title: New insights into the beneficial electrophysiologic profile of ranolazine in heart failure: prevention of ventricular fibrillation with increased postrepolarization refractoriness and without drug-induced proarrhythmia.
abstract: BACKGROUND
  Ranolazine inhibits late Na(+) and K(+) currents. Earlier studies have reported an antiarrhythmic effect. The aim of the present study was to understand whether ranolazine could still preserve its antiarrhythmic properties in the settings of chronic heart failure (CHF).
  
  
  RESULTS
  In 12 female rabbits, CHF was induced by 4 weeks of rapid ventricular pacing leading to a decrease in ejection fraction. Twelve rabbits underwent sham operation. Isolated hearts were Langendorff perfused and demonstrated a significant QT prolongation after induction of heart failure. Ranolazine caused a concentration-dependent (10 and 30 μmol/L) increase of action potential duration (APD(90)) in sham-operated and failing hearts. Eight endo- and epicardial monophasic action potentials revealed a nonsignificant increase in spatial and temporal dispersion of repolarization. The increase in APD(90) was accompanied by a greater increase in refractory period, resulting in a significant increase in postrepolarization refractoriness in sham-operated (+29 ms and +55 ms; P < .01) and failing (+22 ms and +30 ms; P < .05) hearts. In control conditions, programmed ventricular stimulation and a burst pacing protocol led to ventricular fibrillation (VF) in 5 of the 12 sham-operated (6 episodes) and in 7 of the 12 failing (18 episodes) hearts. In the presence of ranolazine, VF was inducible in only 2 of 12 failing hearts (5 episodes). In the presence of low [K(+)], only 1 ranolazine-treated sham-operated heart developed early afterdepolarizations and ventricular tachyarrhythmias despite significant QT prolongation.
  
  
  CONCLUSIONS
  Ranolazine decreases inducibility of VF in the presence of a significant increase in postrepolarization refractoriness. This antiarrhythmic effect in the intact heart is preserved in CHF and is not associated with drug-induced proarrhythmia.
authors.affiliation: Division of Electrophysiology, Department of Cardiovascular Medicine, Hospital of Westfälische Wilhelms-University, University of Münster, Münster, Germany.
authors.forename: Gerrit
authors.initials: G
authors.lastname: Frommeyer
authors.forename: Sridharan
authors.initials: S
authors.lastname: Rajamani
authors.forename: Fabian
authors.initials: F
authors.lastname: Grundmann
authors.forename: Jörg
authors.initials: J
authors.lastname: Stypmann
authors.forename: Nani
authors.initials: N
authors.lastname: Osada
authors.forename: Günter
authors.initials: G
authors.lastname: Breithardt
authors.forename: Luiz
authors.initials: L
authors.lastname: Belardinelli
authors.forename: Lars
authors.initials: L
authors.lastname: Eckardt
authors.forename: Peter
authors.initials: P
authors.lastname: Milberg
mesh_terms: D000083:Acetanilides / Q000494:pharmacology*; D000200:Action Potentials / Q000187:drug effects; D000818:Animals; D000889:Anti-Arrhythmia Agents / Q000494:pharmacology*; D004195:Disease Models, Animal; D004562:Electrocardiography; D006333:Heart Failure / Q000188:drug therapy; D010879:Piperazines / Q000494:pharmacology*; D011817:Rabbits; D000069458:Ranolazine; D012032:Refractory Period, Electrophysiological / Q000187:drug effects*; D013015:Sotalol / Q000494:pharmacology; D014693:Ventricular Fibrillation / Q000517:prevention & control*
chemical_list: D000083:Acetanilides; D000889:Anti-Arrhythmia Agents; D010879:Piperazines; D013015:Sotalol; D000069458:Ranolazine