title: Nadolol decreases the incidence and severity of ventricular arrhythmias during exercise stress testing compared with β1-selective β-blockers in patients with catecholaminergic polymorphic ventricular tachycardia.
abstract: BACKGROUND
  Catecholaminergic polymorphic ventricular tachycardia (CPVT) is an inheritable cardiac disease predisposing to malignant ventricular arrhythmias.
  
  
  OBJECTIVE
  We aimed to explore the incidence and severity of ventricular arrhythmias in patients with CPVT before the initiation of β-blocker treatment, when treated with β1-selective β-blockers, and when treated with nadolol.
  
  
  METHODS
  In this study, 34 patients with CPVT were included (mean age 34 ± 19 years; 15 (44%) women; 30 (88%) ryanodine receptor 2 variant positive). We performed 3 bicycle exercise stress tests in each patient: (1) before the initiation of β-blocker treatment, (2) after >6 weeks of treatment with β1-selective β-blockers and (3) after >6 weeks of treatment with nadolol. We recorded resting and maximum heart rates and the most severe ventricular arrhythmia occurring. Severity of arrhythmias was scored as 1 point for no arrhythmias or only single ventricular extrasystoles, 2 points for >10 ventricular extrasystoles per minute or bigeminy, 3 points for couplets, and 4 points for nonsustained ventricular tachycardia or sustained ventricular tachycardia.
  
  
  RESULTS
  Resting heart rate was similar during treatment with nadolol and β1-selective β-blockers (54 ± 10 beats/min vs 56 ± 14 beats/min; P = .50), while maximum heart rate was lower during treatment with nadolol compared with β1-selective β-blockers (122 ± 21 beats/min vs 139 ± 24 beats/min; P = .001). Arrhythmias during exercise stress testing were less severe during treatment with nadolol compared with during treatment with β1-selective β-blockers (arrhythmic score 1.6 ± 0.9 vs 2.5 ± 0.8; P < .001) and before the initiation of β-blocker treatment (arrhythmic score 1.6 ± 0.9 vs 2.7 ± 0.9; P = .001); however, no differences were observed during treatment with β1-selective β-blockers compared with before the initiation of β-blocker treatment (arrhythmic score 2.5 ± 0.8 vs 2.7 ± 0.9; P = .46).
  
  
  CONCLUSIONS
  The incidence and severity of ventricular arrhythmias decreased during treatment with nadolol compared with during treatment with β1-selective β-blockers. β1-Selective β-blockers did not change the occurrence or severity of arrhythmias compared with no medication.
authors.affiliation: Department of Cardiology, Oslo University Hospital, Rikshospitalet, Oslo, Norway; Center for Cardiological Innovation, Oslo University Hospital, Rikshospitalet, Oslo, Norway; University of Oslo, Oslo, Norway.
authors.forename: Ida S
authors.initials: IS
authors.lastname: Leren
authors.affiliation: Department of Cardiology, Oslo University Hospital, Rikshospitalet, Oslo, Norway; Center for Cardiological Innovation, Oslo University Hospital, Rikshospitalet, Oslo, Norway; University of Oslo, Oslo, Norway,; Institute for Surgical Research, Oslo University Hospital, Rikshospitalet, Oslo, Norway.
authors.forename: Jørg
authors.initials: J
authors.lastname: Saberniak
authors.affiliation: University of Oslo, Oslo, Norway.
authors.forename: Eman
authors.initials: E
authors.lastname: Majid
authors.affiliation: Department of Cardiology, Oslo University Hospital, Rikshospitalet, Oslo, Norway; Center for Cardiological Innovation, Oslo University Hospital, Rikshospitalet, Oslo, Norway; University of Oslo, Oslo, Norway,; Institute for Surgical Research, Oslo University Hospital, Rikshospitalet, Oslo, Norway.
authors.forename: Trine F
authors.initials: TF
authors.lastname: Haland
authors.affiliation: Department of Cardiology, Oslo University Hospital, Rikshospitalet, Oslo, Norway; Center for Cardiological Innovation, Oslo University Hospital, Rikshospitalet, Oslo, Norway; University of Oslo, Oslo, Norway,; Institute for Surgical Research, Oslo University Hospital, Rikshospitalet, Oslo, Norway.
authors.forename: Thor
authors.initials: T
authors.lastname: Edvardsen
authors.affiliation: Department of Cardiology, Oslo University Hospital, Rikshospitalet, Oslo, Norway; Center for Cardiological Innovation, Oslo University Hospital, Rikshospitalet, Oslo, Norway; University of Oslo, Oslo, Norway,; Institute for Surgical Research, Oslo University Hospital, Rikshospitalet, Oslo, Norway. Electronic address: Kristina.Haugaa@rr-research.no.
authors.forename: Kristina H
authors.initials: KH
authors.lastname: Haugaa
mesh_terms: D000293:Adolescent; D000319:Adrenergic beta-Antagonists / Q000008:administration & dosage / Q000009:adverse effects; D000328:Adult; D016903:Drug Monitoring; D004562:Electrocardiography / Q000379:methods; D005080:Exercise Test / Q000009:adverse effects / Q000379:methods; D005260:Female; D006339:Heart Rate / Q000187:drug effects; D006801:Humans; D015994:Incidence; D008297:Male; D008875:Middle Aged; D009248:Nadolol / Q000008:administration & dosage / Q000009:adverse effects; D009664:Norway; D019837:Ryanodine Receptor Calcium Release Channel / Q000378:metabolism; D012720:Severity of Illness Index; D017180:Tachycardia, Ventricular / Q000175:diagnosis / Q000188:drug therapy / Q000453:epidemiology / Q000209:etiology / Q000517:prevention & control; D016896:Treatment Outcome; D000098850:Polymorphic Catecholaminergic Ventricular Tachycardia
chemical_list: D000319:Adrenergic beta-Antagonists; D019837:Ryanodine Receptor Calcium Release Channel; D009248:Nadolol
keywords: Catecholaminergic polymorphic ventricular tachycardia; Exercise stress test; Ventricular arrhythmias; β-Blocker treatment