Short QT syndrome (SQTS) is a condition that can cause a disruption of the heart’s normal rhythm (arrhythmia). In people with this condition, the heart (cardiac) muscle takes less time than usual to recover between beats. The term “short QT” refers to a specific pattern of heart activity that is detected with a normal electrocardiogram (ECG). In people with this condition, the part of the heartbeat known as the QT interval is abnormally short.
SQTS is an inherited disorder in which movement of ions through protein channels, or doorways, in the cell membrane are altered. In contrast to long QT syndrome, this alteration results in a marked shortening of the ventricular action potentials (APD) and shortened QT intervals, predisposing affected individuals to a risk of atrial and ventricular arrhythmias.
The researchers at the Masonic Medical Research Laboratory (MMRL) succeeded in identifying the first gene responsible for SQTS, named (KCNH2). Channels made with the KCNH2 protein (also known as hERG1) are involved in recharging the cardiac muscle after each heartbeat to maintain a regular rhythm.
Since first reported in 2000, significant progress has been made in defining the genetic and cellular basis of SQTS as well as in therapeutic approaches to treating this syndrome. SQTS is a genetically variable disease with six different genes encoding various cardiac ion channels thus far identified. The scientific studies have been promising, and with additional clinical cases, more individual patient specific treatment options are on the horizon.
One such treatment, pioneered by the researches at the MMRL, has been the utilization of a drug (quinidine), to regulate the heart rhythm. Quinidine has been proven to be useful in reversing the ECG defect in patients with SQTS, thus a potential treatment for patients diagnosed with this genetic mutation.