LETTER TO THE EDITOR
Hypertension and the prothrombotic state
Sunil Nadar, MRCP and
Gregory Y. H. Lip, MD, FRCP
University Department of Medicine, City Hospital, Birmingham B18 7QH United Kingdom
G.Y.H.LIP{at}bham.ac.uk
We read with interest the report by Pini et al. (1) that stated patients with isolated systolic hypertension had a higher prevalence of cardiac hypertrophy and carotid atherosclerosis than did those with diastolic hypertension. Indeed, hypertensive left ventricular hypertrophy is the most evident manifestation of hypertensive target organ damage, and such patients are at particularly high risk for strokes and heart attacks. We would like to propose an additional interpretation of their important observations.
Despite the vessels being exposed to high pressures, the main complications of hypertension (strokes, myocardial infarction) are, paradoxically, thrombotic rather than hemorrhagic — the so-called thrombotic paradox of hypertension or the Birmingham paradox (2). The findings by Pini et al. (1) would actually strengthen our view that hypertension confers a prothrombotic or hypercoagulable state by fulfilling the three different components of Virchow’s triad for thrombogenesis. With regard to the latter, there ought to be changes in the blood flow, changes in the vessel wall, and changes in the blood constituents, for increased thrombogenesis. "Abnormal flow" is evident in hypertension, with blood vessels exposed to blood flow under high pressures, as well as abnormal coronary flow reserve and microcirculatory changes (3). We had previously reported abnormalities in prothrombotic factors, endothelial function, and platelet activation in patients with isolated systolic hypertension, comparable to that observed with systolic–diastolic hypertension (3–5).
The study by Pini et al. (1) certainly confirms the presence of "vessel wall abnormalities" with the high prevalence of cardiac hypertrophy and carotid atherosclerosis. Furthermore, hypertensive patients with target organ damage (5) show evidence suggestive of an even greater prothrombotic state, which would contribute to the high risk of vascular complications in such patients.
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References
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1. Pini R, Cavallini C, Bencini F, et al. Cardiovascular remodelling is greater in isolated systolic hypertension in older adults: the Insufficenza Cardiaca negli Anziani Resienti (ICARE) a Dicomano Study. J Am Coll Cardiol. 2002;40:1283–1289[Abstract/Free Full Text]
2. Lip GYH. Hypertension and the prothrombotic state. J Hum Hypertens. 2000;14:687–690[CrossRef][Medline]
3. Lip GYH, Blann AD, Jones AF, Lip PL, Beevers DG. Relation of endothelium, thrombogenesis and hemorheology in systemic hypertension to ethnicity and left ventricular hypertrophy. Am J Cardiol. 1997;80:1566–1571[CrossRef][Medline]
4. Lip GYH, Blann AD, Beevers DG. Prothrombotic factors, endothelial function and left ventricular hypertrophy in isolated systolic hypertension compared with systolic–diastolic hypertension. J Hypertens. 1999;17:1203–1207[Medline]
5. Spencer CG, Gurney D, Blann AD, Beevers DG, Lip GY. Von Willebrand factor, soluble P-selectin, and target organ damage in hypertension: a substudy of the Anglo-Scandinavian Cardiac Outcomes Trial (ASCOT). Hypertension. 2002;40:61–66[Abstract/Free Full Text]
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