Criteria for differentiating new and old lbbb

Left Bundle Branch Block (LBBB) is a type of abnormal heart rhythm that can be either new or old. Here are some criteria that can help differentiate between new and old LBBB:

New LBBB:

  1. Acute onset: The LBBB develops suddenly, often within hours or days, in response to a cardiac event such as a myocardial infarction (heart attack), cardiitis (inflammation of the heart), or cardiac surgery.
  2. No prior ECG evidence: There is no prior ECG evidence of LBBB, and the patient has never had a similar abnormality.
  3. No underlying heart disease: The patient has no known underlying heart disease, such as coronary artery disease, cardiomyopathy, or valvular heart disease.
  4. Normal cardiac enzymes: Cardiac enzymes, such as troponin and creatine kinase, are normal, indicating that there is no evidence of recent myocardial damage.
  5. No other cardiac abnormalities: There are no other cardiac abnormalities, such as atrial fibrillation, ventricular tachycardia, or bundle branch block in other leads.

Old LBBB:

  1. Chronic presence: The LBBB has been present for a long time, often for years or decades, and has been stable or slowly progressive.
  2. Prior ECG evidence: There is prior ECG evidence of LBBB, and the patient has a known history of the abnormality.
  3. Underlying heart disease: The patient has underlying heart disease, such as coronary artery disease, cardiomyopathy, or valvular heart disease, which is likely contributing to the development of LBBB.
  4. Abnormal cardiac enzymes: Cardiac enzymes are abnormal, indicating that there is evidence of recent or chronic myocardial damage.
  5. Other cardiac abnormalities: There may be other cardiac abnormalities, such as atrial fibrillation, ventricular tachycardia, or bundle branch block in other leads.

Additional criteria:

  1. QRS duration: A new LBBB typically has a QRS duration of 120-130 ms, while an old LBBB may have a longer QRS duration (>130 ms).
  2. QRS morphology: The morphology of the QRS complex may be different in new and old LBBB. New LBBB often has a more prominent R wave in lead V5-V6, while old LBBB may have a more prominent R wave in lead V1-V2.
  3. ECG changes over time: Monitoring the ECG over time can help differentiate between new and old LBBB. New LBBB may show changes in the QRS complex or ST segments over time, while old LBBB is typically stable.

It's important to note that differentiating between new and old LBBB can be challenging, and a thorough clinical evaluation, including a detailed medical history and physical examination, is necessary to make an accurate diagnosis.