The relationship between carotid sinus hypersensitivity, orthostatic hypotension, and vasovagal syncope: a case-control study.

AIMS: Previous uncontrolled studies reported an overlap between carotid sinus hypersensitivity (CSH), vasovagal syncope (VVS), and orthostatic hypotension (OH). We conducted a case-control study evaluating this relationship in a large patient cohort.

METHODS AND RESULTS: The electronically stored continuous electrocardiograph and blood pressure (BP) measurements for active stand and head-up tilt-table (HUT) tests of 302 consecutive patients investigated with carotid sinus massage (CSM) were analysed. Carotid sinus hypersensitivity was defined as >or=3 s asystole and/or systolic BP (SBP) drop of >or=50 mmHg during CSM. Orthostatic hypotension was defined as BP reductions of >or=20 mmHg systolic or of >or=10 mmHg diastolic, whereas VVS was diagnosed with a positive HUT test. There was no significant difference in the number of subjects with OH (57 vs. 55%; P = 0.778) or HUT-positive VVS (45 vs. 47%; P = 0.828) between cases with CSH and controls without CSH. Carotid sinus hypersensitivity subjects had significantly larger SBP reduction (P = 0.039) and longer time to nadir (P = 0.007) during active stand, and trends to vasodepressor (P = 0.071) and dysautonomic responses to HUT (P = 0.151).

CONCLUSION: Carotid sinus hypersensitivity, OH, and VVS are common conditions affecting patients with syncope and falls which are likely to co-exist in such individuals. The differences in haemodynamic response patterns to active stand and HUT in CSH subjects could be the result of an age-associated delay in sympathetic responses.