Autonomic modulation and QT interval dispersion in hypertensive subjects with anxiety

Anxiety is associated with an increased risk of sudden death. QT dispersion is a marker of cardiac repolarization instability and is seen in conditions of high risk of sudden death. The purpose of this study was to evaluate autonomic nervous system control and QT dispersion in hypertensive subjects with anxiety symptoms. In a recent preliminary study, we observed that hypertensive individuals reporting high scores on a self-assessment anxiety scale had more marked left ventricular hypertrophy. In 105 hypertensive subjects divided into 3 groups according to severity of anxiety, we evaluated autonomic control by short-term power spectral analysis of RR and arterial pressure variability at rest (baseline) and during sympathetic stress (tilt test), left ventricular mass index, and heart rate-corrected QT (QTc) dispersion. At baseline, hypertensive subjects with higher anxiety symptom scores had significantly lower high-frequency RR values expressed in absolute terms (P<0.05) and in normalized units (P<0.05) than their counterparts without anxiety symptoms. Hypertensive subjects with anxiety also had a higher mean left ventricular mass index (P<0.001) and greater QTc dispersion (P<0.001). Both indexes and high frequency (P<0.05) correlated with severity of anxiety. These findings suggest that anxiety is associated with autonomic imbalance. This condition could favor an increase in left ventricular mass. Myocardial hypertrophy alone or combined with neuroautonomic imbalance may lead to QT dispersion.