УДК: 616.12-008.3

1,2Badykova E.A., 2Plechev V.V., 1,2Badykov M.R.,

1Sagitov I.S., 3Lakman I.A., 2,3Zagidullin N.S. 1Republic Bashkortostan Cardiological Сenter, 96 Stepan Kuvykin Str., Ufa, Russia, 450106

2Bashkir State Medical University, 3 Lenin Str., Ufa, Russia, 450008

3Ufa State Aviation Technical University, 12 Karl-Marx Str., Ufa, Russia, 450077

Analysis of patients register with sick sinus syndrome and implanted pacemaker in Republic of Bashkortostan

Abstract. Sick sinus syndrome (SSS) is a relatively sel- dom disease characterized by symptoms of tissue hypoperfusion and manifestations on the electrocardiogram, whose frequency increases with age, causes sudden mortality and leads to the installation of pacemakers.

Key words: SSS, cardiovascular events, pacemaker, morbidity.

Contact person:

Naufal Zagidullin

Professor of Department of Internal Diseases of Bashkir state Medical University; 3 Lenin Str., 450008, Ufa, Russian Federation, tel. +7(347)2465397, e-mail:  Этот адрес электронной почты защищен от спам-ботов. У вас должен быть включен JavaScript для просмотра.

Sick sinus syndrome (SSS) is a pathological condition in which the generation of the action potential by cells of the sinoatrial node (SAN), which does not correspond to the physiological requirements of the organism and is characterized by its dysfunction [1,5]. Although the frequency of SSS development increases exponentially with age, it can manifest in almost any person, including newborns. The average age for the development of the syndrome is about 68 years [6], and is usually equally distributed among the men/women. In SSS the formation of an electric impulse in the SAN and / or conduction in the atria is impaired, which leads to a pathological decrease in the heart rate (HR) or rhythm pauses. The frequency of SSS among the patients with coronary heart disease (CHD) is very high [7].

Arterial hypertension and cardiomyopathy are a small but important group of diseases that predispose to the development of SSS. Several mutations of the ion channel genes have been identified, which can lead to a hereditary transmission of the syndrome [8, 9, 10, 11]. In the Republic of Bashkortostan, the Department for the surgical treatment of complex cardiac arrhythmias and pacemaking of the Republican Cardiology Center is practically the only one in which the pacemakers are implanted and in which its function is monitored and regulated. As part of the creation of the register of patients with SSS, the patient characteristics were analyzed.

 The aim of the study was to create a register of patients with SSS with implanted pacemakers and to investigate their clinical and demographic features in real clinical practice.

 Methods

The study design is non-randomized, prospective without a control group. The diagnosis SSS was made in the presence of symptoms of ischemia and hypoperfusion of organs and, above all, the brain, with bra- dycardia and/or tachycardia [12]. In this case, both complaints and clinical symptoms, as well as corresponding changes in electrocardiogram, should be present. Severe bradycardia, including sinoatrial (SA) pauses of 3 or more seconds, were diagnostically significant only with the correspond- ing clinical symptoms.

SSS was classified in accordance with modern guidelines: sinus bradycardia, SA blockade of II degree, of III degree, SA failure and "tachy-brady" syndrome. All patients underwent pacemaker implantation in the period 2012-2015. Types of implantable pacemaker were: single-chamber atrial, dual-chamber atrioventricular and single-ventricular (Table 1).

 Implantation was performed in the department of surgical treatment of complex cardiac arrhythmias and pacing and further monitoring was performed in the ambulant unit of the institution.

 Statistics. Data are presented as mean and mean error (M±m). Non- parametric Mann-Whitney test with value of p<0.05 considered to be significant.

Results

 Demographic and clinical characteristics of patients are presented in Table 2 and Figure 1. All patients were diagnosed with SSS and the pace- maker was implanted. A total of 610 patients with an average age of 69.2 ± 0.48 years were examined. Almost all patients (97.2%) were diagnosed with CHD, and the majority had a concomitant diagnosis of arterial hypertension (81.6%) and in a small part of diabetes mellitus (DM) (8.7%) and myocardial infarction (MI) in the anamnesis (10.3%).

