title: Differential effects of statins (pravastatin or simvastatin) on ventricular ectopic complexes: Galpha(i2), a possible molecular marker for ventricular irritability.
abstract: Retrospective studies suggest that statins might exert an antiarrhythmic effect on the heart. The mechanism of this effect is unclear. Parasympathetic stimulation of the heart has been shown to protect against ventricular arrhythmias. The goal of this study was to determine the effect of statins on ventricular arrhythmias and its correlation with changes in parasympathetic responsiveness and Galpha(i2) expression. Patients were randomized to pravastatin and simvastatin in a double-blind crossover design. Ventricular arrhythmias were determined by analysis of 24-hour Holter recordings. Spectral RR interval analysis of Holter studies determined peak high-frequency power fraction, which reflects parasympathetic modulation of heart rate. Expression of Galpha(i2), a molecular component of the parasympathetic response pathway, was determined by Western blots of patients' lymphocytes. Pravastatin treatment decreased the incidence of ventricular premature complexes by 22.5 + or - 3.4% (n = 20, p <0.05), couplets, and runs of 3 to 6 beats of nonsustained ventricular tachycardia from 9.8 + or - 2.67 to 3.9 + or - 1.25 events/patient/24 hours (n = 12, p <0.05). Pravastatin increased peak high-frequency fraction by 29.8 + or - 4.3% (n = 33, p <0.001), while Galpha(i2) expression increased by 51.3 + or - 22.5% (n = 21, p <0.05). Effects of simvastatin on ventricular premature complexes and nonsustained ventricular tachycardia were not significant. Relative changes in couplets and nonsustained ventricular tachycardia in pravastatin-treated patients correlated negatively with changes in Galpha(i2) and high-frequency fraction (rho = -0.588 and rho = -0.763, respectively, n = 12, p <0.05). In conclusion, these data suggest that pravastatin might decrease cardiac irritability via an increase in parasympathetic responsiveness and that changes in Galpha(i2) expression might serve as a molecular marker for this effect, which might play a role in the molecular mechanism of the antiarrhythmic effect of statins.
authors.affiliation: Molecular Cardiology Research Institute, Tufts Medical Center, Tufts University School of Medicine, Boston, MA, USA.
authors.forename: C Michael
authors.initials: CM
authors.lastname: Welzig
authors.forename: Ho-Jin
authors.initials: HJ
authors.lastname: Park
authors.forename: Jack
authors.initials: J
authors.lastname: Naggar
authors.forename: Deborah
authors.initials: D
authors.lastname: Confalone
authors.forename: Joanne
authors.initials: J
authors.lastname: Rhofiry
authors.forename: Julie
authors.initials: J
authors.lastname: Shea
authors.forename: Richard H
authors.initials: RH
authors.lastname: Karas
authors.forename: N A Mark
authors.initials: NA
authors.lastname: Estes
authors.forename: Jonas B
authors.initials: JB
authors.lastname: Galper
mesh_terms: D000328:Adult; D000368:Aged; D015415:Biomarkers / Q000097:blood*; D015153:Blotting, Western; D018592:Cross-Over Studies; D003720:Densitometry; D004305:Dose-Response Relationship, Drug; D004311:Double-Blind Method; D015716:Electrocardiography, Ambulatory; D005260:Female; D005500:Follow-Up Studies; D051960:GTP-Binding Protein alpha Subunit, Gi2 / Q000096:biosynthesis* / Q000097:blood; D006801:Humans; D019161:Hydroxymethylglutaryl-CoA Reductase Inhibitors / Q000008:administration & dosage* / Q000627:therapeutic use; D008297:Male; D008875:Middle Aged; D017035:Pravastatin / Q000008:administration & dosage* / Q000627:therapeutic use; D011379:Prognosis; D012189:Retrospective Studies; D019821:Simvastatin / Q000008:administration & dosage* / Q000627:therapeutic use; D016896:Treatment Outcome; D018879:Ventricular Premature Complexes / Q000097:blood / Q000188:drug therapy* / Q000503:physiopathology
chemical_list: D015415:Biomarkers; D019161:Hydroxymethylglutaryl-CoA Reductase Inhibitors; D019821:Simvastatin; D051960:GTP-Binding Protein alpha Subunit, Gi2; D017035:Pravastatin