Increased myocardial repolarization lability and reduced cardiac baroreflex sensitivity in individuals with high-normal blood pressure.

BACKGROUND

Recent guidelines for the management of arterial hypertension have proposed that, to prevent cardiovascular disease, lifestyle modifications are required even in the case of high-normal blood pressure (HNBP).

OBJECTIVE

To assess myocardial repolarization and spontaneous cardiac baroreflex sensitivity (BRS) in newly diagnosed and never-treated individuals.

DESIGN AND PARTICIPANTS

We studied healthy individuals with HNBP according to the 2003 European Society of Hypertension-ESC guidelines and, for comparison, patients with renovascular hypertension (RVH) and healthy individuals with normal blood pressure (NBP).

MAIN OUTCOME MEASURES

Electrocardiogram and beat-to-beat blood pressure were recorded and spontaneous cardiac baroreflex sensitivity and the temporal QT interval variability index (QTVI) were calculated.

RESULTS

Individuals with HNBP had increased QTVI values compared with those with NBP (-1.23 +/- 0.37 compared with -1.52 +/- 0.26; P < 0.05), whereas patients with RVH had additionally increased QTVI values that were greater than those in healthy individuals with NBP or HNBP (-0.81 +/- 0.75; P < 0.05 compared with both groups). BRS was reduced in both groups of individuals with increased blood pressures compared with NBP (8.2 +/- 4.1 ms/mmHg for individuals with HNBP, 6.1 +/- 4.3 ms/mmHg for patients with RVH and 10.8 +/- 3.5 ms/mmHg for NBP; P < 0.05 for both).

CONCLUSION

In otherwise healthy individuals, even a moderate blood pressure increase is associated with increased myocardial repolarization lability and reduced baroreflex sensitivity (BRS). Patients with RVH have an additionally increased QTVI, with values similar to those reported in congestive heart failure. Future studies are needed to establish the value of QTVI and BRS measurements among individuals with HNBP in predicting the risk of progression to hypertension and end-organ damage.