d o
t o r e g . c o m
Dr. Mete ALPASLAN
Short QT interval
Last update: June 2020
Short QT interval may be
congenital
or
acquired
.
About the congenital Short QT Interval Syndrome (SQTS)
This autosomal dominant disease is caused by mutations in genes encoding potassium, calcium or sodium ion channels of the cell membrane.
The patients do not necessarily have structural heart disease. Echocardiogram or coronary arteriography may be normal.
These patients may have a family history of sudden cardiac death.
Congenital SQTS is very very rare.
About the genetic alterations in SQTS
Gain-of-function mutations of potassium and loss of- function mutations of calcium and sodium channels result in an abbreviated repolarisation phase during action potential and shortening of the QT interval.
There are overlapping genes in SQTS, Long QT Syndrome (LQTS), Brugada Syndrome (BrS) and Catecholaminergic Polymorphic Ventricular Tachycardia (CPVT).
KCNH2: encodes a voltage-activated potassium channel. It is associated with SQTS type 1 and LQTS.
KCNQ1: encodes a voltage-gated potassium channel required for repolarization. It is associated with SQTS type 2 and LQTS.
KCNJ2: encodes a rectifier type potassium channel. It is associated with SQTS type 3, LQTS, CPVT.
CACNA1C: encodes an alpha-1 subunit of a voltage-dependent calcium channel. It is associated with SQTS type 4 and BrS, leading to a combined phenotype of BrS and short QT interval.
CACNB2b: encodes a subunit of a voltage-dependent calcium channel protein. It is associated with SQTS type 5 and BrS, leading to a combined phenotype of BrS and short QT interval.
CACNA2D1: encodes encodes a member of the alpha-2/delta subunit family, a protein in the voltage-dependent calcium channel complex. It is associated with SQTS type 6, LQTS and BrS.
SCN5A: encodes encodes the sodium channel protein type 5-subunit alpha which mediates the voltage-dependent sodium ion permeability of myocyte membranes. It is associated with SQTS type 7, LQTS and BrS. It may lead to a combined phenotype of BrS and short QT interval.
SLC4A3: encodes a plasma membrane anion exchange protein 3. It is associated with SQTS type 8.
Clinical manifestations of SQTS
Sudden infant death syndrome.
Paroxysmal atrial fibrillation.
Syncope.
Ventricular arrhythmias.
Sudden cardiac death.
Electrocardiographic features of SQTS
The QT interval < 320 ms (there is no universally accepted diagnostic cut-off value of short QT interval).
The QT interval fails to increase during bradycardia. This impaired QT adaptation to heart rate changes makes the correction formulas like Bazett or Fredericia inappropriate.
The ST segment is virtually absent. The QRS complex seems to connect directly to the T wave.
There may be tall and peaked T waves with narrow bases, especially in precordial leads. Tall T waves may be a problem for oversensing in SQTS patients receiving an implantable cardioverter-defibrillator (ICD) leading to inappropriate shocks.
PQ depression is reported in 81% of STQS patients. PQ depression was defined as 0.05 mV (0.5 mm) depression from the isoelectric line.
Paroxysmal atrial fibrillation episodes may be observed.
A high prevalence of early repolarization was reported in patients with SQTS.
Some patients may show combined phenotype of BrS and short QT interval.
Acquired causes of short QT interval
Digoxin
Mexiletine
Rufinamide
Hyperkalemia
Hypercalcemia
Acidosis
Hyperthermia
References
J Clin Med 2019;8. pii: E1035. doi: 10.3390/jcm8071035.
Card Electrophysiol Clin 2019;11:345-362.
Front Cardiovasc Med 2018;5:149.
Heart Rhythm 2018;15(8):1261-1267.
JACC Clin Electrophysiol 2017;3(7):727-743.
Int J Cardiol Heart Vasc 2017;18:101-103.
Circ Arrhythm Electrophysiol 2015;8(6):1460-1464.
Heart Rhythm 2014;11:1024-1030.
Arrhythm Electrophysiol Rev 2014;3(2):76-79.
