Slow coronary flow is an angiographic phenomenon characterized by delayed opacification of vessels in the absence of any evidence of obstructive epicardial coronary disease. In this article, we present serious clinical manifestations of extremely slow coronary flow in two hypertensive patients with preserved ejection fraction in echocardiographical examination: a 57 year-old woman with acute coronary syndrome and temporary ST elevation; and a 65 year-old man with atrial tachycardia which was leading to sudden arrest of circulation. The woman was admitted to hospital due to recurrent syncope and chest pain. Because of severe bradycardia, an AAI pacemaker was implanted. Coronary angiography without evident obstructive lesion revealed extremel...