Technetium-99m-pyrophosphate (99mTc-PYP) has been used, in combination with thallium-201, to estimate the site and extent of myocardial infarcts. We report a case of acute myocardial infarction with severe coronary disease in which the distribution of 99mTc-PYP was extensive. A 78-year-old man presented with dyspnea, and a diagnosis of non-ST-segment elevation acute myocardial infarction was made. Emergency coronary angiography revealed total occlusion of the proximal portion of the right coronary artery and left circumflex coronary artery with collateral flow from the left anterior descending coronary artery, which also had severe stenoses. Given his comorbidities and preferences, subsequent angioplasty was waived. Dual myocardial scintigraphic imaging, which was performed four days after admission, demonstrated slightly reduced thallium-201 uptake in the inferior wall and apex, whereas 99mTc-PYP was positive in the entire left ventricular subendocardial region and the free wall of the right ventricle. His clinical course was uneventful with conservative treatment and the patient was discharged 20 days after admission in a stable condition.