Risk stratification in short QT syndrome: Findings from a pooled analysis.

BACKGROUND

In long QT syndrome, longer QT intervals indicate increased arrhythmic risk, and a rate-corrected QT interval (QTc) of ≥500 ms denotes high risk. Establishing similar associations in short QT syndrome (SQTS) remains elusive.

OBJECTIVE

This study aimed to demonstrate that shorter QT intervals denote a higher risk of malignant arrhythmias in SQTS and to define the "high-risk" QTc value in SQTS.

METHODS

Pooled analysis of patients treated in our institutions or those reported in the literature revealed 162 patients with SQTS and known symptomatic status; 57 of them (35.2%) had arrhythmic symptoms (sudden death, cardiac arrest, or malignant syncope).

RESULTS

There was a significant inverse association between the QTc and arrhythmic symptoms (with a median QTc of 315.0 ms [interquartile range 300.5-338.0] among symptomatic patients vs 330.0 ms [interquartile range 312.5-355.0] among asymptomatic patients; P = .0023). Receiver operator characteristics analysis showed that shorter QTc values were associated with a higher risk (area under the curve 0.64 ± 0.04; P = .0024). When patients were grouped by QTc range, most of those with a QTc of ≤320 ms had malignant arrhythmic symptoms, whereas the reverse was true for those with a QTc of ≥320 ms. Male patients were overrepresented in the SQTS cohort and more so in the subgroup with malignant symptoms.

CONCLUSION

This pooled analysis of patients with SQTS demonstrates that, among patients with congenital SQTS, a shorter QTc is associated with a higher risk of malignant ventricular arrhythmias. A QTc shorter than 320 ms correlates with a higher arrhythmic risk. Men seem to be at higher risk.