• Circ Arrhythm Electrophysiol · Jun 2011

    Comparative Study

    SERCA2a gene transfer decreases sarcoplasmic reticulum calcium leak and reduces ventricular arrhythmias in a model of chronic heart failure.

    • Alexander R Lyon, Mark L Bannister, Tom Collins, Emma Pearce, Amir H Sepehripour, Sukhpreet S Dubb, Edwin Garcia, Peter O'Gara, Lifan Liang, Erik Kohlbrenner, Roger J Hajjar, Nicholas S Peters, Philip A Poole-Wilson, Ken T Macleod, and Sian E Harding.
    • National Heart and Lung Institute, Imperial College, London, United Kingdom. a.lyon@ic.ac.uk
    • Circ Arrhythm Electrophysiol. 2011 Jun 1;4(3):362-72.

    BackgroundSarcoplasmic reticulum calcium ATPase 2a (SERCA2a) gene therapy improves mechanical function in heart failure and is under evaluation in a clinical trial. A critical question is whether SERCA2a gene therapy predisposes to increased sarcoplasmic reticulum calcium (SR Ca(2+)) leak, cellular triggered activity, and ventricular arrhythmias in the failing heart.Methods And ResultsWe studied the influence of SERCA2a gene therapy on ventricular arrhythmogenesis in a rat chronic heart failure model. ECG telemetry studies revealed a significant antiarrhythmic effect of SERCA2a gene therapy with reduction of both spontaneous and catecholamine-induced arrhythmias in vivo. SERCA2a gene therapy also reduced susceptibility to reentry arrhythmias in ex vivo programmed electrical stimulation studies. Subcellular Ca(2+) homeostasis and spontaneous SR Ca(2+) leak characteristics were measured in failing cardiomyocytes transfected in vivo with a novel AAV9.SERCA2a vector. SR Ca(2+) leak was reduced after SERCA2a gene therapy, with reversal of the greater spark mass observed in the failing myocytes, despite normalization of SR Ca(2+) load. SERCA2a reduced ryanodine receptor phosphorylation, thereby resetting SR Ca(2+) leak threshold, leading to reduced triggered activity in vitro. Both indirect effects of reverse remodeling and direct SERCA2a effects appear to underlie the antiarrhythmic action.ConclusionsSERCA2a gene therapy stabilizes SR Ca(2+) load, reduces ryanodine receptor phosphorylation and decreases SR Ca(2+) leak, and reduces cellular triggered activity in vitro and spontaneous and catecholamine-induced ventricular arrhythmias in vivo in failing hearts. SERCA2a gene therapy did not therefore predispose to arrhythmias and may represent a novel antiarrhythmic strategy in heart failure.

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