Cardiac disease is one of the commonest causes of indirect maternal deaths globally. This brief report is a reminder that isolated maternal tachycardia at rest is a clinical alert and warrants a detailed history in relation to cardiac disorders, thorough clinical examination of all organ systems, relevant investigations such as imaging, and expert advice to avoid serious adverse events. We reflect on a belatedly investigated persistent maternal tachycardia resulting in a fatal postpartum collapse due to mitral stenosis. The lost window of opportunity for appropriate investigation and management of the tachycardia provides an insight into many similar maternal deaths in South Africa. Key clinical messages regarding persistent maternal tachycardia are presented for midwives and doctors caring for pregnant women