[Hypersensitivity and carotid sinus syndrome in patients with chronic atrial fibrillation].

BACKGROUND

Carotid sinus hypersensitivity (CSH) has always been described in patients in sinus rhythm; we did not find reports of CSH in patients with chronic atrial fibrillation (AF). After the observation of bilateral CSH in a patient with chronic AF admitted to our Division for syncope, we began to systematically study patients with chronic AF and neurological disturbances to evaluate carotid sinus stimulation effects upon cardiac activity and arterial blood pressure in these subjects.

METHODS

We studied 28 subjects with chronic AF (mean age 73.3 yrs.; range 60-89): 16 patients had dizziness, fainting or syncope, and formed the study group (A); 12 asymptomatic patients were considered the control group (B). After a careful clinical and instrumental evaluation, all the patients underwent a 24 hour ambulatory (Holter) ECG analysis and right and left carotid sinus massage (CSM). If the latter manoeuvre induced asystolia longer than 3 seconds, CSM was repeated during ventricular pacing to evaluate the vasal component of the carotid sinus reflex.

RESULTS

In group A, 24-hour Holter monitoring showed a greater incidence (81.2%) of ventricular standstill (mean duration 2.67 seconds) in comparison to the control group. In group A we found CSH in 75% of the cases, more frequently right CSH (7 subjects with right, 1 with left and 4 with bilateral CSH) with prolonged ventricular asystolia (mean duration 5.3 +/- 1.9 sec. with right CSM; 7.8 +/- 1.4 sec. with left CSM); during CSM, we reproduced spontaneous symptomatology in 9 patients. In 12 patients in group A, diagnosis of carotid sinus syndrome was established; the cardioinhibitory forms were clearly prevalent (91.7%); only one patient presented a cardioinhibitory-vasodepressor form with a predominant vasodepressor component.

CONCLUSIONS

The authors believe that CSH is frequent in patients with chronic AF; the vagal hyperactivity due to CSH can induce prolonged ventricular asystole that may be responsible for neurological disturbances such as dizziness, fainting or syncope, as observed in patients in sinus rhythm with carotid sinus syndrome. Abnormal sensitivity of the carotid sinus could thus be one of the causes of increased morbidity and mortality in patients with chronic AF. The majority of these patients may be expected to benefit from permanent pacemaker therapy.