Reviews for Primary Care - Fall 2007 - (Page 37) The Renin-Angiotensin System and Cardiovascular Diseases Table 1 Hypertension Writing Group Definition and Classification of Hypertension Stage 1 Hypertension Occasional or intermittent BP elevations OR risk factors or markers suggesting early CVD* 1 risk factor present 0-1 None Stage 2 Hypertension Sustained BP elevations OR evidence of progressive CVD* Multiple risk factors present 2 Early signs present Stage 3 Hypertension Marked and sustained BP elevations OR evidence of advanced CVD* Multiple risk factors present 2 present with evidence of CVD Overtly present with or without CVD events Classification Normal Descriptive Category Normal BP or rare (BP Pattern and CVD BP elevations AND Status) no identifiable CVD* CVD Risk Factors† Early Disease Markers‡ Target Organ Disease§ None None None *BP elevations refer to levels 140/90 mm Hg. CVD designation is determined by the constellation of risk factors, early disease markers, and target organ disease. † Cardiovascular risk factors include increased age, elevated BP ( 140/90 mm Hg), overweight/obesity (body mass index 24 kg/m2), abdominal obesity, dyslipidemia, elevated fasting blood glucose (or insulin resistance or diabetes), smoking, family history of premature CVD, sedentary lifestyle, and elevated high-sensitivity C-reactive protein. ‡ Early disease markers defined according to system, eg, blood pressure (includes loss of nocturnal BP dipping, widened pulse pressure), cardiac (includes mild left ventricular hypertrophy, increased atrial filling pressure), vascular (includes increased central arterial stiffness, increased carotid intima-media thickness, endothelial dysfunction), renal (includes microalbuminuria, elevated serum creatinine), and retinal (hypertensive retinal changes). § Target organ damage and overt CVD defined according to system, eg, cardiac (includes moderate to severe left ventricular hypertrophy, symptomatic heart failure, myocardial infarction, angina pectoris, ischemic heart disease), vascular (includes peripheral arterial disease, carotid arterial disease, aortic aneurysm), renal (albuminuria, chronic kidney disease or end-stage renal disease), and cerebrovascular (stroke, transient ischemic attack). BP, blood pressure; CVD, cardiovascular disease. considered alongside indicators of target organ damage and cardiovascular risk47: Hypertension is a progressive cardiovascular syndrome arising from complex and interrelated etiologies. Early markers of the syndrome are often present before blood pressure elevation is observed; therefore, hypertension cannot be classified solely by discrete blood pressure thresholds. Progression is strongly associated with functional and structural cardiac and vascular abnormalities that damage the heart, kidneys, brain, vasculature and other organs, and lead to premature morbidity and death. The proposed Hypertension Writing Group definition and classification of hypertension is presented (Table 1). Notably, the ongoing Trial of Preventing Hypertension (TROPHY) study is investigating whether early RAS inhibitor treatment with an ARB in patients with prehypertension might prevent or delay the development of clinical hypertension.48 Baseline cardiovascular risk profiles of the 809 subjects enrolled in TROPHY showed that 96% of subjects had at least one additional cardiovascular risk factor, 81% had 2 or more, and 13% had 5 or more additional risk factors.49 These findings illustrate that in many patients, the risk of cardiovascular disease may begin to rise— due to risks such as early target damage—before BP reaches the current threshold for the diagnosis of hypertension. The potential benefits of early ARB treatment in protecting against RAS-induced organ damage in these patients will be of interest, although it is possible that the optimal time for intervention in the natural history of hypertension might be earlier than at the average age of 50 years studied in TROPHY. Conclusions The development of effective inhibitors of the RAS has led to a major step forward in our understanding of the pathophysiology of cardiovascular disease. Indeed, the importance of target organ damage, such as that caused by RAS activation, has been recognized in the new definition of hypertension proposed by the Hypertension Writing Group. Although ACE inhibitors and ARBs have provided an excellent starting point for therapies targeting the RAS, clinical trial evidence indicates that there remains VOL. 1 NO. 1 2007 REVIEWS FOR PRIMARY CARE 37
For optimal viewing of this digital publication, please enable JavaScript and then refresh the page. If you would like to try to load the digital publication without using Flash Player detection, please click here.