What is the most likely cause of hypotension and tachycardia with a pansystolic murmur radiating to the right sternal border in a patient with a history of coronary artery disease (CAD) 5 days after percutaneous coronary intervention (PCI) for acute coronary syndrome (ACS)?

Interventricular Septal Rupture (Ventricular Septal Defect)

The most likely diagnosis is interventricular wall rupture (ventricular septal defect), given the pansystolic murmur radiating to the right sternal border occurring 5 days post-PCI in a patient with acute coronary syndrome who now presents with hypotension and tachycardia. 1

Clinical Presentation and Timing

• Mechanical complications of myocardial infarction, including ventricular septal rupture, typically occur within the first week post-MI, with peak incidence between days 3-7 1
• The presentation of hypotension and tachycardia indicates hemodynamic compromise from acute left-to-right shunting through the septal defect 1
• Cardiogenic shock develops in up to 3% of NSTE-ACS patients during hospitalization and has become the most frequent cause of in-hospital mortality 1

Distinguishing Features by Murmur Location

The key distinguishing feature is the murmur radiation pattern:

• Ventricular septal rupture produces a harsh pansystolic murmur that radiates to the right sternal border due to the left-to-right shunt across the interventricular septum 1
• Mitral regurgitation from papillary muscle rupture produces a pansystolic murmur that radiates to the axilla, not the right sternal border 1
• Free wall rupture typically presents with sudden cardiovascular collapse, pericardial tamponade, and electromechanical dissociation rather than a new murmur 1
• Pseudoaneurysm does not typically produce a pansystolic murmur and presents with a more subacute course 1

Pathophysiology and Risk Factors

• Ventricular septal rupture occurs when transmural infarction leads to necrosis of the interventricular septum, creating a communication between the left and right ventricles 1
• Emergency CABG is recommended in patients with mechanical complications of MI, including ventricular septal rupture, mitral valve insufficiency from papillary muscle rupture, or free wall rupture 1
• More than two-thirds of patients with cardiogenic shock complicating ACS have three-vessel coronary artery disease 1

Immediate Management Approach

• Immediate coronary angiography is indicated for patients presenting with cardiogenic shock to identify the coronary anatomy and mechanical complications 1
• Emergency surgical repair is the definitive treatment for ventricular septal rupture, as medical management alone carries extremely high mortality 1
• If coronary anatomy is not suitable for PCI or if mechanical complications are identified, patients should undergo emergent CABG with concurrent septal defect repair 1
• Intra-aortic balloon counterpulsation or mechanical circulatory support (extracorporeal membrane oxygenation or implantable LV assist devices) may be considered as a bridge to surgery in selected patients 1

Diagnostic Confirmation

• Transthoracic echocardiography should be performed urgently to visualize the septal defect, assess shunt severity, and evaluate ventricular function 1
• Doppler echocardiography will demonstrate turbulent flow across the interventricular septum 1
• Right heart catheterization may show an oxygen saturation step-up in the right ventricle, confirming left-to-right shunting 1

Common Pitfall

The critical error would be attributing the murmur to mitral regurgitation without considering the radiation pattern—mitral regurgitation radiates to the axilla, while ventricular septal rupture radiates to the right sternal border due to the anatomic location of the defect 1