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Akkiev Bobomurod Toshpulatovich, Kurbanov Ravshanbek Davletovich, Abdullaev Timur Atanazarovich, The Republican Specialized Center of Cardiology E-mail: [email protected]
INTERRELATION OF THE HEART RATE VARIABILITY WITH VENTRICLE EXTRASYSTOLE IN LEFT VENTRICLE SYSTOLIC DYSFUNCTION OF THE PATIENTS WITH MYOCARDIAL INFARCTION
Abstract:
Objectives: The aim of our research was to study interrelations between heart rate variability and ventricle extrasystole in systolic dysfunction of the left ventricle in the patients with acute Q-wave myocardial infarction.
Study design: This study includes 84 male patients with acute Q-wave myocardial infarction. All the patients underwent echocardiography on the 10-14 day of disease in order to estimate systolic function of the left ventricle, ECG Holter monitoring with measurement of heart rate variability and ventricular extrasystole. All patients received standard therapy including ^-blockers, antiagregants, antiarrhythmic agents, aldosteron antagonists, ACE inhibitors, calcium antagonists, nitrates, statins.
Results: After the first clinical-functional examination there was found systolic dysfunction of the left ventricle in 23 (27,4%) patients. The development of the early left ventricle remodeling, acute heart failure, increasing level of inflammation markers were noted more frequently in this group of patients. We revealed that interrelation between heart rate variability and ventricular arrhythmia had reliable character in systolic dysfunction.
Conclusion: In the group of patients with systolic dysfunction on the 10-14 day of acute Q-wave myocardial infarction there was reliably registered more often potentially dangerous ventricle arrhythmia and lower heart rate variability connected with dysbalance of sympathetic and parasympathetic part of the autonomous nervous system. There has been established reliable interrelation between frequency of development of potentially dangerous ventricular arrhythmia and lower parameters of the heart rate variability in the patients with systolic dysfunction.
Keywords: myocardial infarction, heart rate variability, ventricular extrasystole, left ventricle, systolic dysfunction, male patients.
Introduction ing into consideration the importance of this problem,
It is well known that during the first year after the great attention has been paid to the search for pre-
myocardial infarction (MI) 6.5-11% of patients die dictors of the fatal arrhythmia and also stratification of
and about half of them die suddenly [1, 2, 5, 6]. The the patients with ischemic heart disease (IHD) with
frequency of sudden cardiac death (SCD) accounts regard to the risk severity of SCD. The current predic-
for 0.36-1.28 per 1000 persons a year [2, 5, 6], and tors include demographic indicators, lower fraction of
survival during a year in SCD (after successful reani- the left ventricle ejection (LV FE), reduction of heart
mation measures against cardiac clinical death) is not rate variability (HRV), ventricular rhythm disturbance
higher than 15-20% by the various data [1, 7, 8]. Tak- (VRD) and others [5, 6, 7, 8].
We have not found data in the literature about correlation of the heart rate variability and ventricular extrasystoles in systolic dysfunction of the left ventricle in the patients with myocardial infarction.
According to the above-mentioned the purpose of our report is to study correlation between heart rate variability and ventricular extrasystole in systolic dysfunction of the left ventricle in the patients with acute Q-wave myocardial infarction.
Material and methods
Following the purposeful tasks we examined 84 male patients with primary Q-wave myocardial infarction of the age from 29 to 65 years, (52 ± 8.6 years). Diagnosis was established on the basis of WHO criteria at presence of two or three signs: special attack of anginous pain or its equivalent for 30 minutes, appearance of pathological Q or QS in two or more leads of ECG, creatininphosphakinase prevailed upper normal level more than 2 times. All patients gave written consents for participation in this investigation. The patients with the following complications of the myocardial infarction and accompanied pathology were excluded from the study: ciliary arrhythmia, AV-blockade of stage II-III, arterial hypotension (AP < < 90/60 mm Hg), age above 65 years, chronic pulmonary diseases with marked respiratory insufficiency and symptoms of bronchospasm, diabetes mellitus at the stage of compensation, malignant arterial hypertension, oncological diseases, consequences of the acute cerebral circulation disorders and echonegative patients.
All patients received standard therapy (^-blockers, antiagregants, antiarrhythmics, aldosteron antagonists, ACE inhibitors, calcium antagonists, nitrates, statins).
