Treatment strategies for patients with LQTS need improvement
There remains a strong need to further enhance treatment strategies despite improved outcomes in patients with long QT syndrome (LQTS), given that one in four previously symptomatic patients have at least one subsequent, albeit nonlethal, LQTS-triggered cardiac event, a recent study suggests.
To assess LQTS outcomes in the contemporary era, researchers conducted a retrospective study including 606 patients with LQTS (LQT1 in 47 percent, LQT2 in 34 percent and LQT3 in 9 percent) who were evaluated in Mayo Clinic’s Genetic Heart Rhythm Clinic from January 1999 to December 2015.
Breakthrough cardiac events (BCEs) were defined as LQTS-attributable syncope or seizures, aborted cardiac arrest, appropriate ventricular fibrillation‒terminating implantable cardioverter-defibrillator shocks, and sudden cardiac death.
A total of 166 patients (27 percent; median age at first symptom, 12 years) were symptomatic before their first Mayo Clinic evaluation.
The following treatment strategies applied in patients were no active therapy (n=47; 8 percent), beta-blockers alone (n=350; 58 percent), implantable cardioverter-defibrillators alone (n=25; 4 percent), left cardiac sympathetic denervation alone (n=18; 3 percent) and combination therapy (n=166; 27 percent).
There were 556 patients (92 percent) who did not experience an LQTS-triggered BCE over a median follow-up of 6.7 years (interquartile range, 3.9 to 9.8 years). Only eight of 440 (2 percent) previously asymptomatic patients experienced a single BCE. Of the 166 previously symptomatic patients, however, 42 (25 percent) experienced ≥1 BCE.
Furthermore, two of the 30 patients with ≥2 BCEs died and three LQT3 patients underwent cardiac transplantation.
“LQTS is a potentially lethal cardiac channelopathy with a 1- to 5-percent annual risk of LQTS-triggered syncope, aborted cardiac arrest or sudden cardiac death,” according to researchers.