Among most patients the left ventricular ejection fraction (LVEF) determined by the Treyholtz method during echocardiography was preserved (61.7± 0.3%), and HR was mainly less than 50 bpm (42.4 ± 0.4%), which means that bradycardia was present in the most of patients.

During the period from 2012 to 2015 all patients underwent pacemaker installation. The installed types of pacemaker are presented in Table 3 and Fig.1. The most frequently installed was two-chamber pacemaker with frequency adaptation (n = 258, 42.2%), less often - single-ventricular ventricular (167, 27.4%) and most rare- ly - single-chamber with adaptation - 52 (52, 8.5 %).

All 6 groups of patients with SSS, groups according to type of pacemaker (AAI, DDD, DDDR, VVI, VVIR, AAIR), were tested on the differences between the features: age, gender, arterial hypertension, CHD, MI in the past, LVEF, HR before pacemaker installation. Paired comparison using nonparametric Mann-Whitney test of each factor showed ”0” hypothesis and absence of differences between the groups (p>0.05).

In the majority of cases (n=507, 83.1%), the established pacemakers paced the rhythm, in 16.1% (n=98) the device functioned in the "demand" mode and in 5 (0.82%) was atrial fibrillation.

Discussion

Sick sinus syndrome is a pathological condition in which the generation of action potential in SAN cells that does not correspond to the physiological requirements of the body. In such patients, the risk of sudden death is high [2], and the reason for pacemaker implantation in more than 50% is SSS [3]. Therefore, the study of the demographic and clinical features of patients with SSS disease is very relevant.

 In 610 patients SSS were diagnosed and the pacemakers were implanted. This part of the research project was carried out as a part of register of patients with the syndrome followed for monitoring for unfavorable cardiovascular events (myocardial infarction, stroke,death). In addition, within the framework of the project, genetic polymorphism genes of connective tissue and ion channels polymorphism was investigated.

Like in rest of the world, in our study SSS proved to be quite an "adult" disease (69.2 ± 0.48 years) [5,6]. If, according to the literature, the incidence of syndrome was the same for men and women [5,12], but in our study, the distribution between the genders was 44.6% versus 55.4%, respectively. SSS, as in other studies, was fast always associated with the presence of CHD (97.2%), but the ejection fraction in most patients was within the normal range. A small proportion of patients, less than 10%, had such risk factors as DM and MI in history. In addition, in patients, arterial hypertension was less common than CHD.

Most of pacemakers established in SSS were in sinus bradycardia variant (63.4%), which also corresponded to the HR (42.4 ± 0.4 bpm). Less often 2nd degree SA blockade (13.2%), 3d degree (6.8%) and SA node failure (12.6%) and most rarely -tachybrady syndrome (3.0%) were diagnosed. Modern recommendations require the installation dualchamber pacemakers in SA blockade and single-chamber atrial with bradycardia [4,12]. However, in real clinical practice, even with bradycardia, single-chamber ventricular stimulants are sometimes used. In our study, in accordance with the recom- mendations, the regime of dual-chamber stimulation with frequency adap- tation of DDDR and single-chamber ventricular stimulation on demand VVI were most often established. The remaining pacemakers (AAI, AAIR, DDD, VVIR) were installed less often (7-16%). In accordance with the type of pace- maker, the pacemakers paced the in most of causes, much less often it remained sinus and less often there was atrial fibrillation.

Thus, according to the clinical and demographical data analysis, the fol- lowing conclusions could be made:

 1.   In the Republic of Bashkortostan, SSS was defined in the elderly (69.2 ±0.48    years) and more often in women than in men. The disease was more often associated with coronary heart disease (97.2%) and arterial hypertension (81.6%).

 2.      The variants of the syndrome were mainly bradycardia (63.4%), fol- lowed by SA blockade of 2d degree (13.2%), SA node failure (12.6%), 3d grade SA blockade (6.8%) and "tachy- brady" (3.0%).

Dualchamber with frequency ad-aptation and single-chamber ventricular pacemakers were often installed.

1.       Long-term follow-up monitoring will enable to evaluate the impact of different forms of SSS and types of pacemakers on the development of adverse cardiovascular diseases.

Research project has been supported by the grant of the President of the Russian Federation for young PhD MD- 16.7395 and Russian Humanitarian Sci- entific Foundation N 15-36-01255/15. No conflict of interests is declared.

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