The patients were performed EchoCG on the echo-cardiograph "Solnoline Versa Pro" (Siemens, Germany) on the basis of therapy performed on the 10-14 day after acute myocardial infarction; evaluation of the LV contractility was carried out with use of its fraction of ejection: FE = ((EDV - ESV)/EDV)*100%.
According to the recommendations of 2010, the third revision, of the Society of Experts on Heart Failure (SEHF) the stage of systolic heart failure is measured by the level of findings of the fraction of ejection: lowered - FE < 40%; "gloaming zone" - FE40-50%; preserved - LV FE > 50%. Among the studied patients the men with marked stage of heart failure were very few. In this connection we divided the patients into two groups: the group with marked stage of systolic dysfunction included the patients with LV FE < 45%, and the group with preserved function of the left ventricle consisted of the patients with LV FE > 45%.
The ECG Holter monitoring (HM) was performed with use of apparatus "Cerdio sens+" (HAI-MEDIKA, the Ukraine) for measurement of VE and HRV. The ventricle extrasystole (VE) was characterized by traditional classification of B. Lown (1971) and prognostic classification of J. Bigger (1982). The interpretation of the HRV was made according to the recommendation of working group of the European Society of Cardiologists and the North-American Society of Stimulation and Electrophysiology (1996). For evaluation of HRV there were used the following time and spectral parameters:
Table 1.
SDNN (ms) Standard deviation of all intervals N-N
ADANN (ms) Standard deviation of mean values of intervals N - N, calculated by 5-minute intervals during whole recording
pNN50 (%) Value NN50, divided by total number of intervals N - N
TP (ms2) Total power of all intervals R - R
LF (ms2) Power in diapason of low frequencies (0.04-0.15 Htz)
HF (ms2) Power in diapason of high frequencies (0.15-0.4 Htz)
LF/HF Ratio of low frequency to high frequency component of the spectrum
Mathematic processing of the results obtained was as well as Biostat. For analysis of reliability of differences made on the personal computer "Pentium IV" with use between qualitative signs the criterion x2 was used. The of pocket of programs STATISTICA version 6 "StatSoft" inter-group comparative analysis ofquantitative values was
performed in two groups with use of criterion Student t. All values were presented as arithmetical mean ± standard deviation (M ± SD), and sign changes as mean change (± %). The differences in p < 0,05 were accepted as reliable.
Results
The complex clinical-functional examination was carried out on 84 patients (Table 1). While studying histories It was revealed that 55 (65,4%) patients suffered from HD before onset of MI; DM was revealed both in the history and primary in 16 (19%) patients. RPIS was found in 34(40,4%) patients. Analysis of MI development in acute and subacute period showed that
in 47(55.9%) cases there were observed lesions of the anterior wall, and in the rest 37(44%) of cases in the lower wall. In 40(47.6%) patients the progressing of acute period of disease was complicated by development of clinical evidences of acute heart failure (HF) (Killip, class II-IV) including 26 (65%) cases of class II, 11 (27.5%) cases of class III, 3(7.5%) cases of class IV (cardiogenic shock). Clinical evidences of CHF II "A" stage were revealed in 46(54.7%), of II "B" stage in 1(1.1%) patients. It is interesting that of them in 33 (39%) patients the symptoms of CHF were correlated to FC I-II by NYHA classification, and in 14 (16.4%) patients - to CHF FC III-IV.
Table 2.- Clinical characteristics of the studied patients
Characteristic Absolute number (n=84) %
History HD 55 65.4
EPIS 34 40.4
Histories and primary defined DM 16 19
Anterior MI 47 55.9
Lower MI 37 44
AHF by Killip (I-II) 26 31
AHF by Killip (III-IV) 14 16.6
CHF IIA'st. FC I-II by NYHA 33 39
CHF II "A" st. FC III-IV by NYHA 13 15.4
CHF II "B" st. FC III-IV by NYHA 1 1.1
According to the initial data of EchoCG the patients were divided into 2 groups. Group 1 included 23 (27.3%) patients with systolic dysfunction LV FE < 45%. The rest 61 (72.7%) patients entered group 2 LV FE> 45% (Table 2). The patients of the comparative groups have no reliable differences by age, 53.74 ± 1.3 years and 51.24 ± 1.4 years (p < 0.05), HD in histories was noted in 14 (60.8%) and 41
Table 2.- Comparative characteristic of the
(67.2%) patients in group I and II, respectively (x2 = =0.08; P = 0.7), DM type 2 was revealed in 5 (21.7%) and in 11 (18%) patients in group I and II, respectively (x2 = 0.006; P = 0.9). According to data of ECG and EchoCG the anterior localization of MI (x2 = =1.68; P = 0.19) was register not reliably in the patients from group 1, and in group II the lower localization (x2 = 1.68; P = 0.19) was found, respectively.
