Excessive supraventricular activity and risk of atrial fibrillation in patients with cryptogenic ischaemic stroke.

INTRODUCTION: Atrial fibrillation (AF) is one of the leading causes of ischaemic stroke. However, screening for AF is often time-consuming in clinical practice. Therefore, the determination of an appropriate marker to detect the presence of AF would improve the diagnostic process. OBJECTIVE: The aim of the current study was to evaluate the efficacy of prolonged and early inpatient event Holter monitoring in the detection of AF in patients with ESUS-related cryptogenic ischaemic stroke (CIS), and to determine the possible relationship between excessive supraventricular activity and AF detection. MATERIAL AND METHODS: All consecutive patients with documented cerebral or cerebellar infarction were included. The diagnostic work-up included brain neuroimaging (CT/MRI), ultrasound of the carotid and vertebral arteries, admission ECG followed by 24 hours of Holter monitoring, and transthoracic echocardiography. The 24-hour Holter ECG was analysed, and supraventricular ectopic activity (supraventricular extrasystoles, runs and pairs of supraventricular extrasystoles) was recorded in all patients. If these examinations did not reveal the cause of ischaemic stroke, the patients underwent subsequent prlonged 14-day event Holter recorder monitoring. RESULTS: We included 48 patients (mean age 69.9 ± 8.5 years, 60.4% men) who had been diagnosed with CIS. Of these 48 patients, atrial fibrillation was detected in seven (14.6%) during the prolonged 14-day Holter event monitoring. Patients with newly diagnosed atrial fibrillation had a higher burden of supraventricular ectopic activity. The number of supraventricular extrasystoles (SVES) per hour, as well as the number of SV pairs and SV runs, was significantly higher in patients with new onset AF (p < 0.022; p < 0.043; p < 0.022). CONCLUSIONS: In our study, we confirmed that prolonged ECG event Holter monitoring in patients with CIS-ESUS subtype led to a higher rate of AF detection. Likewise, frequent supraventricular ectopic activity predicted the development of AF.

Etiology of syncope in patients with preexisting atrioventricular conduction disorders.

BACKGROUND: The discussion about the feasibility of empiric pacemaker implantation in patients with preexisting atrioventricular (AV) conduction disorders continues. The aim of the study was to determine the etiology of syncope and the need for pacemaker insertion in patients with AV conduction impairment using implantable loop recorder (ILR). METHODS: ILR was implanted after negative diagnostic workup in 37 patients with syncope (24 men, 13 women, age 72 ± 10 years) and preexisting impairment of AV conduction. First-degree AV block (AVB I) was present in 26 patients, and bundle branch block (BBB) in 17 patients. RESULTS: ILR-based diagnosis was made in 28 patients (75%)-sinus arrest in 13 patients, complete AVB in 10 patients, and vasodepressor syncope in five patients. In patients with preexisting BBB, sinus arrest occurred during ILR monitoring significantly more frequently than in patients without BBB (53% vs 20%, P = .03). Complete AVB was significantly less common in patients with preexisting BBB than in patients without BBB (12% vs 40%, P = .04). On multivariate regression analysis, the only independent predictor of AVB occurrence during ILR monitoring was preexisting AVB I (P = .03). The only independent predictor of sinus arrest during ILR monitoring was preexisting BBB (P = .03). CONCLUSIONS: In patients with preexisting AV conduction disorders, prevailing syncopal mechanism during ILR monitoring was asystole. However, sinus arrest occurred more often than complete AVB and was predicted by preexisting BBB. Preexisting AVB was a predictor of complete AVB during ILR monitoring.

Improvement in low upright baroreflex sensitivity is associated with positive clinical effect of orthostatic training.

AIM: To assess the clinical efficacy of orthostatic training (OT) and its effect on the autonomic activity. METHODS: OT was performed in 38 patients (13 males, age 36.4 ± 15.2 years). Baroreflex sensitivity (BRS), heart rate variability, and quality of life (SF 36) were assessed before and after 6 months of OT. Patients with no recurrence of syncope and reduction of the presyncope number to one-third or less were classified as responders. RESULTS: Compliance to OT was low. Only 55% (38 from 69 patients) completed the training programme; 28 patients were responders (74%) and 10 patients were nonresponders. Before OT, BRS in upright position was lower in responders than in nonresponders (sitting: 8.05 ± 3.94 ms/mm Hg vs 12.51 ± 5.3 ms/mm Hg, P = 0.04, standing: 5.08 ± 2.34 ms/mm Hg vs 7.54 ± 2.16 ms/mm Hg, P = 0.02). After OT, BRS increased in responders (sitting: 8.05 ± 3.94 ms/mm Hg to 9.31 ± 4.49 ms/mm Hg, P = 0.05; standing: 5.08 ± 2.34 ms/mm Hg to 5.96 ± 2.38 ms/mm Hg, P = 0.03). No differences in supine BRS were observed. In responders, low frequency (LF) and high frequency (HF) power in sitting and standing positions significantly increased after OT (P < 0.05). In nonresponders, there was no significant rise in BRS, LF, and HF after OT. A significant increase in quality of life was noted in responders, but not in nonresponders. CONCLUSIONS: OT reduced symptoms in 74% patients who trained regularly. However, the compliance to training was low. Possible mechanism of OT is reconditioning effect on baroreceptor reactivity in upright position.

