Novel insights in the natural history of Short QT Syndrome

OBJECTIVES: This study intends to gain further insights into: the natural history, the yield of familial and genetic screening and the arrhythmogenic mechanisms in the largest cohort of SQTS patients described so far. BACKGROUND: Short QT Syndrome (SQTS) is a rare genetic disorder associated with life-threatening arrhythmias and its natural history is incompletely ascertained. METHODS: Seventy-three SQTS patients (84% males, age 26±15 years, QTc 329±22 ms) were studied and 62 were followed-up for 60±41 months (median 56 months). RESULTS: Cardiac arrest (CA) was the most frequent presenting symptom (40% of probands; range <1 month - 41 years). The rate of CA was 4% in the first year of life and 1.3% per year between 20 and 40 years; the probability of a first CA by the age of 40 years was 41%. Despite the male predominance, females had a risk profile superimposable to that of men (p=0.49). The yield of genetic screening was low (14%), despite familial disease being present in 44% of kindreds. A history of a previous CA was the only predictor of recurrences at follow-up (p<0.0000001). Two patterns of onset of ventricular fibrillation were observed and they were reproducible in patients with multiple CA. Arrhythmias occurred mainly at rest. CONCLUSIONS: SQTS is highly lethal: CA is often the first manifestation of the disease with a peak incidence in the first year of life. Survivors of CA have a high recurrence rate of CA, therefore the implant of a defibrillator is strongly recommended in this group of patients.