Follow-up with exercise test of effort-induced ventricular arrhythmias linked to ryanodine receptor type 2 gene mutations.
The aim of this study was to assess exercise test results and efficacy of therapy with a β blocker (acebutolol) in ryanodine receptor type 2 (RyR2) mutation carriers with documented ventricular arrhythmias (VAs) and long-term follow-up. Twenty RyR2 mutation carriers belonging to 8 families and regularly followed at our center were analyzed using a study protocol involving electrocardiography, exercise tests off and on β-blocker therapy, 2-dimensional echocardiography, and signal-averaged electrocardiography. Off-therapy exercise testing triggered the onset of VAs at different heart rates (mean 132 ± 13 beats/min) with various patterns that worsened while exercising and disappeared immediately after stopping. The most severe VAs detected were nonsustained ventricular tachycardia in 35% and ventricular couplets in 35%. In the remaining subjects single ventricular premature beats were recorded. In 15% of patients single monomorphic ventricular premature beats were detected and identified to be linked to RyR2 mutations owing to the presence of sudden deaths of their family members and subsequent family screening. Acebutolol made the VAs disappear completely in 20% of subjects and decreased their complexity in 50%, whereas it did not change VAs appreciably in 30% of patients with less complex VAs. After 11 ± 8 years of follow-up 2 patients developed syncope. In conclusion, exercise testing was a fundamental tool for assessing the clinical phenotype and efficacy of therapy in RyR2 mutation carriers and therapy with acebutolol led in most subjects to a decreased complexity of the arrhythmic pattern or to complete suppression.
Department of Cardiac, Thoracic, and Vascular Sciences, University of Padua, Italy. steriotis@hotmail.com
Alexandros Klavdios
AK
Steriotis
Andrea
A
Nava
Alessandra
A
Rampazzo
Cristina
C
Basso
Gaetano
G
Thiene
Luciano
L
Daliento
Antonio Franco
AF
Folino
Ilaria
I
Rigato
Elisa
E
Mazzotti
Giorgia
G
Beffagna
Elisa
E
Carturan
Domenico
D
Corrado
Barbara
B
Bauce
D000070:Acebutolol / Q000627:therapeutic use; D000293:Adolescent; D000328:Adult; D000889:Anti-Arrhythmia Agents / Q000627:therapeutic use; D015331:Cohort Studies; D016757:Death, Sudden, Cardiac / Q000517:prevention & control; D004452:Echocardiography; D004562:Electrocardiography; D005080:Exercise Test / Q000009:adverse effects; D005190:Family; D005260:Female; D005500:Follow-Up Studies; D005819:Genetic Markers / Q000235:genetics; D005820:Genetic Testing; D006579:Heterozygote; D006801:Humans; D008297:Male; D009154:Mutation; D010375:Pedigree; D010641:Phenotype; D005082:Physical Exertion; D019837:Ryanodine Receptor Calcium Release Channel / Q000235:genetics*; D017180:Tachycardia, Ventricular / Q000175:diagnosis / Q000188:drug therapy / Q000209:etiology* / Q000235:genetics; D016896:Treatment Outcome
D000889:Anti-Arrhythmia Agents; D005819:Genetic Markers; D019837:Ryanodine Receptor Calcium Release Channel; D000070:Acebutolol