J Am Coll Cardiol 2014;63(13):1300-1308.
Arrhythm Electrophysiol Rev 2014;3(2):76-79.
Pediatr Int 2014;56(5):774-776.
Cardiology 2014;128(3):236-240.
Cardiol J 2013;20(5):464-471.
Anadolu Kardiyol Derg 2012;12(3):274-275.
Heart Rhythm 2010;7:647-652.
Cardiol Rev 2009;17:300-303.
Circulation 2007;115:442-449.
CMAJ 2005;173(11):1349-1354.
Circ Res 2005;96:800-807.
J Cardiovasc Electrophysiol 2003;14:1273-1277.
ECG 1. Congenital short QT syndrome. There is almost no ST segment. Narrow-based, tall and peaked T waves are observed in chest leads. Precordial leads and leads II and aVF show PQ depression while lead aVR shows PQ elevation. Congenital short QT interval syndrome was first described by Dr. Preben Bjerregaard in 1999.
Prof Dr. Preben Bjerregaard has donated this ECG to our website.
Click here for a more detailed ECG
Click here to visit Prof Dr. Preben Bjerregaard's website on Short QT Interval Syndrome.
ECG 2a. The limb leads of a patient with short QT syndrome.
This ECG has been donated by Dr. Rainer Schimpf (rainer.schimpf@umm.de) to our website.
Click here for a more detailed ECG
ECG 2b. The chest leads of the same patient with the short QT interval syndrome.
Dr. Rainer Schimpf (rainer.schimpf@umm.de) has donated this ECG to our website.
Click here for a more detailed ECG
ECG 3. SQT3.
This ECG has been donated by Dr. Nicola Monteforte (nicola.monteforte@fsm.it) and Prof. Silvia Priori to our website.
Click here for a more detailed ECG
ECG 4a. The ECG above belongs to a 23 years-old man with congenital short QT syndrome.
It was recorded 2 months after Quinidine use for short qt interval.
This ECG was donated by Cardiologist Serhat Gunlu. All of the short QT interval ECGs donated by Dr. Serhat Gunlu belong to the members of a single family from the same city.
Click here for a more detailed ECG
ECG 4b. The compact ECG above is derived from the ECG 4a.
(It was recorded 2 months after Quinidine use for short qt interval)
This ECG was donated by Cardiologist Serhat Gunlu. All of the short QT interval ECGs donated by Dr. Serhat Gunlu belong to the members of a single family from the same city.
ECG 5a. The ECG above belongs to a different member of the same family with short QT interval syndrome.
It was recorded 2 months after Quinidine use for short qt interval.
This ECG was donated by Cardiologist Serhat Gunlu. All of the short QT interval ECGs donated by Dr. Serhat Gunlu belong to the members of a single family from the same city.
Click here for a more detailed ECG
ECG 5b. The compact ECG above is derived from the ECG 5a.
(It was recorded 2 months after Quinidine use for short qt interval)
This ECG was donated by Cardiologist Serhat Gunlu. All of the short QT interval ECGs donated by Dr. Serhat Gunlu belong to the members of a single family from the same city.
ECG 6. The ECG above belongs to a 24 years-old woman from the same family with short QT interval syndrome.
It was recorded 2 months after Quinidine use for short qt interval.
This ECG was donated by Cardiologist Serhat Gunlu. All of the short QT interval ECGs donated by Dr. Serhat Gunlu belong to the members of a single family from the same city.
Click here for a more detailed ECG
ECG 7a. The ECG above belongs to a 15 years-old girl from the same family with short QT interval syndrome.
It was recorded 2 months after Quinidine use for short qt interval.
This ECG was donated by Cardiologist Serhat Gunlu. All of the short QT interval ECGs donated by Dr. Serhat Gunlu belong to the members of a single family from the same city.
Click here for a more detailed ECG
ECG 7b. The compact ECG above is derived from the ECG 7a.
(It was recorded 2 months after Quinidine use for short qt interval)
This ECG was donated by Cardiologist Serhat Gunlu. All of the short QT interval ECGs donated by Dr. Serhat Gunlu belong to the members of a single family from the same city.
