ABC | Volume 114, Nº2, February 2020

Original Article Lacerda et al. Mortality in cardioinhibitory carotid sinus hypersensitivity Arq Bras Cardiol. 2020; 114(2):245-253 Figure 3 – Survival curves of patients with (in blue) and without CICSH (in red) CICSH: Cardioinhibitory carotid sinus hypersensitivity. CICSH = absent Strata CICSH = present p = 0.52 Number of patients at risk 0 2 4 6 Time Time 8 10 12 0 2 4 6 8 10 12 Survival probability 1.00 0.75 0.50 0.25 0.00 CICSH=absent CICSH=present Strata 408 360 323 288 256 225 0 52 47 42 38 30 27 0 Table 2 – Mortality at the end of follow-up of patients with and without CICSH With CICSH Without CICSH p value Number of dead patients at the end of follow-up 29/52 (55.8%) 201/408 (49.3%) 0.38 Number of cardiovascular deaths 11/52 (21.2%) 76/408 (18.6%) 0.66 Number of coronary artery disease related deaths 7/52 (13.5%) 32/408 (7.8%) 0.17 Number of cerebrovascular related deaths 2/52 (3.8%) 13/408 (3.2%) 0.80 CICSH: Cardioinhibitory carotid sinus hypersensitivity. reduction of hypotensive therapy, fludrocortisone and alpha‑agonists. 1 Patients with isolated or mixed cardioinhibitory response are usually managed with pacing when syncope is recurrent. 1,2,7 However, many studies used to justify pacing were observational, without a control group, or were small randomized open-label trials with no treatment control arm. 10‑12 Those study results should be regarded with caution. The possibility of spontaneous remission of syncope, the difficulties to document the symptoms used as endpoints and the open-label design of these studies continue to raise doubts about their results. Analogous studies evaluated pacing indications in vasovagal syncope. 13-15 In an early clinical trial, with an open-label design, pacing was able to reduce syncope recurrence. However, in a later double-blind clinical trial, pacing therapy was not advantageous and failed to have any benefit in reducing syncope recurrence. 16 Questions about the efficacy of pacing are even stronger in patients with other types of reflex syncope. Those questions are addressed in 2 recent systematic reviews. 15,16 Interestingly, in one of them an analysis of mortality is made. 16 In this analysis, which includes 3 studies of patients with CICSH and 1 study of patients with vasovagal syncope, pacing therapy did not reducemortality. 16 Only 2 clinical trials evaluated CICSH patients with a double-blind design. 17,18 The first was a double-blind crossover study 17 that randomized 32 elderly patients with at least 3 falls attributed to the presence of CICSH. All patients received dual-chamber pacing. The mean age of the population was 77 years. Patients were followed up for 1 year (6 months with DDD pacing turned on, and 6 months without atrial or ventricular pacing). 17 At the end of follow-up, the reduction in fall burden was similar in both groups. 17 Those results were affected by a high attrition rate. Seven of the 32 patients did not finish the study, 4 of which died during follow-up (12.5% mortality rate). 17 Three of these 4 deaths were sudden and occurred at home, 2 of which occurred in patients without pacing. 17 Autopsy of these patients revealed one death 249