SCAD

SCAD
Name	SCAD
Synonyms	Spontaneous coronary artery dissection
Field	Cardiology
Symptoms	Chest pain, shortness of breath, myocardial infarction
Complications	Heart failure, ventricular arrhythmia, cardiac arrest
Onset	Sudden
Risks	Fibromuscular dysplasia, pregnancy, connective tissue disease
Diagnosis	Coronary angiography, intravascular ultrasound
Treatment	Conservative management, percutaneous coronary intervention, coronary artery bypass surgery
Medication	Beta blocker, aspirin
Prognosis	Variable; high rate of recurrence
Frequency	Underdiagnosed; leading cause of myocardial infarction in young women

SCAD. It is a rare, life-threatening condition characterized by a spontaneous tear occurring within one or more layers of the coronary artery wall, not related to atherosclerosis or traumatic injury. This tear can create a false lumen that restricts blood flow, often leading to an acute coronary syndrome, myocardial infarction, or sudden cardiac arrest. While it can affect anyone, it is disproportionately identified as a leading cause of heart attacks in younger women and individuals with few traditional cardiovascular disease risk factors. The understanding of its pathophysiology and optimal management has evolved significantly through research led by institutions like the Mayo Clinic and registries such as the Vancouver General Hospital-based cohort.

Overview

SCAD involves a separation within the coronary artery wall that typically occurs in the absence of any external trauma or iatrogenic cause during procedures like percutaneous coronary intervention. This event disrupts normal coronary circulation, often resulting in myocardial ischemia and damage to the myocardium. The condition is distinct from atherosclerotic coronary artery disease and is frequently associated with specific underlying arteriopathies. Landmark studies published in journals like Circulation and the Journal of the American College of Cardiology have been instrumental in defining its clinical profile. Diagnosis is primarily achieved through advanced imaging techniques during cardiac catheterization.

Causes and risk factors

The precise etiology of SCAD remains incompletely understood but is strongly linked to underlying vulnerabilities in the arterial wall. A predominant association is with fibromuscular dysplasia, a non-inflammatory arteriopathy often affecting the renal artery and carotid artery, which is found in a high percentage of patients. Hormonal and physical stress factors are also significant, with many cases occurring in the postpartum period or in association with intense emotional stress or physical exertion. Other predisposing conditions include inherited connective tissue disease such as Marfan syndrome, Ehlers-Danlos syndrome, and systemic lupus erythematosus. Traditional risk factors for atherosclerosis, such as hypertension and dyslipidemia, are less commonly present.

Diagnosis

Accurate diagnosis is critical and hinges on coronary angiography, which may reveal characteristic findings like multiple radiolucent lumens or diffuse stenosis. However, angiography can sometimes be ambiguous, leading to the increased use of adjunctive intracoronary imaging modalities. Intravascular ultrasound and optical coherence tomography provide high-resolution views of the arterial wall layers, allowing visualization of the intramural hematoma or dissection flap. These tools are essential for differentiating SCAD from other causes of acute coronary syndrome, such as plaque rupture or coronary embolism. Diagnostic protocols have been refined through work at centers like the University of British Columbia and Cedars-Sinai Medical Center.

Treatment and management

Management strategies differ markedly from those for atherosclerotic disease and often favor a conservative, medication-first approach. Initial stabilization typically involves agents like beta blockers to reduce myocardial oxygen demand and heart rate, and aspirin for antiplatelet effect. The use of potent antiplatelet drugs like clopidogrel or ticagrelor is debated, and thrombolytic therapy is generally contraindicated. Percutaneous coronary intervention carries a high risk of complications, such as extension of the dissection, and is typically reserved for patients with ongoing ischemia or compromised flow in a major epicardial coronary artery. In severe cases, coronary artery bypass surgery may be necessary.

Prognosis and complications

The in-hospital prognosis is generally good with appropriate management, but the condition carries a substantial long-term risk of major adverse cardiac events. Common complications include recurrent SCAD, which occurs in a significant minority of patients within the first few years, progressive heart failure due to myocardial infarction, and life-threatening ventricular arrhythmia. The healing process of the dissected artery is often spontaneous, monitored through follow-up imaging. Long-term care focuses on blood pressure control, avoidance of extreme physical exertion and hormone therapy, and management of associated conditions like fibromuscular dysplasia. Patient support networks, including the SCAD Alliance, play a crucial role in education and research advocacy.

Epidemiology

SCAD is an underdiagnosed cause of acute myocardial infarction, accounting for a substantial proportion of cases in women under 50 years of age, with some studies suggesting it is responsible for up to 35% of such events. It is less common in men and older populations. The true incidence is difficult to ascertain due to historical diagnostic challenges, but increased awareness and improved imaging are leading to more frequent identification. Large multicenter registries in North America and Europe continue to refine epidemiological understanding. Predisposing factors like the postpartum state and fibromuscular dysplasia highlight specific at-risk demographics distinct from those with traditional coronary artery disease.

Category:Cardiovascular diseases Category:Medical emergencies