Last update: June 2020
Short QT interval may be
congenital
or
acquired
.
About the congenital Short QT Interval Syndrome (SQTS)
This autosomal dominant disease is caused by mutations in genes encoding potassium, calcium or sodium ion channels of the cell membrane.
The patients do not necessarily have structural heart disease. Echocardiogram or coronary arteriography may be normal.
These patients may have a family history of sudden cardiac death.
Congenital SQTS is very very rare.
About the genetic alterations in SQTS
Gain-of-function mutations of potassium and loss of- function mutations of calcium and sodium channels result in an abbreviated repolarisation phase during action potential and shortening of the QT interval.
There are overlapping genes in SQTS, Long QT Syndrome (LQTS), Brugada Syndrome (BrS) and Catecholaminergic Polymorphic Ventricular Tachycardia (CPVT).
KCNH2: encodes a voltage-activated potassium channel. It is associated with SQTS type 1 and LQTS.
KCNQ1: encodes a voltage-gated potassium channel required for repolarization. It is associated with SQTS type 2 and LQTS.
KCNJ2: encodes a rectifier type potassium channel. It is associated with SQTS type 3, LQTS, CPVT.
CACNA1C: encodes an alpha-1 subunit of a voltage-dependent calcium channel. It is associated with SQTS type 4 and BrS, leading to a combined phenotype of BrS and short QT interval.
CACNB2b: encodes a subunit of a voltage-dependent calcium channel protein. It is associated with SQTS type 5 and BrS, leading to a combined phenotype of BrS and short QT interval.
CACNA2D1: encodes encodes a member of the alpha-2/delta subunit family, a protein in the voltage-dependent calcium channel complex. It is associated with SQTS type 6, LQTS and BrS.
SCN5A: encodes encodes the sodium channel protein type 5-subunit alpha which mediates the voltage-dependent sodium ion permeability of myocyte membranes. It is associated with SQTS type 7, LQTS and BrS. It may lead to a combined phenotype of BrS and short QT interval.
SLC4A3: encodes a plasma membrane anion exchange protein 3. It is associated with SQTS type 8.
Clinical manifestations of SQTS
Sudden infant death syndrome.
Paroxysmal atrial fibrillation.
Syncope.
Ventricular arrhythmias.
Sudden cardiac death.
Electrocardiographic features of SQTS
The QT interval < 320 ms (there is no universally accepted diagnostic cut-off value of short QT interval).
The QT interval fails to increase during bradycardia. This impaired QT adaptation to heart rate changes makes the correction formulas like Bazett or Fredericia inappropriate.
The ST segment is virtually absent. The QRS complex seems to connect directly to the T wave.
There may be tall and peaked T waves with narrow bases, especially in precordial leads. Tall T waves may be a problem for oversensing in SQTS patients receiving an implantable cardioverter-defibrillator (ICD) leading to inappropriate shocks.
PQ depression is reported in 81% of STQS patients. PQ depression was defined as 0.05 mV (0.5 mm) depression from the isoelectric line.
Paroxysmal atrial fibrillation episodes may be observed.
A high prevalence of early repolarization was reported in patients with SQTS.
Some patients may show combined phenotype of BrS and short QT interval.
Acquired causes of short QT interval
Digoxin
Mexiletine
Rufinamide
Hyperkalemia
Hypercalcemia
Acidosis
Hyperthermia
References
J Clin Med 2019;8. pii: E1035. doi: 10.3390/jcm8071035.
Card Electrophysiol Clin 2019;11:345-362.
Front Cardiovasc Med 2018;5:149.
Heart Rhythm 2018;15(8):1261-1267.
JACC Clin Electrophysiol 2017;3(7):727-743.
Int J Cardiol Heart Vasc 2017;18:101-103.
Circ Arrhythm Electrophysiol 2015;8(6):1460-1464.
Heart Rhythm 2014;11:1024-1030.
Arrhythm Electrophysiol Rev 2014;3(2):76-79.
J Am Coll Cardiol 2014;63(13):1300-1308.
