Atrial fibrillation and atrial vulnerability in patients with Brugada syndrome.

OBJECTIVES: We sought to study atrial vulnerability in patients with Brugada syndrome. BACKGROUND: Atrial fibrillation (AF) often occurs in patients with Brugada syndrome, but atrial vulnerability in Brugada syndrome has not been evaluated. METHODS: The patient group consisted of 18 patients with Brugada syndrome. The control group consisted of 12 age- and gender-matched subjects who had neither organic heart disease nor AF episodes. The incidence and clinical characteristics of AF were evaluated in all 18 patients with Brugada syndrome, and an electrophysiologic study was performed in all 12 control subjects and in 14 of the 18 patients with Brugada syndrome. The atrial effective refractory period of the right atrium (RA-ERP), intra-atrial conduction time (conduction time from the stimulus at the right atrium to atrial deflection at the distal portion of the coronary sinus), duration of local atrial potential, and repetitive atrial firing (occurrence of two or more premature atrial complexes after atrial stimulation) were studied. RESULTS: Spontaneous AF occurred in 7 of the 18 patients with Brugada syndrome but in none of the control subjects. The RA-ERP was not different between the two groups. The intra-atrial conduction time was increased in the Brugada syndrome group versus the control group (168.4 +/- 17.5 vs. 131.8 +/- 13.0 ms, p < 0.001). The duration of atrial potential at the RA-ERP was prolonged in the Brugada syndrome group versus the control group (80.3 +/- 18.0 vs. 59.3 +/- 9.2 ms, p < 0.001). Repetitive atrial firing was induced in nine patients with Brugada syndrome and in six control subjects. Atrial fibrillation was induced in eight patients with Brugada syndrome but in none of the control subjects. In patients with Brugada syndrome without spontaneous AF, the intra-atrial conduction time and duration of atrial potential were also increased. CONCLUSIONS: Atrial vulnerability is increased in patients with Brugada syndrome. Abnormal atrial conduction may be an electrophysiologic basis for induction of AF in patients with Brugada syndrome.

Prevalence of subclinical coronary artery disease in ischemic stroke patients.

BACKGROUND: Recently, ischemic stroke has emerged as a new coronary artery disease (CAD) risk equivalent. Our purpose is to study the prevalence of CAD in ischemic stroke patients compared with that in non-stroke patients. METHODS AND RESULTS: We measured coronary calcium score (CCS) in 151 ischemic stroke patients without known CAD (stroke group) and compared it with 151 age- and sex-matched non-stroke patients (control group). CCS was significantly higher in the stroke group than in the control group (stroke group, median: 64, interquartile range: 3-382 vs. control group, median: 3, interquartile range: 0-65, p<0.0001). High-risk CAD, defined as a CCS≥400, was detected in 24.5% of the stroke group compared with 9.3% of the control group (p<0.0001). Agreement between the Framingham risk score and CCS was found in only 62 patients (41.1%). In a multiple logistic regression analysis, age [hazard ratio (HR) 1.09, 95% confidence interval (CI) 1.03-1.14], diabetes (HR 2.97, 95%CI 1.52-5.78), stroke (HR 3.85, 95%CI 1.89-7.81), and male sex (HR 4.41, 95%CI 1.82-0.75) were significantly associated with high-risk CAD (p<0.001). CONCLUSIONS: Our results show that the prevalence of subclinical CAD in ischemic stroke patients was high, and that a quarter of them had high-risk CAD. Age, diabetes, stroke, and male sex were independent predictors of high-risk CAD.

Fragmented QRS is associated with torsades de pointes in patients with acquired long QT syndrome.

BACKGROUND: Acquired long QT syndrome (LQTS) is a disease due to a secondary repolarization abnormality induced by various predisposing factors. In contrast to congenital LQTS, risk factors that produce acquired LQTS include organic heart diseases that often exhibit depolarization abnormality. Although various repolarization parameters have been evaluated in acquired LQTS, the existence of depolarization abnormality in association with torsades de pointes (TdP) has not been reported. OBJECTIVE: The purpose of this study was to evaluate both repolarization (QT components) and depolarization parameters (fragmented QRS [fQRS]) in acquired LQTS patients with markedly prolonged QT interval. METHODS: Seventy patients with acquired severe QT prolongation (QTc ≥ 550 ms) were studied. Thirty-two patients had syncope or TdP (syncope group). Thirty-eight patients did not have any symptoms (asymptomatic group). The existence of fQRS and QT components (QT, QTc, Tpe [interval between peak and end of T wave] intervals, and U-wave voltage) was analyzed. RESULTS: The syncope group had more frequent fQRS (81%) than did the asymptomatic group (21%, P < .01) and the incidence of fQRS was not different before and after removal of predisposing factors. The incidence of organic heart disease was not different between the two groups. No differences in QTc interval were noted between the syncope and asymptomatic groups, although the syncope group had longer QT and Tpe intervals and higher U wave than the asymptomatic group (P < .01). CONCLUSION: Acquired predisposing factors promoted repolarization abnormality (especially prolongation of QT and Tpe intervals), and the existence of fQRS had an important role in the development of TdP in patients with acquired LQTS.