Understanding Hypertension

Cardiovascular Disease Risk Factors

These recommendations are presented in abbreviated form. Readers should refer to the complete guideline document¹ for a detailed discussion of each of the following topics.

Historically, therapeutic intervention thresholds for the treatment of cardiovascular risk factors Such as blood pressure, blood cholesterol and blood sugar have been based on variably arbitrary cut-points of the individual risk factors. Because risk factors cluster in individuals and there is a graded association between each risk factor and overall cardiovascular risk, the contemporary approach to treatment is to determine the threshold, at least for cholesterol and blood pressure reduction, based on the calculation of estimated coronary or cardiovascular (coronary plus stroke) risk over a defined, relatively short-term (e.g. 5- or 10-year) period.

On this basis, a classification using stratification for total cardiovascular risk is suggested in Table 2.

Table 2

	Blood pressure (mmHg)
Other risk factors and disease history	Normal: SBP 120–129 or DBP 80–84	High normal: SBP 130–139 or DBP 85–89	Grade 1: SBP 140–159 or DBP 90–99	Grade 2: SBP 160–179 or DBP 100–109	Grade 3: SBP > 180 or DBP > 110

No other risk factors	Average risk	Average risk	Low added risk	Moderate added risk	High added risk
1-2 risk factors	Low added risk	Low added risk	Moderate added risk	Moderate added risk	Very high added risk
3 or more risk factors or TOD or diabetes	Moderate added risk	High added risk	High added risk	High added risk	Very high added risk
ACC	High added risk	Very high added risk	Very high added risk	Very high added risk	Very high added risk

ACC, associated clinical conditions; TOD, target organ damage; SBP, systolic blood pressure; DBP, diastolic blood pressure.

Table 3 (below) indicates the most common risk factors, target organ damage, diabetes and associated clinical conditions which are used to stratify risk.

Risk factors for cardiovascular disease used for stratification	Target organ damage (TOD)	Diabetes mellitus	Associated clinical conditions (ACC)
Levels of systolic and diastolic BP Men > 55 years Women > 65 years Smoking Dyslipedaemia (total cholesterol > 6.5 mmol/l, > 250 mg/dl*. or LDL-cholesterol > 4.4 mmol/l, > 155 mg/dl, or HDL-cholesterol M < 1.0, W < 1.2 mmol/l, M < 40, W < 48 mg/dl) Family history of premature cardiovascular disease (at age < 50 years M, < 65 years W) Abdominal obesity (abdominal circumference M ≥ 102, W ≥ 88 C-reactive protein ≥ 1mg/dl	Left ventricular hypertrophy (electrocardiogram: Sokolow-Lyons >38mm; Cornell >2440*ms; echocardiogram: LVMI M ≥125 W ≥110g/m²) Ultrasound evidence of arterial wall thickening (carotid IMT ≥ 0.9mm) or atherosclerotic plaque Slight increase in serum creatinine (M 115-133, W107-124, µmol/m; M1.3-1.5, W 1.2-1.4 mg/dl) Microalbuminuria (30-300 gm/24 h; albumin-creatinine ratio M ≥ 22, W ≥ 31 mg/g, M ≥ 2.5, W ≥ 3.5 mg/mmol)	Fasting plasma glucose 7.0 mmol/l (126 mg/dl) Postprandial plasma glucose > 11.0 mmol/l (198 mg/dl)	Cerebrovascular disease: ischaemic stroke; cerebral haemorrhage; transient ischaemic attack; Heart disease: myocardial infarction; angina; coronary revascularization; congestive heart failure Renal disease: diabetic nephropathy; renal impairment; (serum ceratinine M > 133, W > 124 µmol/l; M > 1.5, W > 1.4 mg/dl) proteinuria (> 300 mg/24h ) Peripheral vascular disease Advanced retinopathy: haemorrhages or exudates papilloedema
M, men; W, women; LDL, low density lipoprotein; HDL, high density lipoprotein; LVMI, left ventricular mass index; IMT, intima-media index; * Lower levels of total and LDL-cholesterol are known to delineate risk, but they were not used in the stratification.

Searching for target organ damage

Due to the importance of target organ damage in determining the overall cardiovascular risk of the hypertensive patient (see Tables 2 and 3 above), evidence of organ involvement should be sought carefully. Recent studies have shown that without ultrasound cardiovascular investigations for left ventricular hypertrophy and vascular (carotid) wall thickening or plaque, up to 50% of hypertensive subjects may be mistakenly classified as at low or moderate added risk, whereas presence of cardiac or vascular damage places them within a higher risk group. Echocardiography and vascular ultrasonography can therefore be considered as recommended tests, particularly in patients in whom target organ damage is not discovered by routine investigations including an electrocardiogram. Likewise, searching for microalbuminuria is recommended, because of the mounting evidence that it may be a sensitive marker of organ damage, not only in diabetes but also in hypertension.

References:
1. 2003 European Society of Hypertension–European Society of Cardiology guidelines for the management of arterial hypertension. Journal of Hypertension 2003, 21:1011–1053. Available at: http://www.eshonline.org/

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