Ende, M.Y. van der (Maaike Yldau) (2015) The importance of bundle branch block in the general population and in patients with ST-elevation myocardial infarction. thesis, Medicine.
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Abstract
Background: There is a consensus that presence of bundle branch block (BBB) in the general population is associated with cardiovascular events. However, the majority of studies focusing on the prevalence of BBB in the general population date back to the 1990s. Since then, there have been significant changes in lifestyle. Recent studies only report either the incidence of a right BBB (RBBB) only or general conduction disorders observed in a population older than 30 years of age. With respect to patients with acute ST-elevation myocardial infarction (STEMI) and BBB, higher in-hospital and long-term unadjusted mortality and lower left ventricular ejection fraction (LVEF) have been reported, irrespective of whether the observed BBB was left or right. It is important to consider that most of these findings are based on the outdated recommendation of thrombolysis for treating patients with STEMI. Nevertheless, since the 1990s, primary angioplasty has become the gold standard, which has led to a significant improvement in outcome when treating STEMI. In light of the aforementioned, the aims underlying this study are to determine the prevalence of conduction disorders and subsequently investigate potential associations between conduction disorders and cardiovascular events in the contemporary population. Following this, an additional aim is to investigate the effect of BBB on mortality and LVEF in STEMI patients treated with the current recommendation of angioplasty. Methods: The importance of BBB in the general population was investigated in the LifeLines database, a three generation cohort study and biobank. All 152.180 participants of LifeLines were included for determining the prevalence of BBB. For further analyses participants were excluded when no follow-up data was available, or when participants had a medical history of possible myocardial infarction (MI). Logistic regression was used to study the relationship between BBB and MI during follow-up. For determining the outcome of STEMI patients with BBB, a total of 1123 patients with STEMI treated in the University Medical Center Groningen from January 2011 until May 2013 were included. The follow-up period was 2 to 4 years. Transthoracic echocardiography was performed to evaluate LVEF within 6 months after STEMI. Baseline characteristics were compared between patients with and without a BBB. Relative risk of death and reduced LVEF between groups were determined using Cox survival analyses and ordered logistic regression. Results: In the general population, the prevalence of BBB increased significantly with age and was more common in males. Furthermore, LBBB was associated with MI and mortality during follow-up. In STEMI patients, a significant difference in two-year mortality was observed between patients with and without BBB; 25% (n=18) and 9.3% (n=94, p<0.001) respectively. Mortality observed in patients with LAFB was 15% (n=8). Patients with BBB more frequently presented a severely reduced LVEF compared to patients without BBB; 19% (n=8) and 3.6% (n=23, p<0.001) respectively. In addition, patients with BBB less frequently presented a normal LVEF compared to patients without BBB; 14% (n=6) and 43% (n=287, p<0.001) respectively. For patients with LAFB, 18% (n=5) had a severely reduced LVEF. In multivariate analysis, including adjustment for LVEF, BBB or LAFB were not independently associated with mortality, but presence of BBB was an independent predictor of reduced LVEF. Conclusion: In the general population, the prevalence of BBB increased with age and is higher in males. LBBB was associated with MI and mortality during follow-up. In STEMI patients, BBB was an independent predictor of reduced LVEF. Conversely, BBB was not an independent predictor of mortality in the current era of reperfusion therapy.
| Item Type: | Thesis (Thesis) |
|---|---|
| Supervisor name: | Harst, Prof. dr. P. van der and Hartman, Drs. H.T. |
| Faculty: | Medical Sciences |
| Date Deposited: | 25 Jun 2020 10:54 |
| Last Modified: | 25 Jun 2020 10:54 |
| URI: | https://umcg.studenttheses.ub.rug.nl/id/eprint/1509 |
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