Asthma and the risk of cardiac events among patients with long QT Syndrome after age 40

Abstract

Abstract Background The effect of asthma on the clinical course of long QT syndrome (LQTS) in the middle and old age population has not been studied. Purpose The present study was designed to investigate the association between asthma comorbidity, β2-agonist treatment and cardiac events among LQTS subjects after age 40 years. Methods The risk of cardiac events (comprising syncope, aborted cardiac arrest, implantable defibrillator shock, or sudden cardiac death) from age 40 through 75 years, by the presence of asthma and time-dependent β2-agonist use was assessed among 1020 LQTS patients from the LQTS Registry. Results Asthma was identified in 162 (16%) study patients and 63% of asthma patients received β2-agonist inhalers. Patients with asthma vs. no asthma had a higher cumulative rate of cardiac events during follow-up (44% vs. 26%, respectively; p<0.001 [Figure: left panel]). Consistently, multivariate analysis demonstrated that asthma was a powerful predictor of cardiac events with an associated 2-fold (HR=1.97, p=0.001) increased risk for cardiac events as compared to patients with no asthma. β2-agonist inhalers use was associated with a similar increased risk for cardiac events (HR =1.90, p=0.035) among all study patients (Figure: right panel]). Subgroup analysis did not show a statistically significant difference in the association of asthma with cardiac events by risk subsets of LQTS patients, including QTc duration, syncope prior to age 40 years, beta-blocker use, sex, and the LQTS genotype (all p-values for risk subset-by-asthma interaction >0.10). Conclusion The presence of asthma and β2-agonist treatment are associated with an increased risk of cardiac events among middle and old age patients with LQTS.