From Textbook of Cardiology
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Auteur: Louise R.A. Olde Nordkamp Supervisor: Arthur A.M. Wilde

The short QT syndrome is a very rare syndrome characterized by an abnormally short QT interval and increased risk of ventricular fibrillation and cardiac death.

Clinical diagnosis

ShortQT syndrome patient.png

The diagnosis is based on the presence a short QT interval, in which the upper limit is mostly set on 330 ms. Males are more often affected than women. A history of cardiac arrest is present in one-third. Patients are at risk for both atrial arrhythmias (AF) and ventricular arrhythmias (VT/VF).

Physical examination

Patients can present with symptoms of arrhythmias:

  • Out-of-hospital-cardiac-arrest
  • Syncope, pre-syncope (weakness, lightheadedness, dizziness)

ECG tests


The ECG demonstrates a corrected QT interval significantly below the limit of normal (<330 ms). Additionally, notable ECG findings are the presence of a sharp T-wave beginning at the end of the QRS complex, preceded by a brief or absent ST-segment. Exercise electrocardiographic studies in SQTS patients also characteristically reveal a non-physiologic lack of QT shortening at increased heart rates.

Genetic diagnosis

ShortQT syndrome mechanism.png

In a quarter of the patients a mutation is found, predominantly in the KCNH2 gene (SQTS1). This gain-of-function mutation causes an increase in the potassium efflux and, subsequently, to a decrease of the myocyte refractory period. Mutations in the KCNQ1, KCNJ2 and possibly CACNxxx genes are also associated with the SQTS.

Risk Stratification

Risk stratification in SQTS is still ill-defined and should be done by a specialized cardio-genetic cardiologist.


Hydroquinidine is suggested for normalization of the QT interval in patients with a KCNH2 mutation. ICD therapy is advised in SQTS patients for secondary prevention of sudden cardiac death and could be considered


Error fetching PMID 16926178:
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  1. Error fetching PMID 16926178: [Giustetto]
  2. Error fetching PMID 21798421: [Giustetto2]
  3. Error fetching PMID 20716721: [Patel]

All Medline abstracts: PubMed | HubMed