How to Best Assess Blood Pressure?

Abstract

See related article, pp 1087-1093 I t is half a century since high blood pressure (BP) measured in the doctor's office has been proved to be a strong predictor of cardiovascular morbidity and mortality. However , it soon became clear that multiple factors can significantly affect the BP measurement result (Table 1) and may thereby have considerable impact on its prognostic ability. Despite the intensive research with almost 120 000 PubMed papers on issues related to BP monitoring, the question "how to best assess BP" is still a matter of hot debate. Notwithstanding these difficulties, research in the field of BP monitoring has considerably refined the BP measurement procedure, by systematically addressing all factors listed in Table 1. Such improvement has included a better standardization of methods as well as the development of multiple approaches to BP quantification, aiming to more precise risk prediction. This was achieved not only by a more accurate estimation of mean BP, but also by the evaluation of different patterns of BP variation over time. Although, irrespective of the measurement methodology (Table 1), any BP value is by itself a powerful index of risk, several aspects of BP dynamics assessed by considering patterns of BP change over time have been proved to increase the prognostic ability of BP, over and above the information provided by conventional office measurements. Practicing physicians, as well as patients themselves (par-ticularly those self-monitoring their BP at home), are frequently concerned by the possibility that BP fluctuations occurring in daily life, which often rise well above the average BP level, might cause additional hemodynamic stress on the heart and vasculature, increasing thereby the risk of organ damage. Indeed, the frequent occurrence of BP fluctuations , sometimes of non-negligible magnitude, is evident with all the routinely used BP-monitoring methods (office, home, and ambulatory). However, despite the accumulating evidence on the clinical relevance of BP fluctuations over and above that of average BP, 1-6 this issue largely remains an interesting hypothesis only, and in clinical practice BP values with large deviation away from the average are usually regarded as "random" and "noise" and are ignored. In this issue of the journal, Matsui et al 7 provide evidence that in untreated hypertensives the maximum systolic BP value of 14-day home monitoring is more closely related with cardiac and vascular damage than average home BP. Moreover , maximum home BP showed independent predictive ability for target organ damage, beyond that of average home BP. In a recent retrospective analysis by Rothwell et al, 4 maximum BP assessed by office measurements was also a strong predictor of stroke independently of the mean BP. In the same line, a study in acute ischemic stroke showed that the maximum BP assessed during the first 3 days in hospital was closely associated with the risk of developing hemor-rhagic transformation independently of the mean BP. 5 Thus, occurrence of BP peaks, wherever assessed (office, home, or hospital), appears to provide independent prognostic information beyond that of average BP. These data are supported by reports on the association between the morning surge in BP