Propranolol in the Prophylaxis of Migraine ‐ Evaluation by Spectral Analysis of Beat‐to‐Beat Heart Rate Fluctuations

Migraine patients seem to suffer from a continuous autonomic imbalance. Sympathetic instability, expressed by enhanced low frequency fluctuations, which exists during the headache free intervals, was observed in our previous study by spectral analysis of heart rate (HR) fluctuations. Propranolol--a beta adrenoceptor antagonist, is widely used in migraine prophylaxis. In order to specify and quantitate propranolol efficacy in migraine, spectral analysis of heart rate fluctuations was performed on 10 migraine patients before and during the treatment with propranolol. They were compared to 10 healthy control patients and 6 migraine patients who were treated for several months with propranolol and then discontinued the medication. The analysis was carried out on a 24h Holter ECG recording, which was performed for each subject during a headache free interval. Short 256 sec subtraces, taken every 30 min from the 24h ECG signal, were submitted to A/D conversion, R wave detection and computation of heart rate power spectrum. Propranolol achieved a marked effect, when comparing the power spectra of HR fluctuations in treated versus untreated migraine patients. A strong reduction (to normal level) in the low frequency HR fluctuations in the range below 0.1 Hz., was apparent in patients treated with propranolol. Subjects who had received propranolol in the past and discontinued the drug, displayed a carry-over effect of reduced fluctuations even 2-3 months after its discontinuation. It seems that the propranolol efficacy in migraine is associated with the mechanism of stabilizing the fluctuations within the frequency band related to sympathetic activity, hereby moderating the vascular instability in migraine.