STEMI criteria show similar accuracy in right BBB, non-BBB patients

The ECG criteria used for identifying patients with ST-elevation myocardial infarction (STEMI) demonstrates similar diagnostic accuracy in right bundle branch block (BBB) and non-BBB patients, according to a study. 

However, STEMI is usually seen in patients presenting with right BBB who do not fulfill the diagnostic ECG criteria. 

Overall, 2,139 patients with suspected STEMI underwent triage to acute coronary angiography based on a prehospital 12-lead ECG. The authors then compared the sensitivity and specificity for STEMI-ECG criteria in right BBB and non-BBB patients. They also calculated the adjusted hazard ratio (HR) for 1-year overall mortality. 

STEMI was examined in 1,832 of 2,139 patients (85.6 percent) and in 102 of 117 right BBB patients (87.2 percent). In most patients presenting with right BBB, the ST-segment deviation followed typical ST-T patterns. Of the 17 right BBB patients with no significant ST changes, 14 underwent STEMI assessment (82 percent). 

STEMI criteria showed a comparable diagnostic accuracy between right BBB and non-BBB patients for inferior (sensitivity: 51.1 percent vs 59.1 percent; p=0.14; specificity: 66.7 percent vs 52.1 percent; p=0.33) and anterior STEMI (sensitivity: 35.2 percent vs 36.6 percent; p=0.80; specificity: 58.3 percent vs 49.5 percent; p=0.55). 

On the other hand, the diagnostic performance was lower for lateral STEMI in patients with right BBB (sensitivity: 14.8 percent vs 4.4 percent; p=0.001; specificity: 75.0 percent vs 98.4 percent; p<0.001). 

Notably, 1-year mortality was higher for patients with right BBB than those with non-BBB (HR, 2.3 percent, 95 percent confidence interval, 1.25−4.21). 

“Right BBB patients showed poorer outcome after 1 year,” the authors said. “Consequently, the presence of right BBB in suspected STEMI cases signifies a high-risk feature, aligning with established guidelines.”