This scared me at first

[FL_Medic]

Post-menopausal female with SOB. Always consider AMI. I can't really determine the exact width of the QRS on these strips but they look wide. You can still consider AMI with LBBB. Whether it be a new BBB, or if it meets Sgarbossa's criteria.

V1, V2, V3 appear to have st-elevation. There also appears to be st-depression in some other leads. The rate could be skewing the perception though. This rate is almost 150, was she hypotensive? Did she have a fever or other signs of dehydration? Cardiac Hx? I would treat this rate if it didn't present as a compensatory tachycardia. Without S/S of chronic respiratory disorder I would bet that the rate is causing the dyspnea.

If you're not sure if this is compensatory, treat with a fluid bolus and watch the rate. True SVT will stay extremely regular and at about the same rate. Some will say this can't be SVT because of the p-waves, but at a rate of 150, an 86 y/o F will not be able to withstand this rate forever anyhow.

This is as Fiz stated a regular rhythm. Call it SVT or Sinus Tach. Treat with Vagal maneuvers. If refractory, try some Adenocard. Still refractory, C+ Channel blockers.