SQTS: Difference between revisions

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-There is controversy whether short QT intervals are associated with sudden death. One trial found QTc intervals < 300ms to be associated with sudden death.<cite>Gaita</cite> However, a recent Finnish study in a random selection of healthy subjects (n=10 822) did not find an increased incidence of sudden death in patients with short QTc intervals. They defined QTc < 320ms as 'very short' and QTc < 340ms as 'short'. In total, 15 deaths occured in the group with QTc <340ms, with only one possible sudden death (cause of death unknown). They used Friderica's method for QTc correction: [[Image:Fridericia.png|100px]].<cite>Fridericia</cite> They conclude that the ECG is not a good screening tool to find patients with a short QTc interval at risk of sudden death.<cite>Anttonen</cite>
+<i>Auteur: Louise R.A. Olde Nordkamp</i>
-[[File:Sqts.svg|thumb|Precordial ECG tracings of a patient with SQTS]]
+<i>Supervisor: Arthur A.M. Wilde</i>
+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==
+[[Image:ShortQT_syndrome_patient.png|thumb|right]]
+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==
+[[Image:Bazett.png|thumb|left]]
+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==
+[[Image:ShortQT_syndrome_mechanism.png|thumb|left]]
+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.
+==Treatment==
+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
 == References ==
 <biblio>
-#bazett Bazett HC. ''An analysis of the time-relations of electrocardiograms''. Heart 1920;7:353-370.
+#Giustetto pmid=16926178
-#Lepeschkin pmid=14954534
+#Giustetto2 pmid=21798421
-#Gaita pmid=12925462
+#Patel pmid=20716721
-#Anttonen pmid=17679619
-#Fridericia Fridericia LS. ''Die Systolendauer im Elektrokardiogramm bei normalen
-Menschen und bei Herzkranken''. Acta Med Scand. 1920;53:469–486.
 </biblio>