In subjects with IVCDs without other evidence of cardiac disease (isolated bundle branch block), published reports show conflicting results. Both right (RBBB) and left bundle branch blocks (LBBB) are associated with adverse outcome in subjects with overt cardiovascular disease (CV Wang et al., 2008 Zhang et al., 2012). The clinical significance of various intraventricular conduction delays (IVCD) depends on the type of the conduction disorder and on the studied patient population. The prognostic impact of LBBB and NSIVCD was affected by the definition of the conduction disorder. Other IVCDs had no significant impact on prognosis. In a population study with long-term follow-up, NSIVCD and Minnesota definition of LBBB were independently associated with CV mortality. The presence of R-R’ pattern was not associated with any adverse outcome. While right bundle branch block, left anterior fascicular block and incomplete bundle branch blocks were associated with seemingly higher mortality, this was no longer the case after adjustment for age and sex. Subjects with NSIVCD were associated with twofold to threefold increase in CV mortality depending on the definition. After controlling for known clinical risk factors, the hazard ratio for CV death, compared with individuals without IVCD, was 1.55 for the Minnesota definition of LBBB (95% confidence interval 1.04–2.31, p = .032) and 1.27 (95% confidence interval 0.80–2.02, p = .308) for the Strauss’ definition of LBBB. Resultsĭuring 16.5 years’ follow-up, 1,309 of the 6,299 subjects (20.8%) died and of these 655 (10.4%) were cardiovascular (CV) deaths. For left bundle branch block (LBBB) and non-specific IVCD (NSIVCD), two different definitions were used. We studied long-term prognostic impact and the association with comorbidities of eight IVCDs in a random sample of 6,299 Finnish subjects (2,857 men and 3,442 women, mean age 52.8, SD 14.9 years) aged 30 or over who participated in the health examination including 12-lead ECG. Such conduction delays may be due to myocardial fibrosis, amyloidosis, cardiomyopathy or hypertrophy.Previous population studies have presented conflicting results regarding the prognostic impact of intraventricular conduction delays (IVCD). Some patients develop nonspecific intraventricular conduction defects without any change in their QRS appearance. Such conduction disturbances may also be superimposed on existing bundle branch blocks and alter their appearance. These conduction delays may be observed after large myocardial infarctions, in which the large necrotic area may cause nonspecific conduction disturbances. Definition and causes of nonspecific intraventricular conduction delayĪccording to the American Heart Association/American College of Cardiology and the Heart Rhythm Society (AHA/ACCF/HRS) recommendations (2009), nonspecific intraventricular conduction delay is defined by “a QRS duration greater than 110 ms in adults, greater than 90 ms in children 8 to 16 years of age, and greater than 80 ms in children less than 8 years of age without meeting the criteria for RBBB or LBBB.” Thus, the appearance of nonspecific intraventricular conduction delay may be rather nuanced. Nonspecific intraventricular conduction delay exists if the ECG displays a widened QRS appearance that is neither a left bundle branch block (LBBB) nor a right bundle branch block (RBBB). Nonspecific intraventricular conduction delay
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