I have been taking concor 2.5 mg for my heartbeat since 2-3 months as prescribed for my myocardial bridge in LAD. I had my holter 15 days back which has sinus tachycardia and otherwise normal but Max QTC was 536 when my HR was 124. Couple of days back I had an ECG which was normal but my QTC was 463. Today morning when I was resting my HR was around 55-60 though there were no difficulties as such but I felt panicked so I went for ECG. I had 2 ECGs in the span of 15 mins. First ECG has QTC 310 and second ECG has QTC 432. Please tell me if both the ECGs are normal? Why fluctuating QTC ? Is it okay to have resting HR of 55-60 even when I'm a patient of sinus tachycardia?