Adrenergic beta blockade and ECG changes in the systolic click murmur syndrome.

In an attempt to elucidate the ECG changes associated with the SCMS, we have applied the propranolol test in 35 of our patients suffering from this syndrome. To the best of our knowledge this is the first such report in the English literature. Twenty-eight patients showed improvement and this points against an ischemic etiology. The test may be applied to differentiate ischemic ST-T changes from those associated with the SCMS. We have suggested the possibility of sympathetic overactivity and autonomic imbalance as the basis for the ECG and other features related to the SCMS. We have noted the striking similarities in the symptomatology and ECG changes associated with the SCMS and those of neurocirculatory asthenia. The implication of this was discussed.