Data from: Effects of the selective stretch-activated channel blocker GsMtx4 on stretch-induced changes in refractoriness in isolated rat hearts and on ventricular premature beats and arrhythmias after coronary occlusion in swine

Mechanical factors may contribute to ischemic ventricular arrhythmias.
GsMtx4 peptide, a selective stretch-activated channel blocker, inhibits
stretch-induced atrial arrhythmias. We aimed to assess whether GsMtx4
protects against ventricular ectopy and arrhythmias following coronary
occlusion in swine. First, the effects of 170-nM GsMtx4 on the changes in
the effective refractory period (ERP) induced by left ventricular (LV)
dilatation were assessed in 8 isolated rat hearts. Then, 44 anesthetized,
open-chest pigs subjected to 50-min left anterior descending artery
occlusion and 2-h reperfusion were blindly allocated to GsMtx4 (57 μg/kg
iv. bolus and 3.8 μg/kg/min infusion, calculated to attain the above
concentration in plasma) or saline, starting 5-min before occlusion and
continuing until after reflow. In rat hearts, LV distension induced
progressive reductions in ERP (35±2, 32±2, and 29±2 ms at 0, 20, and 40
mmHg of LV end-diastolic pressure, respectively, P<0.001) that were
prevented by GsMTx4 (33±2, 33±2, and 32±2 ms, respectively, P=0.002 for
the interaction with LV end-diastolic pressure). Pigs receiving GsMtx4 had
similar number of ventricular premature beats during the ischemic period
as control pigs (110±28 vs. 103±21, respectively, P=0.842). There were not
significant differences among treated and untreated animals in the
incidence of ventricular fibrillation (13.6 vs. 22.7%, respectively,
P=0.696) or tachycardia (36.4 vs. 50.0%, P=0.361) or in the number of
ventricular tachycardia episodes during the occlusion period (1.8±0.7 vs.
5.5±2.6, P=0.323). Thus, GsMtx4 administered under these conditions does
not suppress ventricular ectopy following coronary occlusion in swine.
Whether it might protect against malignant arrhythmias should be tested in
studies powered for these outcomes.