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.