Identification of Low-Risk Adult Congenital LQTS Patients

To date, most risk stratification studies in long-QT syndrome (LQTS) have focused on identification of high-risk subjects. Current data on the long-term clinical course of low-risk adult LQTS patients are limited.

Patients in this study were from the Rochester-based LQTS Registry. We hypothesized that long-term survival of LQT1-2 patients with QTc <500 milliseconds and no cardiac symptoms before age 20 (n = 523) would be similar to that of their unaffected genotype-negative family members (n = 1,134). Kaplan-Meier survival analysis and multivariate Cox proportional hazards regression models were used to evaluate the incidence and risk of all-cause mortality in the study population. The low-risk LQTS study group comprised 27% (523/1,919) of genetically confirmed LQTS Registry patients alive at age 20. The cumulative probability of all-cause mortality between age 20 and 65 was similar in the low-risk LQTS group and the genotype-negative control group (4.3% and 4.4%, respectively at age 65; P = 0.49 for overall difference). Multivariate analysis showed no significant difference in the risk of all-cause mortality between the 2 groups (HR = 0.89; 95% CI 0.33-2.43, P = 0.82). Consistent results were revealed in subgroup analyses in female and male LQTS patients and in patients with genetically identified LQT1 and LQT2 mutations.

We identified a sizeable proportion of low-risk, adult LQTS patients with no cardiac symptoms before age 20 and QTc<500 milliseconds who had 45-year survival similar to unaffected family members.