LQTS Schwartz Score
Assesses the diagnostic probability of congenital long QT syndrome using ECG, clinical, family-history and genetic findings.
Before scoring
ECG findings should be assessed in the absence of drugs, electrolyte abnormalities or other disorders known to prolong the QT interval. Resting QTc should be calculated with the Bazett formula.
Diagnostic variables
Select applicable findings
Resting QTc
Select only one resting QTc category.
Additional ECG findings
Select each independent finding that applies.
Syncope
Select only the highest applicable syncope category.
Clinical history
Select the finding if present.
Family history
The same family member should not be used for both family-history criteria.
Genetic finding
Use only a clinically classified pathogenic or likely pathogenic variant.
Interpretation
Low probability
≤1 point
Low clinical probability of LQTS.
Intermediate probability
1.5–3 points
Further clinical assessment may be required.
Clinical diagnosis supported
>3 points
Supports LQTS diagnosis when secondary causes are absent.
Clinical limitations
This is a diagnostic support score and does not predict an individual patient's future arrhythmic-event risk.
Acquired QT prolongation from medication, electrolyte disturbance, bradyarrhythmia or systemic disease should be excluded before interpreting the score.
A pathogenic LQTS-associated genetic variant can establish the diagnosis even when the resting QTc is normal.
Management decisions require specialist assessment, genotype interpretation and individualized risk evaluation.
References
Schwartz PJ, Crotti L, Insolia R. Long-QT syndrome: from genetics to management. Circ Arrhythm Electrophysiol. 2012 Aug 1;5(4):868-77. doi: 10.1161/CIRCEP.111.962019. Erratum in: Circ Arrhythm Electrophysiol. 2012 Dec;5(6):e119-20. PMID: 22895603; PMCID: PMC3461497.
Zeppenfeld K, Tfelt-Hansen J, de Riva M, Winkel BG, Behr ER, Blom NA, Charron P, Corrado D, Dagres N, de Chillou C, Eckardt L, Friede T, Haugaa KH, Hocini M, Lambiase PD, Marijon E, Merino JL, Peichl P, Priori SG, Reichlin T, Schulz-Menger J, Sticherling C, Tzeis S, Verstrael A, Volterrani M; ESC Scientific Document Group. 2022 ESC Guidelines for the management of patients with ventricular arrhythmias and the prevention of sudden cardiac death. Eur Heart J. 2022 Oct 21;43(40):3997-4126. doi: 10.1093/eurheartj/ehac262. PMID: 36017572.
This calculator provides clinical decision support and does not replace expert ECG review or inherited-arrhythmia consultation.