Evidence-based carotid artery–based interventions for stroke risk reduction

Abstract

Approximately 800,000 individuals still experience a stroke in the United States each year. Despite a relative rate reduction of 37% over the last decade, in 2009, stroke still caused 1 of every 19 deaths (ranks only behind heart disease, cancer, and chronic lower respiratory disease). It remains the leading cause of serious long-term disability, with a staggering economic toll (estimated $38.6 billion in 2009). Driven by trends such as the aging population and rise in the metabolic syndrome, projections show that by 2030 an additional 4 million people will have had a stroke, a 22% increase in prevalence from 2013. Evidence supports a multitude of risk factors for stroke: age, high blood pressure, diabetes mellitus, cardiac dysrhythmias, hyperlipidemia, smoking, physical inactivity, genetics, chronic kidney disease, sleep apnea, prior stroke, and extracranial carotid artery occlusive disease. Great attention over the past few decades to modifiable risk factors such as hypertension likely underlies trends in stroke rate reductions. It is important to recognize that in the totality of modifiable risk factors for stroke, an asymptomatic high-grade carotid stenosis holds a relative risk of approximately 2.0. This is about the same or less than other factors such as cigarette smoking, hypertension, diabetes, high-density lipoprotein (HDL) o35 mg/dL, nonvalvular atrial fibrillation, sickle cell disease, oral contraceptive use, periodontal disease, and physical inactivity. Thus, to overly focus on a carotid stenosis without addressing other medical issues ignores important opportunities for stroke risk reduction. The diversity of risk factors for cerebrovascular accidents reflects the variety of underlying pathophysiologies for death of brain tissue. Approximately 15% of strokes are hemorrhagic, and the remainder are primarily ischemic. Surgeons were drawn into the field by mechanistic links between extracranial carotid artery atherosclerotic disease and thromboembolism from these lesions to the brain, leading to ischemia and infarction (Fig 1). Links between the extracranial carotid and stroke were first made by the Nobel laureate Egas Moniz in the 1920s. Several pioneers (C. Miller Fisher, Michael DeBakey, Felix Eastcott, Sir George Pickering, and Charles Rob) then moved this pathophysiological knowledge forward toward surgical therapy in the 1950s, and the carotid endarterectomy (CEA) operation evolved into the most commonly performed major vascular procedure in the world in subsequent decades. Extracranial carotid artery stenosis underlies approximately 1 in 4 strokes. Approximately 100,000 open CEA