Prognostic significance of morning surge in blood pressure: which definition, which outcome?

The prognostic significance of morning surge in blood pressure (BP) remains obscure because the findings of the four prospective studies available ambulatory BP monitoring (ABPM) substudy of the Syst-Eur trial, the Jichii Medical School ABPM-wave1 study, the Bordeaux hypertensive cohort study, and the Ohasama study have generated conflicting results partly because of small number of events and differences in definitions, measurement conditions, target outcomes, and study populations. A large morning surge was associated with a significantly lower risk of total cardiovascular events in the Syst-Eur study. On the contrary, a large morning surge was associated with a significantly higher risk of total stroke events in the Jichii Medical School ABPM-wave1 study, and of total cardiovascular events in the Bordeaux hypertensive cohort study. The Ohasama study found that a large morning surge was not associated with the risk of total stroke events, but rather with a significantly higher risk of cerebral hemorrhage. More prospective studies or meta-analyses are required to better elucidate the prognostic significance of the morning surge in BP.