See also: [Sgarbossa](bear://x-callback-url/open-note?id=D6C65DD8-FFFA-41E0-AE1C-CB0F6071EB9B-824-00000027C1A1BC46&header=Sgarbossa,%20Left%20bundle%20branch%20block), [[Ventricular Tachycardia]], [[Right Bundle Branch Block]], [[STEMI equivalents|sgarbossa]] # Definition >[!Definition] >1. QRS duration > 120ms >2. **Dominant S wave** in ==v1== >3. Broad **monophasic R wave in lateral leads** (==v5-v6==, I, aVL) >4. Absence of Q waves in lateral leads >5. Prlonged R wave peak time >60ms V5-V6 Associated features include: - left axis deviation - poor r progression in precordial leads - appropriate discordance ## QRS Morphology in v1 rS complex or QS comple ![[Pasted image 20230405184205.png]]**** ## Monophasic R wave in lateral leads ![[Pasted image 20230405184429.png]] ## QRS morphology in latearl leads R wave in lateral leads may be either "M" shaped, notched, monophasic, or an RS complex ![[Pasted image 20230405184520.png]] # Causes - Aortic stenosis - Ischaemic heart disease - HTN - dilated cardiomyopathy - anterior MI - [[hyperkalemia]] - [[Digoxin toxicity]] ![[Pasted image 20230516154235.png]] # LBB and ACS algorithm ```mermaid graph TB A["Suspected ACS and LBBB (new or old)"] --> B["Haemodynamic instability or acute heart failure"] B -- no --> C["Sgarbossa concordance on ECG?"] B -- yes --> D[Emergent reperfussion by PCI or fibrinolysis] C -- no --> E["Bedside echocardiography and/or serial trops"] C -- yes --> F[STEMI-equivalent] F --> D E -- RWMA --> D E --> G[NSTEMI, UA, or non-ACS] style F fill:#f9f,stroke:#333 ``` source: [Evolving considerations in the management of patients with left bundle branch block and suspected myocardial infarction.](bookends://sonnysoftware.com/ref/DL/232063)