Effects of lidocaine and droxicainide on myocardial necrosis: a comparative study.

Lidocaine has been shown to protect ischemic myocardium, but the degree of its effectiveness is not yet well established. Therefore, in this study, the effects of this drug on ultimate infarct size were examined quantitatively. Another member of the same class of drugs, droxicainide (ALS1249), DL-N-(2-hydroxyethyl)-pipecolinyl-2,6-dimethylanilide hydrochloride, is a new antiarrhythmic agent that has shown a good therapeutic index in the initial experimental studies. Accordingly, the effects of this drug on ultimate infarct size were examined and compared with those of lidocaine. Coronary artery occlusion was performed on 29 dogs. One minute later, technetium-99m labeled microspheres were injected into the left atrium for assessment of the hypoperfused zone (the zone at risk of infarction). Fifteen minutes after occlusion, the dogs were randomized into three groups: 9 dogs served as a control group, 10 were given lidocaine and 10 were given the same dosage of droxicainide. Six hours after occlusion, the dogs were sacrificed and the hearts cut into 3 mm thick slices and incubated in triphenyltetrazolium chloride to delineate the area of myocardial damage. Autoradiography of the same slices provided images of the areas of myocardial hypoperfusion. Thereafter, in each dog, the percent of hypoperfused area that evolved to necrosis was calculated. In control dogs, it was 85.6 +/- 2.0%; in lidocaine-treated dogs, 68.1 +/- 4.1% (p less than 0.01), a reduction of 20%; and in droxicainide-treated dogs, 50.1 +/- 5.3%, a reduction of 41% (p less than 0.001 versus control and p less than 0.005 versus lidocaine).