ABSTRACT
Introduction: The presence of a Q-wave on a 12-lead electrocardiogram (ECG) has been considered a marker of a large myocardial infarction (MI). However, the correlation between the presence of Q-waves and nonviable myocardium is still controversial. The aims of this study were to 1) test QWA, a novel ECG approach, to predict transmural extent and scar volume using a 3.0 Tesla scanner, and 2) assess the accuracy of QWA and transmural extent. Methods: Consecutive patients with a history of coronary artery disease who came for myocardial viability assessment by CMR were retrospectively enrolled. Q-wave measurements parameters including duration and maximal amplitude were performed from each surface lead. A 3.0 Tesla CMR was performed to assess LGE and viability. Results: Total of 248 patients were enrolled in the study (with presence (n ¼ 76) and absence of pathologic Q-wave (n ¼ 172)). Overall prevalence of pathologic Q-waves was 27.2% (for LAD infarction patients), 20.0 % (for LCX infarction patients), and 16.8% (for RCA infarction patients). Q-wave area demonstrated high performance for predicting the presence of a nonviable segment in LAD territory (AUC 0.85, 0.77e0.92) and a lower, but still significant performance in LCX (0.63, 0.51e0.74) and RCA territory (0.66, 0.55e0.77). Q-wave area greater than 6 ms mV demonstrated high performance in predicting the presence of myocardium scar larger than 10% (AUC 0.82, 0.76e0.89). Conclusion: Q-wave area, a novel Q-wave parameter, can predict non-viable myocardial territories and the presence of a significant myocardial scar extension.
ABSTRACT
<p><b>INTRODUCTION</b>Brugada syndrome (BrS) is a common genetic cause of sudden cardiac arrest (SCA) due to polymorphic ventricular tachycardia and ventricular fibrillation. The current recommended therapy for high-risk BrS patients is the use of an implantable cardioverter defibrillator (ICD). The present study aimed to report the clinical characteristics and treatment outcomes of BrS patients in northeastern Thailand.</p><p><b>METHODS</b>Patients who were diagnosed with BrS or had a Brugada electrocardiogram (ECG) between 2005 and 2012 at Khon Kaen University's hospitals were enrolled in the present study. Patients' clinical characteristics, ECG type, laboratory results and treatment were reviewed.</p><p><b>RESULTS</b>A total of 90 eligible patients were enrolled. Of these, 79 (87.8%) patients were symptomatic--65 (82.3%) had documented SCA and 14 (17.7%) had unexplained syncope. The remaining 11 (12.2%) patients were asymptomatic with Brugada ECG. A majority of the patients enrolled were born in northeastern Thailand. The mean age of the symptomatic patients was 44.49 ± 8.55 years. Among the symptomatic patients, a majority were male (n = 77, 97.5%) and 23 (29.1%) patients had a family history of SCA. Almost all BrS patients who were symptomatic (96.2%) received ICD treatment for secondary prevention. The number of patients who received appropriate ICD therapy was 4.2 times of those who received inappropriate shocks. Only 3 (3.8%) symptomatic BrS patients refused ICD treatment.</p><p><b>CONCLUSION</b>Clinical characteristics did not distinguish between symptomatic BrS patients and asymptomatic patients with Brugada ECGs. The clinical characteristics and treatment outcomes for the symptomatic BrS patients with SCA and unexplained syncope were similar. Among the BrS patients implanted with secondary prevention ICD in Northeastern Thailand, nearly one-third had received appropriate ICD therapy, far exceeding the incidence of device-related complications and inappropriate therapy.</p>