Blood pressure, blood pressure variability and myocardial ischemia : studies in patients with peripheral arterial disease and matched control subjects

Abstract

Background: Patients presenting with peripheral arterial disease (PAD) often have concomitant coronary artery disease (CAD), which is frequently asymptomatic. Ambulatory blood pressure (ABP) monitoring improves risk stratification in hypertensive patients beyond that offered by office BP(OBP) measurements. PAD-patients form a subgroup of high risk hypertensives but there is no controlled study on ABP in these patients. Because standard diagnostic procedures for CAD are less sensitive when patients are limited by symptoms of PAD, other methods like pharmacological stress myocardial perfusion SPECT (MPS) and ambulatory ECG (AECG) have been used for diagnosis of CAD and risk stratification in these patients. Simultaneous registration of AECG and ABP provides the possibility to study relations between episodes of ST-segment depression and changes in blood pressure and heart rate during daily life.

Study I-II: Forty patients (20 men) with a history of intermittent claudication (IC) performed simultaneous 24-hour recordings of AECG and ABP. We found an absence of a white coat effect (OBPaverage day-ABP difference). Thus, OBP was an underestimation of the out of office blood pressure level. Episodes of ST-depression in AECG occurred in a third of the studied population and all episodes occurred during day-time. BP and HR recorded during episodes of ST-segment depression were higher than values recorded in the preceding hour as well as day-mean values. Thirty-eight of these patients underwent 24-hour recordings of ABP prior to randomisation to active treatment with ramipril or matching placebo in the HOPE-study and after one year. Ambulatory BP showed greater falls, especially at night, than OBP during treatment with ramipril given once daily at bedtime. A different day/night variation of BP may be one of several explanations for the beneficial effects of ramipril on cardiovascular outcomes in the HOPE-study.

Study III-V: 98 male patients with PAD and 94 controls matched forage but without PAD or ischemic heart disease (IHD) performed MPS(43 controls), AECG(43 controls) and 24-hour recordings of ABP. Patients with PAD had higher systolic but not diastolic BP than control subjects. In PAD-patients compared to controls, 24h SBP was higher than what could be expected from OBP. Night SBP was higher only in PAD-patients with antihypertensive treatment. The prevalence of episodes of STsegment depression during AECG-monitoring was 15% in PAD-patients compared to 5 % in control subjects (p=0.07). The majority of these patients had no inducible ischemia on a dipyridamole stress MPS. In the patients with signs of reversible ischemia on SPECT only a small subgroup had evidence of ischemia on AECG. Episodes of ST-depression were related to an increase in ambulatory BP and HR and with diary reported physical activity. NT-pro-BNP-levels were markedly increased in PADpatients compared to controls and further increased in PAD-patients with ECG-LVH and SPECT perfusion defects. In multivariate analysis average night pulse pressure, creatinine-clearance, ECGLVH, and history of IHD remained independently related to NT-pro-BNP-levels in PAD-patients.

Conclusions: The severity of hypertension may be underestimated in PAD-patients, when based on OBP only, and especially so in patients on antihypertensive treatment. Different methods for detection of myocardial ischemia in PAD-patients are incongruent. Measurement of NT-pro-BNP could be implicated in PAD-patients for further risk stratification.