Patients with Fontan palliation are at a higher risk of thromboembolic events, as well as sudden death. We report a case of acute thromboembolic myocardial infarction in a patient with Fontan circulation, presenting with acute heart failure. Coronary thrombolysis and reperfusion did not improve the myocardial dysfunction and warranted a unique application of mechanical support with Impella 2.5 pump as a bridge to decision. The patient was successfully transplanted. The case highlights the thromboembolic risks and provides support for the early use of mechanical support in such scenarios, even in single ventricle patients.