From the Guidelines
For a patient with new left bundle branch block (LBBB) presenting with chest pain and shortness of breath, the next step should be immediate evaluation for acute coronary syndrome, particularly myocardial infarction, as indicated by the most recent guidelines 1. The patient should be sent to the emergency department for an urgent ECG, cardiac biomarkers (troponin), and cardiology consultation.
- New LBBB in the setting of chest pain is considered a high-risk presentation and may warrant emergent coronary angiography with possible percutaneous coronary intervention, as suggested by the 2020 ESC guidelines for the management of acute coronary syndromes in patients presenting without persistent ST-segment elevation 1.
- While awaiting definitive care, the patient should receive aspirin 325 mg, supplemental oxygen if oxygen saturation is low, and consideration of nitroglycerin 0.4 mg sublingually for ongoing chest pain if blood pressure allows.
- Additional initial management may include IV access, pain control, and cardiac monitoring. The urgency stems from the fact that new LBBB can mask ST-segment elevation on ECG, potentially hiding an acute myocardial infarction, and when combined with typical symptoms like chest pain and dyspnea, represents a high-risk presentation requiring prompt intervention to minimize myocardial damage and prevent complications, as highlighted in the 2013 ACCF/AHA guideline for the management of ST-elevation myocardial infarction 1. It is also important to note that more than 50% of patients presenting with acute chest pain and LBBB to the emergency department or chest pain unit will ultimately be found to have a diagnosis other than MI, as stated in the 2020 ESC guidelines 1. However, the initial approach should prioritize the possibility of an acute coronary syndrome due to the potential for significant morbidity and mortality associated with delayed diagnosis and treatment. The 2018 ACC/AHA/HRS guideline on the evaluation and management of patients with bradycardia and cardiac conduction delay also emphasizes the importance of considering underlying structural heart disease in patients with LBBB, but this does not alter the initial approach to a patient presenting with symptoms suggestive of acute coronary syndrome 1.
From the Research
Next Steps for Patient with New Left Bundle Branch Block
- The patient presents with symptoms of chest pain and shortness of breath, which can be indicative of acute myocardial infarction (AMI) or other cardiac conditions 2, 3, 4, 5.
- An electrocardiogram (ECG) showing a new left bundle branch block (LBBB) can make diagnosis of AMI challenging, but certain signs such as Chapman's sign may indicate myocardial ischemia 2.
- The presence of ST-segment changes on the ECG can be specific for the diagnosis of AMI in patients with LBBB, and these patients may have a higher mortality rate 4.
- Patients with LBBB are often at high risk of morbidity and mortality, and may be treated less aggressively than those with ST-elevation myocardial infarction (STEMI) 5.
- Consideration should be given to further diagnostic testing, such as serial troponin levels, coronary catheterization, or other imaging studies to determine the underlying cause of the patient's symptoms 2, 3, 4.
- Management of the patient may involve treatment with heparin, aspirin, beta-blockers, and other medications, as well as consideration of cardiac resynchronization therapy or other interventions 6, 5.