patients with different fraction of ejection.
Parameters Group I (n = 23) LVFE < 45% abs.(%) or M±m Group II (n = 61) LVFE > 45% abs.(%) or M ± m f; p
1 2 3 4
Age. years 53.74 ± 1.3 51.34 ± 1.4 > 0.05
HD 14 (60.8) 41 (67.2) £ = 0.08; P = 0.7
EPIS 10 (43.4) 24 (39.3) X2 = 0.0009; P = 0.9
DM 5(21.7) 11(18) X2 = 0.006; P = 0.9
1 2 3 4
CHF II «A» st. FC I-II by NYHA 12 (52.1) 21 (34.4) X2 = 1.5; P = 0.2
CHF II «A» st. FC III-IV by NYHA 5 (21.7) 8(13.1) X2 = 0.4; P = 0.52
CHF II «B» st. FC III-IV by NYHA 1 (4.3) 0 £ = 0.26; P = 0.61
AHF by Killip 19 (82.6) 21 (34.4) X2 = 13.6; P = 0.000
LV early remodelling 9 (39.1) 8 (13.1) X2 = 5.48; P= 0.02
LV FE (%) 39.52 ± 1.6 57.5 ± 1.9 < 0.001
LV anterior wall 16 (69.5) 31(50.8) X2 = 1.68;
LV posterior wall 7(30.4) 30 (49.1) P = 0.19
C-reactive protein mg/l 8. 4±1. 1 5. 6 ± 0. 7 < 0. 05
In the comparative groups the quality of the patients with potentially hazardous ventricle arrhythmia (PHVA) is reliably different and accounts for 21 (91,3%) and 3 (21.3%), respectively in group I and II (^2 = 31.1; P = 0.000). Besides, high grade VE: by Lown-Wolf III
(12-52.1% and 9-14.7%, x2 = 10.5; P = 0.0010, IVA (13-56,5% and 7-11,4%, i2 = 16,3; P = 0.000), IVB (7-30.4% and 3-4.9%, x2 = 8.08; P = 0.004) were reliably recorded in group 1 (Table 3).
Table 3.- Findings of ECG HM in the patients of the compared groups
Parameters Group I (n = 23) rpynna II (n = 61) x2; p
Abs(%) M ± SD Abs (%) M ± SD
PDVA 21(91.3) 13 (21.3) x2 = 31. 1 P = 0. 000
VE by Lown-Wolf III 12 (52. 1) 9 (14. 7) x2 = 10. 5 P = 0. 001
IV A Cl. 13 (56. 5) 7 (11. 4) x2 = 16. 3 P = 0. 000
IV B Cl. 7 (30. 4) 3 (4. 9) x2 = 8. 08 P = 0. 004
V Cl. 1 (4. 3) 1(1. 6) x2 = 0. 006 P = 0. 94
SDNN ms 91. 57 ± 32. 7 107. 7 ± 28. 89 < 0. 05
SDANN ms 80. 52 ± 27. 0 96. 8 ± 25. 8 < 0. 05
pNN50% 5. 85 ± 1. 1 8. 65 ± 1. 0 < 0. 05
TP ms2 1458. 3 ± 314. 8 1583. 7 ± 209. 4 > 0. 05
LF ms2 414. 6 ± 18. 3 449. 7 ± 18. 8 > 0. 05
HF ms2 154. 3 ± 18. 9 197. 4 ± 16. 7 < 0. 05
LF/HF 2. 82 ± 0. 91 2. 6 ± 1. 16 > 0. 05
Discussion
The question about prognostic value of the myocardium infarction localization is still discussing: a number of authors observed the higher level of frequency of "end points" (cardiac death, repeated MI, unstable angina
pectoris) at the anterior than at lower MI [9]. During observation of the patients having MI it was established that frequency of postinfarction complications in lower MI was 2 times less that in anterior myocardium infarction [11]. At the same time analyzing 5-year survival of
the patients with MI there was no revealed significant differences by the level of survival in different localization of the process (in anterior - 90%, in lower - 93%) [10]. In opinion of other authors localization of MI had no independent prognostic meaning and character of disease clinical course is mainly determined by the stage of myocardium contractility reduction [9]. To the present time the sufficiently determined opinion about prognostic role of left ventricle dysfunction in myocardium infarction has been accepted. Brugada P., analyzing prognostic role of 70 clinical signs in 2-year observation identified HF III functional class by NYHA classification as independent predictor of sudden cardiac death (SCD) [12]. It should be noted that by the results of our study in group of patients with evident systolic dysfunction in the stationary period of myocardial infarction the development of CHF (x2 = 13.6; p = 0.000) and early LV remodelling (x2 = 5.48; p = 0.02) were registered reliably more often. Besides, biochemical analysis showed reliably higher level of CRB in group 1, than in group II (8.4 ± 1.1 mg/l, and 5.6 ± 0.7 mg/l, respectively in group I and II,p < 0.05).
