Prolonged QTc due to hypocalcemia

A middle-aged pt non-compliant DM II, CKD, hypertensive is being managed as  hyperosmolar hyperglycemic state (formerly called HONK) with glucose in the 800's, Na 113, K 3.5, BUN 65, creatinine 6.1.

What is the ECG telling us and probable cause of the ECG finding/s?

The 12L is sinus rhythm with prolonged QTc (> 500 ms). Additional labs revealed phosphorus 5.2 (high), calcium 5.8 (corrected - 6.2)(low), albumin 3.4, troponin negative, magnesium 1.9. (normal). So, the cause of the prolonged QT/QTc was hypocalcemia due to renal failure.

The blood sugar was eventually controlled and the calcium was corrected. Pt was eventually discharged a few days and advised for close ff-up.

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