ReviewObesity and Coronary Artery Disease: Evaluation and Treatment
Section snippets
Epidemiology
The most commonly used anthropometric tool to classify obesity is body mass index (BMI), the ratio of total body weight in kilograms divided by the height in meters squared (kg/m2). The different classes of obesity are described in Table 1. Obesity is an independent risk factor for cardiovascular (CV) disease (CVD).1, 2 It also increases the incidence of traditional CV risk factors like hypertension, dyslipidemia, and diabetes mellitus, leading to a greater incidence of ischemic stroke and
Obstructive Coronary Artery Disease and Obesity
The Pathobiological Determinants of Atherosclerosis in Youth (PDAY) study, based on postmortem examination of arteries from young individuals who died from accidental injuries, homicides, or suicides, was landmark in understanding the relationship between atherosclerosis and obesity.19 This study documented that obesity in adolescents and young adults accelerates the progression of atherosclerosis decades before the appearance of clinical manifestations, and that high BMI correlates with more
Electrocardiogram
The electrocardiogram (ECG) is modified by structural changes related to obesity. The heart is displaced by diaphragmatic elevation in the prone position. Increased circulating blood volume leads to increased stoke volume, which increases cardiac output and results in left chamber hypertrophy.22 Subcutaneous and epicardial fat influences ECG because of the increased distance between the heart and the electrodes.1 These ECG findings are well defined in the landmark study in 1029 obese patients (
Treadmill stress test
Standard stress test performance is limited in obesity patients by several factors, which often make other approaches more useful. ECG modification might limit accurate interpretation. Aerobic capacity is diminished because of pulmonary dysfunction, orthopaedic limitations, and LV diastolic dysfunction. Many obese patients fail to achieve the 80%-85% age-predicted heart rate needed for diagnostically-valid results.46, 47 Chronotropic competence is reduced, with peak heart rate, heart rate
Single photon emission computed tomography
Single photon emission computed tomography has a sensitivity of 87% and specificity of 73%.59, 60 The main pitfalls in obesity remain attenuation artifacts. Technetium sestamibi is the marker of choice in the obese because of greater energy emission, which generates better images.61 The down side is a higher rate of false positive results in severely obese patients.62 Attenuation protocols limit the rate of false positivity.63
Positron emission tomography-computed tomography
Positron emission tomography (PET)–computed tomography rubidium has a
Non-ST-elevation myocardial infarction and obesity
Obesity is the strongest factor associated with non-ST-elevation myocardial infarction (NSTEMI) at a younger age, followed by tobacco use.66 For overweight and obesity classes 1, 2, and 3, the mean age for NSTEMI was 3.5, 6.8, 9.4, and 12.0 years earlier compared with normal weight individuals, respectively.
ST-elevation myocardial infarction and obesity
A recent study using cMRI determined that ST-elevation myocardial infarction (STEMI) infarct size in patients with BMI ≥ 25 was significantly smaller vs normal weight patients67 but only 5
In-hospital Events After PCI
The CathPCI Registry examined in-hospital complications of 83,861 severely obese patients.101 After multivariable adjustment, obesity was independently associated with a greater mortality rate (OR, 1.14) and a lower bleeding rate (OR, 0.80).101 Although severe obesity affects weight-based dosing protocols for unfractionated heparin,102 this population is underrepresented or even excluded from major trials.102 It remains unclear whether one should use the maximum dose recommended or weight-based
Long-term Follow-up After PCI
Low BMI patients tend to have more events after PCI than obese patients.105, 106 A study of 23,181 patients from 11 prospective PCI studies used a BMI of 22.5-24.9 as the reference category: the risk of major CV events was increased among patients with a lower BMI (HR, 1.52 for BMI < 18.5) and declined among patients with a higher BMI (eg, 0.78 for a BMI ≥30.0).107 A recent meta-analysis of 10 post-PCI and 12 post-CABG studies confirmed these findings.108 This obesity paradox seems to wane when
Perioperative mortality
Obesity has been inconsistently associated with an increased in-hospital mortality after CABG. An analysis of the Society of Thoracic Surgeons' database (559,004 patients who underwent isolated CABG between 1997 and 2000118) showed an increased risk of in-hospital mortality in moderately obese (n = 42,060; BMI = 35-39.9; OR, 1.21) and severely obese patients (n = 18,735; BMI ≥ 40; OR, 1.58) compared with subjects with a BMI of 18.5-34.9. These results contrasted with previous studies that found
Conclusions
Patients with varying degrees of excess weight and obesity are becoming increasingly treated with PCI and CABG surgery. For PCI, miniaturization of equipment, radial approach, and weight-based anticoagulation minimize acute risks of vascular complications and bleeding and accelerate ambulation and early hospital discharge. The use of DES and stronger antiplatelet agents have also optimized mid- and long-term outcomes. For obese patients who require surgical revascularization, CABG remains an
Acknowledgements
David Garcia-Labbé and Emmeline Ruka contributed equally to this work.
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