At present time the opinion has become widely distributed that reduction of the myocardial contractility is the predictor for ventricular arrhythmia, and the frequency of identification of VA high grades dependents on the degree of cardiac muscle dysfunction. There was revealed reverse correlation between VA severity degree and volume of the left ventricular fraction of ejection [13]. This is confirmed by the more frequent identification of the complex types of the VE in the patients having MI in the history in comparison with patients without MI, as well as in the patients with large focus and especially transmural MI [14].
The dysbalance between sympathetic and para-sympathetic parts of the autonomous nervous system occurring in ischemic heart disease and acute myocardial infarction resulted in reduction of electric rhythmicity of the myocardial functioning. In this case the process of distribution of the depolarization wave, inducing myocardial contraction, has become unstable. Sympathetic effect provoke occurrence of dangerous ventricular arrhythmia, vagus nerves play defensive role. It is necessary to note that in out investigation analysis of the parameters
of heart rate variability also showed reliable differences between levels in the comparative groups. So, the mean level of SDNN was 91.57 ± 32.7 ms and 107.7 ± 28.8 ms in group II (p < 0.05). SDANN mean level accounted for 80.5 ± 27 mc and 96.8 ± 25.8 mc in group I and II, respectively, (p < 0.05). Analysis of the frequency parameters was as follows: high frequency power was 154.3 ± ± 18.9 and 197.4 ± 16.7 ms2 in group I and II, respectively, (p < 0.05). The parameter, characterizing indirectly balance between sympathetic and parasympathetic systems was 2.82 ± 0.9 and 2.6 ± 1.2 in group I and II, respectively (p < 0.05). According to data of some authors in lowering SD less than 50 msec the risk of development of dangerous ventricular arrhythmia (FV, VT) increases sharply. Decrease in the total spectrum power (it is proportional to SD quadrate which occurs mainly due to decrease in HF power at relative increase in LF power. If normal proportion LF/HF is 2-3, then in AM it may increase to 10 [15].
Conclusions
1. The obvious systolic dysfunction of the left ventricle (FE < 45%) develops in more than one fourth of patients on the background of standard therapy on the 10-14 day of acute Q-wave myocardial infarction.
2. In the patients with LV systolic dysfunction the development of acute heart failure, early remodeling of LV were observed reliably more often and the level of C-reactive protein was reliably high to the end of stationary period of acute MI treatment.
3. The potentially dangerous ventricular arrhythmia was observed reliably more often and lower HRV connected with dysbalance of sympathetic and parasympathetic parts of the autonomous nervous system in the group ofpatients with systolic dysfunction on the 10-14 day of acute myocardial infarction.
4. There has been established reliable relationship between frequency of the PDVA development and lower HRV findings in the patients with systolic dysfunction.
Limitations of the study
The sample size was relatively small and conducted at a single center. Therefore, future large multi-center prospective cohort studies are needed to address this issue.
Conflict-of-interest issues regarding the authorship or article: None declared.
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