Polymorphic ventricular tachycardia, which occurs during the subacute phase of myocardial infarction (MI) or ischemia and is not related to ongoing ischemia, has recently been reported. It has characteristics of typical pause-dependent torsades de pointes (TdP) following excessive QT prolongation (post MI/ischemia-associated TdP). We describe a male patient with post MI/ischemia-associated TdP. The patient experienced recurrent TdP with excessive QT prolongation 2 days after transient myocardial ischemia. Genetic screening of the major LQTS-causing genes identified a KCNQ1 G643S variant. This gene variant could be a genetic predisposition to the development of TdP during the subacute phase of MI/ischemia.