Primary percutaneous coronary intervention (PPCI) is the most effective therapy for patients with an acute ST-segment elevation myocardial infarction (STEMI). However, up to half of STEMI patients suffer from coronary microvascular dysfunction, presenting as the slow flow or no-flow phenomenon. A 50 years male patient admitted with acute anterior wall myocardial infarction, PPCI was performed on the patient. After thrombus aspiration, a stent was placed in the proximal LAD. As coronary angiography showed slow flow in LAD, 6mg nicorandil was administrated intra-coronary. Immediately, cardiac arrest occurred and cardiopulmonary resuscitation (CPR) was performed.