Cardioversion and 'false positive' technetium 99m stannous pyrophosphate myocardial scintigrams

The present studies performed in experimental animals demonstrate that electrical direct current cardioversion can produce skeletal muscle damage and increased technetium 99m stannous pyrophosphate [⁹⁹(m)Tc PYP] uptake; in experimental animals the electrically damaged skeletal muscle shows necrosis with extensive calcium deposition. In addition, the frequent administration of high energy cardioversion produces myocardial necrosis with calcium deposition, increased ⁹⁹(m)Tc PYP myocardial uptake and a positive ⁹⁹(m)Tc PYP myocardial scintigram. The data indicate that, if diagnostic ⁹⁹(m)Tc PYP myocardial scintigraphy is contemplated after cardioversion, paddle placement should be slightly removed from the anteroposterior projection of the heart on the external chest wall to avoid possible subsequent confusion between increased myocardial and skeletal muscle uptake of ⁹⁹(m)Tc PYP. If multiple high energy cardioversion episodes are necessary, myocardial necrosis resulting from electrical injury may occur and be responsible for increased myocardial uptake of ⁹⁹(m)Tc PYP with a resultant positive ⁹⁹(m)Tc PYP myocardial scintigram.