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. 2017 May 31;6(6):e005684.
doi: 10.1161/JAHA.117.005684.

Shortening of the Short Refractory Periods in Short QT Syndrome

Anne Rollin  1 , Estelle Gandjbakhch  2 , Carla Giustetto  3 , Chiara Scrocco  3 , Carole Fourcade  1 , Benjamin Monteil  1 , Pierre Mondoly  1 , Christelle Cardin  1 , Carole Maupain  2 , Fiorenzo Gaita  3 , Philippe Maury  4
Affiliations

Shortening of the Short Refractory Periods in Short QT Syndrome

Anne Rollin et al. J Am Heart Assoc. .

Abstract

Background: Diagnosis of short QT syndrome (SQTS) remains difficult in case of borderline QT values as often found in normal populations. Whether some shortening of refractory periods (RP) may help in differentiating SQTS from normal subjects is unknown.

Methods and results: Atrial and right ventricular RP at the apex and right ventricular outflow tract as determined during standard electrophysiological study were compared between 16 SQTS patients (QTc 324±24 ms) and 15 controls with similar clinical characteristics (QTc 417±32 ms). Atrial RP were significantly shorter in SQTS compared with controls at 600- and 500-ms basic cycle lengths. Baseline ventricular RP were significantly shorter in SQTS patients than in controls, both at the apex and right ventricular outflow tract and for any cycle length. Differences remained significant for RP of any subsequent extrastimulus at any cycle length and any pacing site. A cut-off value of baseline RP <200 ms at the right ventricular outflow tract either at 600- or 500-ms cycle length had a sensitivity of 86% and a specificity of 100% for the diagnosis of SQTS.

Conclusions: Patients with SQTS have shorter ventricular RP than controls, both at baseline during various cycle lengths and after premature extrastimuli. A cut-off value of 200 ms at the right ventricular outflow tract during 600- and 500-ms basic cycle length may help in detecting true SQTS from normal subjects with borderline QT values.

Keywords: QT interval electrocardiography; refractory periods; risk stratification; short QT syndrome; sudden death.

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Figures

Figure 1
Figure 1
Protocol of programmed ventricular stimulation used for the determination of refractory periods (RP). S indicates stimulus.
Figure 2
Figure 2
Atrial refractory periods at 600‐, 500‐, and 400‐ms cycle lengths in SQTS (light gray) and controls (shaded). *indicates statistically significant difference; SQTS, short QT syndrome.
Figure 3
Figure 3
Right ventricular refractory periods at the right ventricular apex (RV apex) and right ventricular outflow tract (RVOT) at 600‐, 500‐, and 400‐ms cycle lengths in SQTS (light gray) and controls (shaded) *indicates statistically significant difference; SQTS, short QT syndrome.
Figure 4
Figure 4
Right ventricular refractory periods for S2 and S3 extrastimuli at the right ventricular apex (RA apex) and right ventricular outflow tract (RVOT) at 600‐, 500‐, and 400‐ms cycle lengths in SQTS (light gray) and controls (shaded). *indicates statistically significant difference; SQTS, short QT syndrome.
Figure 5
Figure 5
Example of very short ventricular refractory periods (RP) after S2 stimulus in a patient with SQTS: after S2 extrastimulus, the S3 extrastimulus leads to ventricular capture for a coupling interval as short as 130 ms before reaching local RP at a coupling interval of 110 ms. S indicates stimulus; SQTS, short QT syndrome.
Figure 6
Figure 6
Plot of ventricular refractory periods (RP) against S1, S2, and S3 beats, at the right ventricular apex (RA apex) and right ventricular outflow tract (RVOT), at 600‐, 500‐, and 400‐ms cycle lengths, both in SQTS and controls, showing decrease in RP for shorter basic cycle length or for additional short‐coupled extrastimuli. SQTS indicates short QT syndrome.
Figure 7
Figure 7
Distribution of SQTS patients and controls according to a 200‐ms cut‐off value of baseline ventricular refractory periods (RP) at the right ventricular outflow tract (RVOT) at 600‐ or 500‐ms cycle length. None of the controls showed RP <200 ms while almost none of the SQTS displayed RP >200 ms. SQTS indicates short QT syndrome.
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References

    1. Gussak I, Brugada P, Brugada J, Wright RS, Kopecky SL, Chaitman BR, Bjerregaard P. Idiopathic short QT interval: a new clinical syndrome? Cardiology. 2000;94:99–102. - PubMed
    1. Priori SG, Wilde AA, Horie M, Cho Y, Behr ER, Berul C, Blom N, Brugada J, Chiang CE, Huikuri H, Kannankeril P, Krahn A, Leenhardt A, Moss A, Schwartz PJ, Shimizu W, Tomaselli G, Tracy C. HRS/EHRA/APHRS expert consensus statement on the diagnosis and management of patients with inherited primary arrhythmia syndromes. Heart Rhythm. 2013;10:1932–1963. - PubMed
    1. Priori SG, Blomström‐Lundqvist C, Mazzanti A, Blom N, Borggrefe M, Camm J, Elliott PM, Fitzsimons D, Hatala R, Hindricks G, Kirchhof P, Kjeldsen K, Kuck KH, Hernandez‐Madrid A, Nikolaou N, Norekvål TM, Spaulding C, Van Veldhuisen DJ. 2015 ESC guidelines for the management of patients with ventricular arrhythmias and the prevention of sudden cardiac death. Eur Heart J. 2015;36:2793–2867. - PubMed
    1. Gollob MH, Redpath CJ, Roberts JD. The short QT syndrome: proposed diagnostic criteria. J Am Coll Cardiol. 2011;57:802–812. - PubMed
    1. Giustetto C, Schimpf R, Mazzanti A, Scrocco C, Maury P, Anttonen O, Probst V, Blanc JJ, Sbragia P, Dalmasso P, Borggrefe M, Gaita F. Long‐term follow‐up of patients with short QT syndrome. J Am Coll Cardiol. 2011;58:587–595. - PubMed

Supplementary concepts