycardia. Question What does this ECG show? Atrial fibrillation with frequent ventricular ectopics Pacemaker dysfunction secondary to undersensing ...