Evaluation of sinus and atrioventricular nodes function in patients with vasovagal syncope

Are women really more affected by vasovagal syncope than men?

It is commonly reported that vasovagal syncope (VVS) is more frequent in women. Presently, this issue has never been investigated. The purpose of this review was to evaluate, through an extensive review of the literature, whether women are really more affected by VVS than men. The gender distribution was investigated in individuals with classical and nonclassical VVS. The database PubMed was searched using the terms 'syncope', 'vasovagal syncope', 'neurally mediated syncope' and 'tilt testing'. Twelve studies dealing with classical and 75 with nonclassical VVS were eligible. In the individuals with classical (N = 1861) and nonclassical VVS (N = 9696), a trend towards a greater percentage of women emerged (P = 0.14 and 0.07, respectively). In the total population with VVS (N = 11 557), the percentage of women was significantly higher than that of men (58 versus 42%, P = 0.03). Most of the individuals were young or middle-aged. In 84% of the studies, the percentage of women was greater than that of men. A separate analysis was carried out in older VVS patients (≥60 years) and only two studies were eligible to be evaluated. Considering that almost all the studies were carried out in the western nations, where the number of men and women is almost superimposable until the age of 65 years and a bias by gender has never been reported in the management of VVS, these data strongly suggest that young and middle-aged women are more affected by VVS than their male counterparts. At present, data are too scant to draw a definitive conclusion in older VVS patients.

Atrial electromechanical conduction delay in patients with neurocardiogenic syncope

AIM

We aimed to investigate the presence of atrial electromechanical conduction delay in patients with neurocardiogenic syncope, which was diagnosed with head-up tilt table test (HUTT).

MATERIALS AND METHODS

A total of 29 patients (mean age: 30.6 ± 15.9 years) with vasovagal syncope, as diagnosed by HUTT, and 23 healthy control subjects (mean age: 34.7 ± 16.3 years) with a negative HUTT were enrolled to the study. Atrial electromechanical conduction delay was defined as the time elapsed from the beginning of the P wave in the electrogardiogram to the beginning of the Am wave in tissue Doppler.

RESULTS

There was no statistically significant difference between the groups in terms of interatrial conduction delay, whereas the difference was significant with regard to the right intraatrial electromechanical conduction delay (P < 0.01) and the left intraatrial electromechanical conduction delay (P < 0.0001). There was a negative correlation between the left intraatrial electromechanical conduction delay and the right intraatrial electromechanical conduction delay (r = -0.486, P = 0.001), whereas a positive correlation was present with the interatrial electromechanical conduction delay (r = 0.507, P = 0.001).

CONCLUSION

In this study, the tissue Doppler method revealed that there is left and right intraatrial electromechanical conduction delay in patients with vasovagal syncope. The impact and role of atrial conduction delay as a pathophysiological determinant should be confirmed in further studies.

Prediction of sinus node dysfunction in patients with long-standing persistent atrial fibrillation using the atrial fibrillatory cycle length

BACKGROUND

Sinus node dysfunction (SND) occasionally coexists with long-standing atrial fibrillation (AF) but is unidentifiable during AF. We aimed to identify the predictors of underlying SND when deciding the indications for long-standing persistent AF ablation.

METHODS

We included 105 patients undergoing ablation of long-standing persistent AF to assess the frequency of a permanent pacemaker implantation (PMI) for SND that manifested after sinus conversion and to determine the relationship between the corrected sinus node recovery time (CSNRT) and other clinical parameters obtained before the ablation including the atrial fibrillatory cycle length (AFCL).

RESULTS

We identified 7 patients (7%) requiring a PMI for SND after AF termination. The patients with a PMI were nearly all females (6/7) and had a significantly longer CSNRT (1197 ± 647 vs 612 ± 349 milliseconds; P = .0046) and more prolonged AFCL (179 ± 19 vs 153 ± 22 milliseconds; P = .0028) than those without. The age (r = 0.26; P = .011), female sex (r = 0.25; P = .012), hypertension (r = 0.22; P = .038), and AFCL (r = 0.4; P < .0001) were significantly correlated with the CSNRT. A stepwise multivariate linear regression analysis including these parameters revealed that the AFCL was the only independent determinant of the CSNRT (β = 0.38; P = .0012). A receiver operating characteristic curve identified an AFCL of more than 162 milliseconds as the optimal cutoff value for predicting SND requiring a PMI (area under the curve, 0.84; sensitivity, 86%; specificity, 74%; P = .0066).

CONCLUSIONS

A prolonged AFCL was significantly associated with SND. Thus, assessing the AFCL in the patients with long-standing persistent AF may be helpful for the risk stratification of underlying SND.

Physiological phenomenology of neurally-mediated syncope with management implications

BACKGROUND

Due to lack of efficacy in recent trials, current guidelines for the treatment of neurally-mediated (vasovagal) syncope do not promote cardiac pacemaker implantation. However, the finding of asystole during head-up tilt -induced (pre)syncope may lead to excessive cardioinhibitory syncope diagnosis and treatment with cardiac pacemakers as blood pressure is often discontinuously measured. Furthermore, physicians may be more inclined to implant cardiac pacemakers in older patients. We hypothesized that true cardioinhibitory syncope in which the decrease in heart rate precedes the fall in blood pressure is a very rare finding which might explain the lack of efficacy of pacemakers in neurally-mediated syncope.

METHODS

We studied 173 consecutive patients referred for unexplained syncope (114 women, 59 men, 42 ± 1 years, 17 ± 2 syncopal episodes). All had experienced (pre)syncope during head-up tilt testing followed by additional lower body negative suction. We classified hemodynamic responses according to the modified Vasovagal Syncope International Study (VASIS) classification as mixed response (VASIS I), cardioinhibitory without (VASIS IIa) or with asystole (VASIS IIb), and vasodepressor (VASIS III). Then, we defined the exact temporal relationship between hypotension and bradycardia to identify patients with true cardioinhibitory syncope.

RESULTS

Of the (pre)syncopal events during tilt testing, 63% were classified as VASIS I, 6% as VASIS IIb, 2% as VASIS IIa, and 29% as VASIS III. Cardioinhibitory responses (VASIS class II) progressively decreased from the youngest to the oldest age quartile. With more detailed temporal analysis, blood pressure reduction preceded the heart-rate decrease in all but six individuals (97%) overall and in 10 out of 11 patients with asystole (VASIS IIb).

CONCLUSIONS

Hypotension precedes bradycardia onset during head-up tilt-induced (pre)syncope in the vast majority of patients, even in those classified as cardioinhibitory syncope according to the modified VASIS classification. Furthermore, cardioinhibitory syncope becomes less frequent with increasing age.