Q: How is "Reverse use dependence" is defined for any cardiac drug?

Answer: Reverse use dependence is defined as an inverse correlation between the heart rate and the QT interval. As a result, the QT interval is prolonged as the heart rate slows, with an associated risk of drug-induced torsades de pointes -  and a possible decrease in drug efficacy at higher heart rates. This is very co-related with sotalol and other class III antiarrhythmic drugs, except for amiodarone.