A 68-year-old woman with a recent anterior wall myocardial infarction develops sudden right-sided weakness and speech difficulty. Neuroimaging confirms acute left middle cerebral artery stroke. Which investigation is most specific for confirming the suspected cardioembolic source?

Explanation

## Confirming Cardioembolic Stroke Source ### Clinical Scenario Analysis This patient has **post-MI stroke**, a classic presentation of **cardioembolic stroke** due to: - Left ventricular mural thrombus formation (post-anterior MI) - Reduced ejection fraction and wall motion abnormality - Stasis of blood in the akinetic segment ### Why TEE is the Gold Standard **Key Point:** TEE is the **most sensitive and specific investigation** for detecting intracardiac thrombi and confirming the cardioembolic mechanism of stroke. **High-Yield:** TEE sensitivity for LV thrombus detection: - **TEE: 90–95%** (gold standard) - TTE: 40–60% (limited by acoustic window) - CT: 70–80% (lower sensitivity than TEE) ### Diagnostic Approach to Acute Ischemic Stroke ```mermaid flowchart TD A[Acute ischemic stroke]:::outcome --> B{Stroke mechanism?}:::decision B -->|Cardioembolic suspected| C[Recent MI? AF? Valve disease?]:::decision B -->|Atherosclerotic| D[Carotid/vertebral imaging]:::action B -->|Lacunar/Other| E[MRI DWI]:::action C -->|Yes| F[TEE for cardiac source]:::action F --> G[Confirm intracardiac thrombus]:::outcome G --> H[Anticoagulation therapy]:::action ``` ### Why TEE Over Other Modalities | Investigation | Sensitivity for LV Thrombus | Specificity | Best For | Limitation | |---|---|---|---|---| | **TEE** | 90–95% | >95% | **Definitive source identification** | Operator-dependent, semi-invasive | | TTE | 40–60% | High | Screening, ejection fraction | Poor visualization of LA/LAA | | CT | 70–80% | High | Exclude hemorrhage, assess extent | Lower sensitivity than TEE | | Carotid duplex | N/A | N/A | Atherosclerotic disease | Does NOT assess cardiac source | ### Clinical Implications **Clinical Pearl:** TEE findings directly guide **anticoagulation strategy**: - **Thrombus confirmed:** Immediate anticoagulation (heparin → warfarin/DOAC) - **No thrombus but high-risk features:** Consider anticoagulation despite negative TEE - **Timing:** TEE should be performed **within 24–48 hours** of stroke onset for optimal yield **Mnemonic: CARDIOEMBOLI sources** — **C**ardiomyopathy, **A**trial fibrillation, **R**heumatic valve, **D**ilated chambers, **I**nfective endocarditis, **O**pened foramen ovale, **E**jection fraction <35%, **M**yocardial infarction, **B**ioprothetic valve, **O**ther (prosthetic valves), **L**eft atrial appendage, **I**ntracardiac thrombus. [cite:Harrison 21e Ch 296; Robbins 10e Ch 4]