Arterial stiffness evaluated by measurement of the QKD interval is an independent predictor of cardiovascular events.

BACKGROUND: The QKD interval is the time between the QRS wave on the electrocardiogram (ECG) and the detection of the last Korotkoff sound during BP measurement. Measurement of the QKD interval during ambulatory blood pressure (BP) monitoring provides an automatic evaluation of arterial stiffness. The objective of this longitudinal study was to examine the relationship between arterial stiffness assessed by this method and the occurrence of cardiovascular complications in a cohort of initially untreated hypertensive patients. METHODS: The initially untreated hypertensive patients were included in the cohort of hypertensives recruited to our center between January 1992 and December 1999. All benefited from ambulatory measurement of the QKD interval and BP over 24 h. Most of these patients were given antihypertensive treatment and were followed up by their family physicians, who were unaware of the QKD results. Their outcome was evaluated in 2003 by inquiring of the patients themselves or of their family physicians. RESULTS: The initial population comprised 412 patients. At the end point, 33 had been lost to follow-up. We recorded 49 cardiovascular events in this population with an average follow up of 65 +/- 36 months. In a Cox model, the arterial stiffness assessed by the QKD(100-60) as a percentage of the height-predicted normal value was significantly associated with the occurrence of cardiovascular complications, independent of age and mean 24-h BP. CONCLUSIONS: This study using ambulatory measurement of the QKD interval showed that an increase in arterial stiffness was a marker of cardiovascular risk. We show for the first time that its value persists after taking account of the mean systolic pressure over 24 h.

Blood pressure surge on rising.

OBJECTIVES: Since cardiovascular complications tend to occur more often in the morning, it is tempting to link this to the surge in blood pressure (BP) on rising. Our objective was to measure BP and heart rate (HR) on rising and compare values with those recorded immediately beforehand and seek variables related to marked changes in the two parameters in a cohort of initially untreated hypertensives. METHODS: The 24-h ambulatory BP measurement along with an accurate measurement of the BP on rising (either manually or automatically from the device coupled with a position sensor) was obtained in untreated hypertensives. Left ventricular mass was measured with echocardiography at baseline. Patients were then treated and followed by their general physician and news was obtained at regular intervals. RESULTS: A total of 507 patients with adequate recordings were included. Rising led to a mean increase of 14 mmHg in systolic blood pressure (SBP) and a 13 beats per minute (bpm) increase in HR. This elevation in BP on rising in the morning differed from the alteration in BP on normal changes in position. It was associated with left ventricular hypertrophy at baseline and an increased risk of future cardiovascular complications. CONCLUSIONS: Our study confirms the surge in BP on rising in the morning. This elevation in BP is accompanied by an acceleration in cardiac rhythm with no significant correlation between the two parameters. The increase in BP on rising was linked with the overall variability in BP, but was independent of the mean BP over 24 h. It was associated with an increased risk of cardiovascular complications independently of age and average 24-h SBP.