What is the role of ECG (electrocardiogram) and 2DECHO (2-dimensional echocardiogram) in patients with Deep Vein Thrombosis (DVT)?

Role of ECG and 2DECHO in Deep Vein Thrombosis

In patients with DVT, ECG and echocardiography are primarily indicated to assess for right ventricular dysfunction and pulmonary embolism complications rather than for the diagnosis of DVT itself. 1

ECG in DVT/PE

ECG has limited direct diagnostic value for DVT but can help identify complications such as pulmonary embolism:

• ECG has a sensitivity of 50-60% and specificity of 80-90% for diagnosing pulmonary embolism 2
• Common ECG findings in PE include:
  • T wave inversions in right precordial leads (V1-V4), suggesting right ventricular overload 2
  • QR pattern in V1 indicating acute right ventricular strain 2
  • S1Q3T3 pattern (S wave in lead I, Q wave and inverted T wave in lead III) 2
• ECG findings are more pronounced in massive PE but may be normal in up to 30% of confirmed PE cases 1

2D Echocardiography in DVT/PE

Echocardiography plays a crucial role in risk stratification and management decisions when PE is suspected:

Diagnostic Value

• In patients with hemodynamic instability and suspected PE, the absence of echocardiographic signs of RV overload or dysfunction practically excludes PE as the cause 1
• Echocardiography can identify:
  • Right ventricular hypokinesis (present in 90% of patients with significant perfusion defects) 1
  • Decreased collapsibility of the inferior vena cava (reported in 82% of patients with clinically important PE) 1, 3
  • McConnell sign: hypokinesis of the RV free wall with normal/hyperdynamic apex function (77% sensitive, 94% specific for acute PE) 1, 2, 3
  • 60/60 sign: pulmonary ejection acceleration time <60ms with tricuspid valve gradient <60mmHg 2

Prognostic Value

• Right ventricular dysfunction on echocardiography is associated with increased short-term mortality in hemodynamically stable patients 1
• An RV/LV diameter ratio >1.0 and TAPSE <16mm are associated with unfavorable prognosis 1
• Evidence of RV dysfunction is found in ≥25% of unselected patients with acute PE 1
• Patients with non-massive PE but with RV hypokinesis should be classified as having submassive PE, which carries higher risk 1

Clinical Applications

• In high-risk suspected PE (with shock or hypotension), echocardiography should be performed immediately to guide management 1
• In normotensive patients, echocardiography helps identify those at intermediate risk who may benefit from more intensive monitoring 1
• Echocardiography can detect right-to-left shunting through a patent foramen ovale, which increases risk of paradoxical embolism and stroke 1
• Echocardiography can identify right heart thrombi, which are associated with high early mortality 1

Combined Approach with Venous Ultrasound

• In patients with suspected PE, a combination of cardiac echocardiography and venous ultrasound increases diagnostic specificity 1
• When both echocardiography shows no RV dysfunction and venous ultrasound is normal, PE can be excluded with a high (96%) negative predictive value 1
• Compression ultrasonography (CUS) of lower extremities shows DVT in 30-50% of patients with confirmed PE 1, 3
• Finding a proximal DVT on CUS in a patient with suspected PE is sufficient to warrant anticoagulant treatment without further testing 1

Clinical Algorithm for Using ECG and Echocardiography in DVT

1. For patients with uncomplicated DVT without cardiopulmonary symptoms:

   • Routine ECG and echocardiography are not indicated 1

2. For patients with DVT and symptoms suggesting PE (dyspnea, chest pain, syncope):

   • Perform ECG to assess for signs of right heart strain 2
   • Consider echocardiography if:
     • Hemodynamic instability is present 1
     • There are clinical signs of right heart failure 1
     • Risk stratification is needed for treatment decisions 1

3. For patients with confirmed PE:

   • Echocardiography should be performed to assess RV function and guide risk stratification 1
   • Serial echocardiography can be used to monitor response to treatment 1

Important Considerations and Pitfalls

• Echocardiographic parameters have proved difficult to standardize, which may affect their positive predictive value for PE-related death 1
• A normal echocardiogram makes hemodynamically significant PE unlikely but cannot completely exclude the diagnosis 3
• Both underdiagnosis and overdiagnosis of PE are common in clinical practice 3
• ECG changes in PE can be subtle or nonspecific and should not be used in isolation to rule out PE 2
• In patients with suspected PE who cannot undergo CT angiography, a combination of clinical assessment, D-dimer, venous ultrasound, and echocardiography may be used 1