Background-Data on the clinical presentation and genotype-phenotype correlation of patients with congenital long-QT syndrome (LQTS) diagnosed at perinatal through infantile period are limited. A nationwide survey was conducted to characterize how LQTS detected during those periods is different from that in childhood or adolescence. Methods and Results-Using questionnaires, 58 cases were registered from 33 institutions. Diagnosis (or suspicion) of LQTS was made during fetal life (nϭ18), the neonatal period (nϭ31, 18 of them at 0 to 2 days of life), and beyond the neonatal period (nϭ9). Clinical presentation of LQTS included sinus bradycardia (nϭ37), ventricular tachycardia/torsades de pointes (nϭ27), atrioventricular block (nϭ23), family history of LQTS (nϭ21), sudden cardiac death/aborted cardiac arrest (nϭ14), convulsion (nϭ5), syncope (nϭ5), and others. Genetic testing was available in 41 (71%) cases, and the genotype was confirmed in 29 (71%) cases, consisting of LQT1 (nϭ11), LQT2 (nϭ11), LQT3 (nϭ6), and LQT8 (nϭ1). Ventricular tachycardia/torsades de pointes and atrioventricular block were almost exclusively observed in patients with LQT2, LQT3, and LQT8, as well as in those with no known mutation. In LQT1 patients, clues to diagnosis were mostly sinus bradycardia or family history of LQTS. Sudden cardiac death/aborted cardiac arrest (nϭ14) was noted in 4 cases with no known mutations as well as in 4 genotyped cases, although the remaining 6 did not undergo genotyping. Their subsequent clinical course after aborted cardiac arrest was favorable with administration of ␤-blockers and mexiletine and with pacemaker implantation/implantable cardioverter-defibrillator. Conclusions-Patients with LQTS who showed life-threatening arrhythmias at perinatal periods were mostly those with LQT2, LQT3, or no known mutations. Independent of the genotype, aggressive intervention resulted in effective suppression of arrhythmias, with only 7 deaths recorded. (Circ Arrhythm Electrophysiol. 2010;3:10-17.)

Reports on the incidence of persistent left superior vena cava (PLSVC) in the normal population are limited to studies involving pacemaker implantation candidates and cadavers. The incidence in patients with congenital heart diseases (CHDs) is estimated to be higher than that in the normal population; however, the details are unclear. To investigate the incidence of PLSVC in the normal population and in patients with CHDs, subjects were examined prospectively using echocardiography. Normal subjects consisted of 2841 successive neonates without intra-cardiac or congenital anomalies born in Gifu Prefectural General Medical Center. Additionally, 1920 patients with CHDs were evaluated. The incidence of PLSVC in normal neonates was 0.21% (95% confidence interval 0.042-0.38%). A high incidence (more than 7.0 times the incidence in normal subjects) was observed in all CHD patients. The high incidence group included coarctation of the aorta (CoA) (23.7%) and double outlet right ventricle (DORV) patients (24.6%). The second group consisted of CHD patients with ventricular septal defect (VSD), with an incidence ranging from 5.1 to 6.1%. The low incidence group comprised patients with other CHDs, with an incidence between 1.5 and 3.1%. The incidence of PLSVC in trisomy 21 and atrial septal defect patients was significantly higher than that in normal neonates. The incidence of PLSVC in the normal population and in patients with CHDs was systematically evaluated for the first time. The incidence in CHD patients appeared to be positively influenced by the type of CHD, particularly by DORV, CoA, and VSD.

Background— Prevalence of microvolt T-wave alternans (TWA) and the strength of its association with torsade de pointes (TdP) history have not been fully investigated in patients with long QT syndrome (LQTS). Methods and Results— Twenty-four–hour continuous 12-lead ECGs were recorded in 10 healthy subjects (5 men; median age, 21.5 years) and 32 patients (13 men; median age, 13 years) with LQTS types 1 (n=18), 2 (n=4), 3 (n=4), and unidentified (n=6). Peak TWA was determined by the Modified Moving Average method. None of the healthy subjects had TWA ≥42 µV. All 8 (100%) LQTS patients with a history of TdP exhibited TWA ≥42 µV, whereas only 14 (58.3%) of the 24 LQTS patients without TdP history reached ≥42 µV (p=0.04). Thus, the 42-µV cut point provided 100% sensitivity and 41.7% specificity for an association with TdP history. In the 22 (68.8%) LQTS patients with TWA ≥42 µV, only 2 (median; interquartile range, 1–3) leads exhibited TWA ≥42 µV. Highest TWA levels were recorded in precordial leads (V 1 –V 6 ) in 30 (93.8%) patients, most frequently in lead V 2 (43.8%). A single ECG lead detected only ≤63.6% of TWA ≥42 µV episodes, whereas the combined leads V 2 to V 5 detected 100% of TWA ≥42 µV. Conclusions— Microvolt TWA is far more prevalent in LQTS patients than previously reported and is strongly associated with TdP history. TWA should be monitored from precordial leads in LQTS patients. The use of a limited set of ECG leads in conventional monitoring has led to underestimation of TWA and its association with TdP.