Pulse pressure and cardiovascular risk.

Numerous studies have shown that increases in diastolic (DBP) and systolic (SBP) blood pressure are positively associated with cardiac events. Since DBP typically varies by smaller amounts, it has historically been the blood pressure value used most often to assess the risk of cardiovascular disease. Further studies have indicated, however, that SBP continues to increase proportionally with age, while DBP levels off. New data have emerged which suggest that DBP can no longer be valued as a reliable predictor of cardiovascular events and may even be diagnostically misleading. Normal levels of DBP can be indicative of a combination of an increase in peripheral vascular resistance (which elevates DBP) with an increase in arterial stiffening (which decreases DBP). These two phenomena 'cancel' each other out; the underlying risk factors are disguised by the apparent normalcy of the DBP reading. DBP is even less of an indicator in older adults, where the prevailing form of hypertension is isolated systolic hypertension and the most common cause is large-artery stiffness. Since arterial stiffening causes SBP to increase and DBP to decrease, the gap between the two, pulse pressure (PP), may be the best predictor of cardiac events for all the blood pressure values. Several studies have confirmed that subjects with the widest PP have the greatest risk of mortality. Pulse pressure has also been observed to be a significant and independent indicator of myocardial infarction. Furthermore, compelling evidence has emerged that PP is a strong indicator of cardiovascular risk even among normotensive individuals.