A case of pacemaker "malfunction": Should I intervene?

A 72 year old gentleman presented to us for sinus node dysfunction and was accepted for pacemaker implantation. He had significant history of paroxysmal atrial fibrillation (PAF) and typical atrial flutter. Physical examination was unremarkable. Echocardiography demonstrated normal left ventricular ejection fraction and moderate biatrial dilatation. He underwent an uneventful implantation for a dual chamber permanent pacemaker (PPM). The procedure was uncomplicated and lead parameters were normal. Post implant chest X ray showed stable leads positions. Fig. 1 shows the post implant 12 lead ECG. What is the likely diagnosis?