ABSTRACT
BACKGROUND: Long QT syndrome (LQTS) is a potentially lethal cardiac channelopathy with a 1% to 5% annual risk of LQTS-triggered syncope, aborted cardiac arrest, or sudden cardiac death. OBJECTIVES: This study sought to evaluate LQTS outcomes from a single center in the contemporary era. METHODS: The authors conducted a retrospective study comprising the 606 patients with LQTS (LQT1 in 47%, LQT2 in 34%, and LQT3 in 9%) 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. RESULTS: There were 166 (27%) patients who were symptomatic prior to their first Mayo Clinic evaluation. Median age at first symptom was 12 years. Treatment strategies included no active therapy in 47 (8%) patients, beta-blockers alone in 350 (58%) patients, implantable cardioverter-defibrillators alone in 25 (4%) patients, left cardiac sympathetic denervation alone in 18 (3%) patients, and combination therapy in 166 (27%) patients. Over a median follow-up of 6.7 (IQR: 3.9 to 9.8) years, 556 (92%) patients have not experienced an LQTS-triggered BCE. Only 8 of 440 (2%) previously asymptomatic patients have experienced a single BCE. In contrast, 42 of 166 (25%) previously symptomatic patients have experienced ≥1 BCE. Among the 30 patients with ≥2 BCEs, 2 patients have died and 3 LQT3 patients underwent cardiac transplantation. CONCLUSIONS: Although outcomes have improved markedly, further optimization of treatment strategies is still needed given that 1 in 4 previously symptomatic patients experienced at least 1 subsequent, albeit nonlethal, LQTS-triggered cardiac event.
Subject(s)
Death, Sudden, Cardiac/epidemiology , Electric Countershock/methods , Heart Conduction System/physiopathology , Long QT Syndrome/epidemiology , Adolescent , Adult , Child , Child, Preschool , Electrocardiography , Female , Follow-Up Studies , Humans , Incidence , Long QT Syndrome/physiopathology , Long QT Syndrome/therapy , Male , Minnesota/epidemiology , Prognosis , Retrospective Studies , Survival Rate/trends , Time Factors , Young AdultABSTRACT
BACKGROUND: Videoscopic left cardiac sympathetic denervation (LCSD) is an adjunct therapy for reduction of arrhythmia-induced events in patients with long-QT syndrome (LQTS). LCSD reduces LQTS-triggered breakthrough cardiac events. The temporal effects of QTc changes post-LCSD have not been studied. METHODS: We utilized continuous QTc monitoring on 72 patients with LQTS. We evaluated acute and long-term QTc changes in comparison to 12-lead ECG-derived QTc values prior to surgery, 24 hours postsurgery, and at follow up ≥3 months. RESULTS: Seventy-two patients underwent LCSD at our institution (46% male, mean age at LCSD was 14 ± 10 years). The mean baseline, pre-LCSD QTc was 505 ± 56 ms, which had decreased significantly at ≥3 months post-LCSD to 491 ± 40 ms (P = 0.001). QTc monitoring revealed that the majority of the cohort (53/72; 74%) had a transient increase >30 ms in QTc from baseline, with an average maximum increase of 72 ± 30 ms. Resolution within 10 ms of baseline or less occurred in 57% (30/53) at 24 hours post-LCSD. CONCLUSIONS: Although LQTS patients may have a paradoxically increased QTc post-LCSD, the effects are transient in most patients. Importantly, no patients experienced any arrhythmias in the postoperative setting related to this transient rise in QTc.
Subject(s)
Electrocardiography, Ambulatory , Heart Rate , Heart/innervation , Long QT Syndrome/surgery , Sympathectomy/methods , Thoracic Surgery, Video-Assisted/methods , Action Potentials , Adolescent , Child , Child, Preschool , Female , Humans , Long QT Syndrome/diagnosis , Long QT Syndrome/physiopathology , Male , Predictive Value of Tests , Retrospective Studies , Signal Processing, Computer-Assisted , Software , Sympathectomy/adverse effects , Thoracic Surgery, Video-Assisted/adverse effects , Time Factors , Treatment Outcome , Young AdultABSTRACT
BACKGROUND: Long QT syndrome (LQTS) is a potentially lethal but highly treatable cardiac channelopathy. Treatment options include pharmacotherapy, device therapy, and left cardiac sympathetic denervation (LCSD). Here, we sought to determine the characteristics of LQTS patients who have had ≥1 LQTS-related breakthrough cardiac event (BCE) after LCSD. METHODS AND RESULTS: We performed retrospective chart review for 52 consecutive patients (24 males; mean age at diagnosis, 10.0±10 years; mean QTc, 528±74 ms) with LQTS who underwent LCSD between 2005 and 2010 (mean age at LCSD, 14.1±10 years) and have been followed up for 3.6±1.3 years. A BCE was defined as either (1) an appropriate ventricular fibrillation-terminating implantable cardioverter defibrillator shock or (2) arrhythmogenic syncope, seizures, or aborted cardiac arrest after LCSD. Thirty-three patients (61%) had LCSD as primary prevention because of either high-risk assessment or ß-blocker intolerance. So far, 12 of 52 (23%) patients (7 males) have experienced ≥1 BCE post LCSD. The clinical phenotype of patients with BCEs was significantly more severe than patients without a BCE. No BCEs were seen in patients undergoing LCSD for ß-blocker intolerance (0/12 versus 17/40; P<0.001). CONCLUSIONS: Although a marked reduction in number of cardiac events is usually seen after LCSD, ≈50% of high-risk LQTS patients have experienced ≥1 post-LCSD breakthrough. Therefore, LCSD must not be viewed as curative or as an alternative in implantable cardioverter defibrillator for high-risk patients. Prophylactic LCSD may provide another option to counter a suboptimal quality of life resulting from medication-related side effects.