Clinical characteristics associated with bradycardia and asystole in patients with syncope undergoing long-term electrocardiographic monitoring with implantable loop recorder.

BACKGROUND: The aim of this retrospective single center cohort study was to assess the occurrence of bradycardia during implantable loop recorder (ILR) monitoring in patients with unexplained syncope and negative conventional testing and to identify clinical predictors of bradycardia and pacemaker implantation. METHODS: An ILR was implanted in 112 patients (31 men, 81 women, mean age 64 ±13 years) with syncope which was not explained after conventional diagnostic work-up. Clinical variables were compared between patients with and without pacemaker implantation. RESULTS: A diagnosis was made in 67 patients (60%), including non-arrhythmic (vasodepressor) syncope (27 patients), sinus bradycardia or asystole (23 patients), atrioventricular (AV) block (14 patients) and bradycardic atrial fibrillation (3 patients). The mean time to diagnosis was 233 ± 282 days. A pacemaker was implanted in 40 patients (36%). Male gender, age above 65 years, hypertension, presence of structural heart disease, absence of prodromal symptoms, trauma secondary to syncope, asymptomatic sinus bradycardia and first-degree AV block were clinical predictors of pacemaker implantation in univariate analysis. Of the independent predictive factors three remained significant in multivariate analysis: absence of prodromal symptoms before the loss of consciousness (odds ratio OR 3.38, p = 0.01, 95% confidence interval CI 1.24-9.20), male gender (OR 3.22, p = 0.01, 95% CI 1.26-8.20) and age >65 years (OR 2.94, p = 0.02, 95% CI 1.14-8.33). CONCLUSIONS: In patients undergoing ILR implantation bradycardia is a frequent finding despite the negative conventional diagnostic testing. Absence of prodromal symptoms, male gender and age >65 years are risk factors for bradycardia and pacemaker implantation.

Gene Polymorphism of the Adenosine A2a Receptor in Patients with Vasovagal Syncope.

BACKGROUND: Adenosine may play a role in the pathogenesis of vasovagal syncope (VVS). The aim of the study was to evaluate the adenosine A(2A) receptor gene 1083 T > C polymorphism in patients with syncope and its possible association with results of head-up tilt test (HUT). METHODS: Three hundred and forty-seven consecutive patients (mean age 47.3 ± 18.5 years, 132 men, 215 women) with one or more syncopal episodes underwent HUT as part of standardized diagnostic evaluation. HUT was positive in 207 patients (75 males, mean age 44.7 ± 18.6 years) and negative in 140 patients (58 males, mean age 48.17 ± 18.8 years). One thousand and eighty-three T > C single nucleotide polymorphism in the adenosine A(2A) receptor gene (rs5751876) was evaluated in 347 patients with syncope and in 85 subjects without history of syncope (54 men, mean age 41.7 ± 16.3). RESULTS: Adenosine A(2A) receptor 1083 T > C polymorphism was not associated with the positivity of HUT. Blood pressure and heart rate response to tilting was similar in all genotypes. Low frequency (LF) power was significantly lower in CC genotype compared to CT genotype in early phase of tilt (log LF 2.69 ± 0.61 vs 3.20 ± 0.60; P = 0.01) and at the time of syncope (log LF 2.60 ± 0.63 vs 2.77 ± 0.48; P = 0.04). CONCLUSIONS: Adenosine A(2A) receptor 1083 T > C polymorphism is not associated with the positivity of HUT and its proposed role in predisposition to VVS was not confirmed. CC genotype may be associated with lower sympathetic activity during HUT.

Regional myocardial contractile reserve assessed by strain echocardiography and the response to cardiac resynchronization therapy.

BACKGROUND: Overall response rate to cardiac resynchronization therapy (CRT) is still not optimal. The aim of the study was to evaluate the influence of the regional myocardial contractile reserve during dobutamine infusion in the area of left ventricular (LV) electrode on the response rate and reverse remodeling LV in patients receiving CRT. METHODS: Biventricular pacemaker was implanted in 41 consecutive patients (33 men, mean age 62 ± 10 years) with LV ejection fraction (LVEF) ≤ 35%, New York Heart Association class III and QRS duration ≥ 120 ms. Myocardial contractile reserve was assessed by LV strain during dobutamine infusion (20 µg/kg/min) using speckle tracking echocardiography. Patients were classified as responders if an increase in LVEF ≥ 5% or decrease in end-systolic volume ≥ 15% was observed after 6 months of CRT. RESULTS: Twenty-four patients were responders and 17 were non-responders. During dobutamine infusion at a rate of 20 µg/kg/min, responders showed significant increase in regional deformation (Δ strain) when compared to non-responders (2.14 ± 2.9 vs. - 0.94 ± 1.74, p = 0.042). Patients with increased deformation in the LV lead area during dobutamine stimulation were more likely to be responders to CRT compared to patients without increased deformation in this area (81% vs. 20%, p = 0.0002). They exhibited significant increase in LVEF (8.8% ± 10.3% vs. 0.3% ± 6.4%, p = 0.01). LV electrode localization in viable myocardium was a good predictor of response to CRT (AUC 0.852, p < 0.0001). CONCLUSIONS: Regional contractile reserve assessed by strain rate echocardiography during dobutamine infusion predicts the response to CRT.