LUCAS FARACO SOBRADO
Projetos de Pesquisa
Unidades Organizacionais
Instituto Central, Hospital das Clínicas, Faculdade de Medicina
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- Selective late sodium current blockade with GS-458967 markedly reduces ischemia-induced atrial and ventricular repolarization alternans and ECG heterogeneity(2014) BONATTI, Rodolfo; SILVA, Ana Flavia Garcia; BATATINHA, Americo Pereira; SOBRADO, Lucas F.; MACHADO, Ananda Dianni; VARONE, Bruno B.; NEARING, Bruce D.; BELARDINELLI, Luiz; VERRIER, Richard L.BACKGROUND Ischemic heart disease is associated with dual risk for atrial and ventricular arrhythmias. OBJECTIVE We examined whether selectively targeting late sodium channel current (I-Na) with 65-458967 (hereafter 65967) can reduce cardiac electrical instability and compared its effects to a clinically relevant dose of flecainide. METHODS Electrode catheters were positioned on the left atrial appendage and left ventricle of anesthetized pigs to monitor repolarization alternans and electrocardiographic heterogeneity before and during left circumflex coronary artery stenosis (75% flow reduction) before and after GS967 (0.4 mg/kg, intravenously [IV]) or ftecainide (1 mg/kg, IV, bolus over 2 minutes followed by 1 mg/(kg . h), IV, for 1 hour) administration. RESULTS Left circumflex coronary artery stenosis increased atrial repolarization alternans by 520% (from 9.4 +/- 1.2 to 58.3 +/- 11.3 mu V; P = .029) and 1-wave alternans by 1038% (from 30.7 +/- 8.2 to 349.3 +/- 103.8 mu V; P = .049). GS967 prevented ischemia-induced increases in alternans in the left atrium (9.3 +/- 5.6 mu V vs 58.3 +/- 11.3 mu V; P = .023) and Left ventricle (217.9 +/- 95.8 mu V vs 349.3 +/- 103.8 mu V; P < .001) (n = 7). GS967 reduced ischemia-induced increases in depolarization heterogeneity (atrium: from 45% to 28%; ventricle: from 92% to 51%) and repolarization heterogeneity (atrium: 43% to 23%; ventricle: 137% to 91%). GS967 did not alter heart rate, arterial blood pressure, PR and QT intervals, or QRS duration, but it mildly decreased contractility (left ventricular dP/dt) during ischemia, which was consistent with late I-Na inhibition. Flecainide (n = 7) amplified ischemia-induced increase in atrial and ventricular repolarization alternans, electrocardiographic heterogeneity, and ventricular fibrillation incidence. CONCLUSION Selective late IN, inhibition with 65967 exerts potent protective effects against ischemia-induced depolarization and repolarization abnormalities in both atria and ventricles.