An 84-year-old woman was diagnosed with atrial septal defect (ASD) accompanied by multiple holes in 2007. In March 2015, she was admitted with congestive heart failure due to ASD. Surgical closure was recommended because her pulmonary to systemic flow ratio was 1.8, but she declined due to her advanced age. In August 2015, she developed acute inferior myocardial infarction, and coronary angiography showed an occluded proximal right coronary artery. Direct percutaneous coronary angioplasty was successfully performed. After the operation, her condition was stable, but she suddenly fell into refractory hypoxemia on the day after admission. Transthoracic echocardiogram showed acute right-to-left shunting through ASD. Although surgical closure was again recommended, her family asked for conservative medical treatment, not surgical treatment. She ultimately died in spite of medical treatment. Some case reports documented that right ventricular infarctions were complicated by refractory hypoxemia with right-to-left shunting through patent foramen ovale (PFO) or ASD. In the present case, various causes for the right-to-left shunting were considered, e.g., a shift in inferior vena cava flow associated with a stretched atrial septum or a shift in tricuspid regurgitation flow associated with a pacemaker lead. We report this case with a review of some of the literature on right-to-left shunting through PFO or ASD in inferior myocardial infraction.