Key result
New or presumed new LBBB was not associated with a higher rate of confirmed myocardial infarction compared to previously known LBBB (33% vs 37%, p=0.912).
Why the study?
Does the chronicity of left bundle branch block (new vs. old) affect the likelihood of myocardial infarction and the use of reperfusion treatment in patients with suspected MI?
Observational (n=99)
No
Does the chronicity of left bundle branch block (new vs. old) affect the likelihood of myocardial infarction and the use of reperfusion treatment in patients with suspected MI?
In patients with suspected MI and LBBB, new LBBB triggers more reperfusion therapy than old LBBB, despite both groups having similar actual rates of MI, suggesting LBBB chronicity may be a poor predictor of acute MI.
Answers are grounded in this paper and cite their sources.
Questions differential reperfusion based on LBBB chronicity in suspected MI; leaves open need for improved diagnostic criteria.
Our aim was to investigate if patients with suspected myocardial infarction (MI) and a new or presumed new left bundle branch block (nLBBB) were treated according to the ESC reperfusion guidelines and to compare them with patients having a previously known LBBB (oLBBB). Furthermore, we investigated the prevalence of ST-segment concordance in this population. Retrospective data was collected from the Swedeheart registry for patients admitted to the cardiac care unit at Örebro University Hospital with LBBB and suspected MI during 2009 and 2010. The patients were divided in two age groups; <80 or ≥80 years and analysed for LBBB chronicity (nLBBB or oLBBB), MI, and reperfusion treatment. We also compared our data with the national Swedeheart database for 2009. A total of 99 patients fulfilled the inclusion criteria. A diagnosis of MI was significantly more common in the group ≥80 years compared to the group <80 years (53.8 vs. 25%, p=0.007). The rate of MI was similar in the groups with nLBBB and oLBBB (33 and 37% respectively, p=0.912). Of the 36 patients with a final diagnosis of MI, only eight (22%) had nLBBB. Reperfusion treatment, defined as an acute coronary angiography with or without intervention, was significantly more often performed in patients with nLBBB compared to patients with oLBBB (42 vs. 8%, p<0.001). The rate of MI and reperfusion treatment did not differ between our institution and the Swedish national data. ST-concordance was present in only two cases, one of which did not suffer an MI. The proportion of patients receiving reperfusion treatment was low, but higher in nLBBB, reflecting a partial adherence to the guidelines. We found no correlation between LBBB chronicity and MI. Furthermore, only a minority of the MIs occurred in patients with nLBBB. ST-concordance was found in only one of 36 MI cases, indicating lack of sensitivity for this test.
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Liakopoulos et al. (2013) conducted an observational in Suspected myocardial infarction with left bundle branch block (n=99). New or presumed new LBBB (nLBBB) vs. Previously known LBBB (oLBBB) was evaluated on Rate of myocardial infarction (p=0.912). New or presumed new LBBB was not associated with a higher rate of confirmed myocardial infarction compared to previously known LBBB (33% vs 37%, p=0.912).
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