Autonomic antecedents to variant angina exacerbation after beta-blockade withdrawal

We describe a patient with nonsignificant coronary artery disease who experienced variant angina after beta -blockade withdrawal. Standard therapy with nifedipine and nitrates aimed at suppressing symptoms and typical transient ST-segment elevations was superseded by the reinstitution of metoprolol. The autonomic alternations before and after readministration of metoprolol were analyzed by time and spectral indices of heart rate variability (HRV). Metoprolol reduced the HRV and reversed the low-frequency/high-frequency power ratio toward a more physiological autonomic balance. We conclude that the reinstitution of beta -blocker acted protectively by preventing surges of sympathetic activity on an underlying basis of parasympathetic predominance.