Over the last three decades there is an increasing number of investigators and meta-analyses focusing on the dangers of lowering blood pressure below certain levels. Several studies such as Invest, Ontarget, Value and TNT showed a significant decrease in cardiovascular morbidity and mortality by lowering blood pressure levels. However, blood pressure decrease below a certain level had exactly the opposite effect. The increase of cardiovascular morbidity and mortality was attributed to the excessive reductions in blood pressure which may explain why in major clinical trials blood pressure below certain levels increases cardiovascular adverse events mainly in patients with coronary heart disease. In these patients a fall in diastolic blood pressure might lower perfusion pressure distal to a stenosis below a critical level at which autoregulation is effective. This phenomenon led the European Society of Hypertension to propose a "J-shaped curve" relationship between blood pressure and cardiac morbidity and mortality, whereby lowering blood pressure below a critical point is no longer beneficial and possibly even deleterious. The challenge is to better define the limits of intervention and to define groups of people who are particularly vulnerable to over-aggressive lowering of blood pressure
