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Abstract
In patients with severe left ventricular hypertrophy (LVH), but no significant coronary
artery disease (CAD), acute lowering of diastolic blood pressure (DBP) to less than
85 mm Hg is reported to result in a 26% fall in coronary blood flow and an increase
in myocardial oxygen demand; S-T segment and T-wave changes in the ECG are observed
when DBP is acutely lowered to the 70s in these patients. In the presence of good
resting left ventricular function, acute lowering of DBP to the 60s in well-controlled
hypertensives on a β-blocker, with either CAD or LVH, results in a mean increase of
about 20% in ventricular ejection fraction. By contrast, patients with a combination
of CAD and LVH experience a mean 6% fall in ejection fraction implying poor left ventricular
functional reserve. In low risk populations, which exclude patients with severe ischaemia,
diabetics and smokers, the lower the DBP the fewer the number of myocardial infarctions.
However, in heterogeneous hypertensive populations which include high risk patients,
such as ischaemics and diabetics (e.g. the MRFIT population), there is a strong U-
or J-curve relationship between DBP and CAD deaths. Meta-analysis of high quality
studies involving heterogeneous populations has shown that the U- or J-point is at
84 mm Hg and probably relates to high risk patients with ischaemia and/or LVH. Recent
data from the Framingham group indicate that the patients most at risk are those with
a combination of CAD and LVH: these patients showed a marked U-shaped curve with the
U- or J-point at about 85-89 mm Hg DBP. These results indicate that in hypertensive
patients with LVH and CAD, it would be prudent to reduce the DBP to the mid-80s and
not lower. It may prove sensible to use an agent which effectively reverses LVH and
improves coronary flow reserve: ACE inhibitors perform well in this respect.