Left bundle branch block with acute thrombotic occlusion is associated with increased myocardial jeopardy score and poor clinical outcomes in primary percutaneous coronary intervention activations

The use of Smith-modified Sgarbossa criteria to diagnose an extensive anterior acute myocardial infarction in a patient presenting with a left bundle branch block

Patients with LBBB of unknown onset presenting with chest pain can pose a diagnostic challenge in the ED while Smith-Modified-Sgarbossa (SMS) ECG criteria might facilitate AMI diagnosis. We demonstrate a case of a 79-year-old man that presented to the ED with chest pain. Original Sgarbossa criteria were negative for AMI while SMS criteria were applied showing proportionally excessive discordance between ST-segment and preceding S-wave thus fulfilling diagnostic criterion for AMI. The coronary angiogram showed the total occlusion of the culprit left anterior descending artery. In this case, awareness of SMS criteria aided in the early prehospital diagnosis of AMI in the setting of LBBB and impacted the course of treatment.

ST elevation myocardial infarction

ST segment elevation myocardial infarction remains a significant contributor to morbidity and mortality worldwide, despite a declining incidence and better survival rates. It usually results from thrombotic occlusion of a coronary artery at the site of a ruptured or eroded plaque. Diagnosis is based on characteristic symptoms and electrocardiogram changes, and confirmed subsequently by raised cardiac enzymes. Prognosis is dependent on the size of the infarct, presence of collaterals and speed with which the occluded artery is reopened. Mechanical reperfusion by primary percutaneous coronary intervention is superior to fibrinolytic therapy if delivered by an experienced team in a timely fashion. Post-reperfusion care includes monitoring for complications, evaluation of left ventricular function, secondary preventive therapy and cardiac rehabilitation.

Comparison of clinical characteristics and outcomes in patients with left bundle branch block versus ST-elevation myocardial infarction referred for primary percutaneous coronary intervention

AIMS

Recent studies have suggested that a low proportion of patients presenting with left bundle branch block (LBBB) require emergency intervention. In this study, we have compared baseline clinical characteristics, angiographic findings and subsequent outcomes in patients with LBBB versus ST-elevation myocardial infarction (STEMI) referred to our tertiary centre for primary percutaneous coronary intervention (PCI).

METHODS AND RESULTS

A large retrospective observational study was performed involving 1875 consecutive patients presenting to our single tertiary cardiac centre for primary PCI over a 27-month period. Patients presenting with LBBB (n=155, 8.3%) were significantly older (P<0.0001) and were more likely to be female (P<0.0001) and have a prior history of myocardial infarction (P<0.0001) or coronary artery bypass graft surgery (P=0.005). Rates of acute occlusion (12.2 vs. 63%; P<0.0001) and PCI (26 vs. 83%; P<0.0001) were significantly lower in LBBB patients compared with STEMI patients. Although the 30-day mortality was similar, overall mortality during the 2 years of follow-up was significantly higher in the LBBB group compared with the STEMI group (27.8 vs. 13.9%; P=0.023).

CONCLUSION

The incidence of an acutely occluded vessel is low in LBBB when compared with STEMI, but the long-term outcome is significantly worse. Patients with LBBB referred for primary PCI need better risk stratification, and further work is needed to identify potential diagnostic and management strategies.