CLINICAL SIGNIFICANCE OF EXAGGERATED BLOOD PRESSURE



Peter Kokkinos, Ph.D., Veterans Affairs Medical Center, Washington, DC, Georgetown University School of Medicine, George Washington University School, University of South Carolina, USA

During physical work or exercise, systolic blood pressure (SBP) rises progressively with increased workload and plateaus at approximately 180-200 mm Hg, while diastolic BP remains close to or even lower than resting levels. However, in some individuals with prehypertension and established hypertension, SBP rises disproportionately to the workload, achieving levels >200 mm Hg even during sub-maximal exercise. This exaggerated BP response to exercise has been associated with future hypertension, left ventricular hypertrophy (LVH) and cardiovascular disease morbidity and mortality. However, others reported that an exaggerated BP response at peak exercise was associated with lower likelihood of angiographically-determined severity of coronary artery disease and lower mortality rates. This paradoxical finding may be explained by subclinical coronary artery disease (CAD). In the absence of subclinical CAD, myocardial perfusion is preserved even at peak exercise workload, myocardial contractility is sustained and relatively high exercise BP levels are achieved. Conversely, in individuals with subclinical CAD, myocardial ischemia at peak workload is likely to ensue, leading to an attenuated inotropic response, lower exercise BP and termination of exercise. Workloads of 4-5 METs reflect most daily activities. Thus, the BP response at these workloads reflects daytime BP. We examined the clinical significance of BP response at the workloads of 4-5 METs in790 middle-aged, pre-hypertensive individuals. We found a strong association between SBP and LVH. Individuals with SBP -150 mm Hg at the exercise workload of 4-5 METs had a significantly higher LVM index compared to those with systolic BP below this level. The risk of having LVH increased 4-fold for every 10-mm Hg rise in SBP beyond the threshold of 150 mm Hg. Thus, the SBP-LVM association at submaximal workloads suggests that daily exposure to relatively high SBP may provide the impetus for an increase in LVM even at the pre-hypertensive stage.