ACC = American College of Cardiology; AHA = American Heart Association; ACEI = angiotensin-converting enzyme inhibitor; ARB = angiotensin II receptor blocker; BP = blood pressure; CHD = coronary heart disease; CKD = chronic kidney disease; CV = cardiovascular; DHA = docosahexaenoic acid; DM = diabetes mellitus; EPA = eicosapentaenoic acid; FDA = Food and Drug Administration; HbA1C = glycated hemoglobin; HDL-C = high-density lipoprotein cholesterol; HF = heart failure; hsCRP = high-sensitivity C-reactive protein; HTN = hypertension; LDL-C = low-density lipoprotein cholesterol; LVH = left ventricular hypertrophy; MetS = metabolic syndrome; MI = myocardial infarction; PCI = percutaneous coronary intervention; PSS = psychosocial stress; RR = relative risk; TZD = thiazolidinedione
A paradigm shift, the seeds of which were planted decades ago, is now in full bloom and is drastically altering the way in which we diagnose and treat stable coronary heart disease (CHD). The traditional and intuitively logical
plumbing paradigm hypothesized that the likelihood of major adverse cardiovascular (CV) events, such as myocardial infarction (MI) and CV death, were directly related to the angiographic severity of the atherosclerotic stenoses. Under this paradigm, the definitive means of favorably altering the prognosis of patients with CHD was to eliminate the angiographically significant stenoses with revascularization procedures, namely coronary artery bypass graft surgery and percutaneous coronary intervention (PCI). Despite the inherent commonsense plausibility of this theory, the prospective trials have repeatedly shown that revascularization procedures improve neither the short- nor long-term prognosis of patients with stable CHD, except for those with high-grade left main stenosis or severe proximal 3-vessel disease.
1Among the culprit lesions that cause acute coronary syndromes, studies indicate that only about 15% have a luminal diameter stenosis greater than 70% immediately before the rupture and thrombosis that precipitate the acute arterial occlusion.
1 When viewed in this light, it is not surprising that the revascularization of 1 or more high-grade lesions does not lower the risks of MI or death for a patient with stable CHD. A recent meta-analysis of all 17 randomized trials that compared PCI with medical therapy in patients with stable CHD showed that, although revascularization improves angina, it does not alter the incidence of MI or death compared with aggressive medical therapy alone
1-3 (). Impressively, in the COURAGE trial (for expansion of all trial names, see Glossary), optimal medical therapy improved anginal status during the course of the 5-year trial to such a degree that, by study end, 70% of patients were angina free, which was equivalent to the proportion free from angina in the PCI plus optimal medical therapy arm of the study.
3 Similarly, the BARI 2D study found that aggressive medical therapy in patients with type 2 diabetes mellitus (DM) was as effective as elective coronary revascularization for reducing death and adverse CV events.
4In the new paradigm, arterial inflammation and endothelial dysfunction, which play central roles in determining the prognosis and angina status of patients with stable CHD, are best treated with an aggressive multidrug regimen coupled with therapeutic lifestyle changes in an effort to normalize the major CV risk factors (eg, dyslipidemia, hypertension [HTN], smoking, sedentary
lifestyle, obesity, hyperglycemia). This strategy neutralizes the atherogenic milieu and reduces vascular inflammation, thereby markedly decreasing the risk of adverse CV events and the need for revascularization procedures.
5Atherosclerosis typically develops, progresses, and festers for decades in a clinically silent fashion; however, when it finally manifests itself, it often does so as a life-threatening catastrophe, such as sudden cardiac arrest, MI, or stroke, often in persons who previously would have been classified as at low or intermediate risk by the Framingham Risk score.
6 Thus, the SHAPE national task force has endorsed the screening of asymptomatic middle-aged patients with either computed tomography for coronary artery calcification or ultrasonography for carotid artery plaque.
7 Indeed, the coronary artery calcium score has proved to be superior to the Framingham Risk score for identifying persons at risk of CHD.
8Although CHD remains highly prevalent among westernized populations and continues to be the leading cause of death in the United States, the age-adjusted CV death rates have decreased almost 50% during the past 25 years.
9 Recent studies indicate that improvements in CV risk factors, especially cholesterol, HTN, and cigarette smoking, have accounted for most of this dramatic decrease in risk of CV death.
9 Although many of the major CV risk factors (eg, HTN, DM, dyslipidemia) are influenced by a person's genetic constitution, most studies have not found widespread genetic screening to be practical or clinically useful for identifying those at high risk of CHD.
10 Indeed, the INTERHEART study suggests that the risk of MI is almost entirely attributable to modifiable CV risk factors.
11 This large case-control study identified 9 modifiable risk factors, which in aggregate accounted for more than 90% of the variability of acute MI. These risk factors were dyslipidemia, smoking, HTN, psychosocial stress (PSS), DM, increased waist-hip ratio, physical inactivity, poor diet, and abstinence from alcohol. These CV risk factors often cluster together, creating a synergistic effect that multiplies risk of MI. Randomized trial data and clinical experience indicate that aggressive multimodal therapy targeting the modifiable CV risk factors in a reasonably adherent patient dramatically reduces and by some accounts almost eliminates the occurrence of adverse CV events.
12 Nevertheless, recent statistics suggest that the United States, with its twin epidemics of obesity and DM (sometimes referred to as
diabesity), may soon see a reversal in the dramatic progress made against CV disease in recent decades.
13 Obesity also accounts for the increasing prevalence of younger patients presenting with acute MI.
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