Choice of Imaging Modality in the Assessment of Coronary Artery Disease Risk in Extreme Obesity

Abstract

) occurs in 1 in 20 American adults, and this population is especially at risk of poor health out­comes and increased cost of health care (2). CAD and its risk factors including diabetes mellitus, high blood cholesterol, and high blood pressure increase across weight classes (3,4). It is therefore of utmost importance that accurate risk assessment and stratification is able to be performed in this population at risk for greater morbidity and mortality from CAD.Despite as increased risk, evaluation of CAD in the EO population presents unique challenges. Symptoms con­cerning for CAD, such as dyspnea and reduced exercise tolerance, occur at a high frequency in those with extreme obesity with or without the presence of significant CAD (5), and may lower the sensitivity and specificity of the history and physical exam. In a cohort of class 2 and 3 obesity, dyspnea climbing two flights of stairs occurred in 69–87% and with bathing or dressing in 12–24% of patients (5). Determining the etiology of reduced exercise tolerance in this cohort is further confounded by increased prevalence of sedentary lifestyle as well as arthritis, which occurs in 44% of those with class 3 obesity (4). Assessment of symptoms can be further complicated by the increased incidence of chest pain with exertion (5) as well as left ventricu­lar (LV) hypertrophy and repolarization abnormalities on electrocardiogram (6). Incident obstructive sleep apnea, which occurs in 50% of the EO population (7), can masquerade as systolic heart failure with nocturia, lower extremity edema, and paroxysmal nocturnal dyspnea (8).Given these limitations to the history and physical exam, cardiovascular imag­ing is a vital modality to objectively and quantitatively characterize CAD risk. However, common techniques to assess CAD are often limited by body mass of individuals with extreme obes­ity (9). Although advances in imaging techniques have improved the accuracy and lessened the artifacts previously seen in class 1 and 2 obesity, few stud­ies have included significant numbers of extremely obese patients (2). Better patient care and resource allocation when assessing CAD in extreme obesity require an understanding of the limita­tions and advantages of various imaging modalities.It is evident that the risks of CAD are elevated in the EO, but the signs and symptoms concerning for CAD may be even more common and not neces­sarily related to CAD; this requires a knowledgeable approach to the evalu­ation of CAD in EO. In advanced obesity, a multidisciplinary approach is frequently necessary to discern the etiol­ogy of possible cardiac symptoms and to make a timely diagnosis. Cardiac assess­ment in the extreme obese population represents well the current challenge of appropriate resource allocation and utilization of technological advances in patient care. The following is a detailed review of imaging options and the cur­rent literature to assist the physician and researcher in care of this unique patient population as well as highlight needed future investigations.