Short QT Interval Syndromes By L Brent Mitchell, MD, Libin Cardiovascular Institute of Alberta, University of Calgary Reviewed / Revised Jan 2023 View Patient Education Diagnosis Treatment The short QT interval syndromes (SQTS) are extremely rare congenital or very rarely acquired disorders of cardiac ion channel function or regulation that shorten ventricular myocyte action potential duration as reflected by shortening of the rate-corrected QT interval on the ECG.