J-shaped curves.
Antihypertensive treatment trials with more than 14,000 treated patients have indicated a J- or U-shaped relationship between achieved blood pressure (BP) and coronary heart disease (CHD) risk. However, similar studies involving more than 16,000 treated patients have not found such a relationship, only a rather flat response. Analysis bias may partly be responsible for the different results, but the findings of a non-linear relationship do appear to be significant in several of the studies. Pre-existing myocardial ischaemia (with or without symptoms) may explain some of the cases with increased CHD risk at low BP levels, but not others, However, myocardial ischaemia may still be a cause of the increased risk when BP is excessively lowered due to reduced myocardial autoregulatory reserve. In the long term it would appear reasonable to 'normalise' the BP as much as is possible. However, the question is whether a more gradual reduction would be advisable in some cases. As yet we do not know in which patients this would be so, hence at present no change of treatment practices are recommended.
Department of Medicine, Gothenburg University, Ostra Hospital, Sweden.
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Wilhelmsen
D015982:Bias; D002561:Cerebrovascular Disorders / Q000209:etiology*; D003327:Coronary Disease / Q000150:complications / Q000209:etiology*; D006801:Humans; D006973:Hypertension / Q000150:complications* / Q000628:therapy; D012307:Risk Factors