Arrhythm Electrophysiol Rev 2014;3(2):76-79.
Pediatr Int 2014;56(5):774-776.
Cardiology 2014;128(3):236-240.
Cardiol J 2013;20(5):464-471.
Anadolu Kardiyol Derg 2012;12(3):274-275.
Heart Rhythm 2010;7:647-652.
Cardiol Rev 2009;17:300-303.
Circulation 2007;115:442-449.
CMAJ 2005;173(11):1349-1354.
Circ Res 2005;96:800-807.
J Cardiovasc Electrophysiol 2003;14:1273-1277.
ECG 1. Congenital short QT syndrome. There is almost no ST segment. Narrow-based, tall and peaked T waves are observed in chest leads. Precordial leads and leads II and aVF show PQ depression while lead aVR shows PQ elevation. Congenital short QT interval syndrome was first described by Dr. Preben Bjerregaard in 1999.
Prof Dr. Preben Bjerregaard has donated this ECG to our website.
Click here for a more detailed ECG
Click here to visit Prof Dr. Preben Bjerregaard's website on Short QT Interval Syndrome.
ECG 2a. The limb leads of a patient with short QT syndrome.
This ECG has been donated by Dr. Rainer Schimpf (rainer.schimpf@umm.de) to our website.
Click here for a more detailed ECG
ECG 2b. The chest leads of the same patient with the short QT interval syndrome.
Dr. Rainer Schimpf (rainer.schimpf@umm.de) has donated this ECG to our website.
Click here for a more detailed ECG
ECG 3. SQT3.
This ECG has been donated by Dr. Nicola Monteforte (nicola.monteforte@fsm.it) and Prof. Silvia Priori to our website.
Click here for a more detailed ECG
ECG 4a. The ECG above belongs to a 23 years-old man with congenital short QT syndrome.
It was recorded 2 months after Quinidine use for short qt interval.
This ECG was donated by Cardiologist Serhat Gunlu. All of the short QT interval ECGs donated by Dr. Serhat Gunlu belong to the members of a single family from the same city.
Click here for a more detailed ECG
ECG 4b. The compact ECG above is derived from the ECG 4a.
(It was recorded 2 months after Quinidine use for short qt interval)
This ECG was donated by Cardiologist Serhat Gunlu. All of the short QT interval ECGs donated by Dr. Serhat Gunlu belong to the members of a single family from the same city.
ECG 5a. The ECG above belongs to a different member of the same family with short QT interval syndrome.
It was recorded 2 months after Quinidine use for short qt interval.
This ECG was donated by Cardiologist Serhat Gunlu. All of the short QT interval ECGs donated by Dr. Serhat Gunlu belong to the members of a single family from the same city.
Click here for a more detailed ECG
ECG 5b. The compact ECG above is derived from the ECG 5a.
(It was recorded 2 months after Quinidine use for short qt interval)
This ECG was donated by Cardiologist Serhat Gunlu. All of the short QT interval ECGs donated by Dr. Serhat Gunlu belong to the members of a single family from the same city.
ECG 6. The ECG above belongs to a 24 years-old woman from the same family with short QT interval syndrome.
It was recorded 2 months after Quinidine use for short qt interval.
This ECG was donated by Cardiologist Serhat Gunlu. All of the short QT interval ECGs donated by Dr. Serhat Gunlu belong to the members of a single family from the same city.
Click here for a more detailed ECG
ECG 7a. The ECG above belongs to a 15 years-old girl from the same family with short QT interval syndrome.
It was recorded 2 months after Quinidine use for short qt interval.
This ECG was donated by Cardiologist Serhat Gunlu. All of the short QT interval ECGs donated by Dr. Serhat Gunlu belong to the members of a single family from the same city.
Click here for a more detailed ECG
ECG 7b. The compact ECG above is derived from the ECG 7a.
(It was recorded 2 months after Quinidine use for short qt interval)
This ECG was donated by Cardiologist Serhat Gunlu. All of the short QT interval ECGs donated by Dr. Serhat Gunlu belong to the members of a single family from the same city.