A 72-year-old man with COPD and a 40 pack-year smoking history presents with sudden onset dyspnea and syncope. On examination: BP 88/56 mmHg, HR 128/min, JVD prominent, right ventricular heave palpable. Chest X-ray shows no acute infiltrate. ECG shows sinus tachycardia and T-wave inversion in leads V1–V4. Troponin I is elevated at 0.18 ng/mL (normal <0.04). What is the most likely diagnosis and the most appropriate next investigation?

Explanation

## Clinical Presentation of Massive PE **Key Point:** This patient presents with the classic triad of massive pulmonary embolism: 1. **Acute hemodynamic collapse** (syncope, hypotension BP 88/56) 2. **Right ventricular strain** (JVD, RV heave, elevated troponin) 3. **Characteristic ECG changes** (sinus tachycardia, T-wave inversion V1–V4 = RV strain pattern) **High-Yield:** Troponin elevation in the setting of acute dyspnea + hemodynamic instability + RV strain pattern is NOT myocardial infarction until proven otherwise — consider PE first. ## Differential Diagnosis: Syncope + Hemodynamic Collapse | Feature | Massive PE | Acute MI | Acute Heart Failure | COPD Exacerbation | |---------|-----------|----------|-------------------|-------------------| | **Syncope** | Yes (RV failure) | Rare (unless cardiogenic shock) | No | No | | **JVD** | Yes (RV strain) | Variable | Yes (pulmonary edema) | No | | **RV heave** | Yes (RV dilatation) | No | No | No | | **Troponin elevation** | Yes (RV infarction from strain) | Yes (myocardial necrosis) | Mild/absent | No | | **ECG T-wave inversion V1–V4** | Yes (RV strain) | Yes (anterior STEMI) | No | No | | **CXR findings** | Clear or wedge opacity | Pulmonary edema | Pulmonary edema | Hyperinflation ± infiltrate | | **Risk factors** | Immobility, surgery, malignancy | Smoking, HTN, DM | HTN, CAD, cardiomyopathy | Smoking, COPD | **Clinical Pearl:** The **absence of pulmonary edema on CXR** in a hemodynamically collapsed patient with elevated troponin strongly favors PE over acute MI or acute heart failure. Acute PE does not cause pulmonary edema unless there is massive RV infarction with acute right-to-left shunting. ## Why This Is Massive PE **Mnemonic: MASSIVE PE criteria** — **M**ean arterial pressure <65 mmHg, **A**cute RV dysfunction, **S**hock, **S**yncope, **I**ncreased troponin, **V**entricular arrhythmia, **E**levated BNP/NT-proBNP. This patient meets: - Syncope ✓ - Hypotension (MAP ~67 mmHg) ✓ - RV strain (JVD, heave, troponin elevation) ✓ - T-wave inversion V1–V4 (RV ischemia) ✓ ## Diagnostic Algorithm for Suspected Massive PE ```mermaid flowchart TD A[Syncope + Hypotension + RV strain pattern]:::outcome --> B{Hemodynamically STABLE enough for CT?}:::decision B -->|Yes - SBP >90, no shock| C[CTPA]:::action B -->|No - Shock, severe hypotension| D[Bedside TTE]:::action D --> E{RV dilatation + RV:LV >0.9?}:::decision E -->|Yes| F[Massive PE confirmed]:::outcome E -->|No| G[Consider other diagnoses]:::outcome C --> H[Confirms PE]:::outcome F --> I[Thrombolysis or embolectomy]:::urgent ``` **High-Yield:** In a hemodynamically unstable patient with suspected massive PE, **do NOT delay treatment for CTPA**. Bedside echocardiography showing RV dilatation (RV:LV ratio >0.9) is sufficient to initiate thrombolysis or embolectomy. ## Why Each Option Is Wrong **Option A (Acute MI):** While troponin is elevated and T-waves are inverted, the clinical context is wrong: - Syncope is rare in acute MI unless cardiogenic shock (late finding). - RV heave and JVD suggest RV dysfunction from acute afterload (PE), not primary myocardial necrosis. - CXR is clear (no pulmonary edema), which is atypical for acute MI with hemodynamic collapse. - Coronary angiography in a patient with massive PE risks catastrophic deterioration during transport and sedation. **Option C (Acute Heart Failure):** Acute decompensated heart failure would present with: - Pulmonary edema on CXR (absent here). - Orthopnea, PND (not mentioned). - S3 gallop (not mentioned). - Gradual onset (not sudden syncope). **Option D (COPD Exacerbation):** COPD exacerbation does not cause: - Syncope or hemodynamic collapse. - RV heave or JVD (unless chronic cor pulmonale, which develops over time). - Troponin elevation. - T-wave inversion in V1–V4 (acute RV strain pattern).