A method for predicting the risk of sudden death after myocardial infarction

 

The invention relates to medicine, particularly cardiology. With the patient in the supine position record 5-minute intervals ECG random breath during active orthostatic test (AOP) and when performing tests with a deep breath (PGD). Calculate the indicators variational scope, standard and standard deviations, the proportion of very low frequencies in the total power spectrum at AOP and PGD and the amounts of shares of high and low frequencies in the total power spectrum with PGD. On the basis of the obtained values calculate the prognostic index of sudden death (PEVS). Value PEWS predict a high risk of sudden death. The method allows to increase the accuracy of the prediction. table 2. , 1 Il.

The invention relates to the field of medicine, particularly cardiology, and can be used in almost any medical facility.

Known methods of predicting the risk of sudden death (SU), which consists in determining the state of trigger mechanisms arrhythmic episode. These include: calculation of the ejection fraction of the left ventricle (PV), assessment of the severity of ventricular arrhythmias (INR) at the daily monitoring of the amended electrocardiogram C. F. Campbell. M. 1997. 87 S. and Malik M. Risk of Arrhythmia and sudden cardiac death. BMJ - Books: 2001].

A known method for predicting aircraft on the basis of determining the PV. The decrease in PV<40% is a sign of poor prognosis after myocardial infarction (mi) [Copie X., K. Hnatkova, Staunton, A., Fei L., Camm A. J., Malik M. Comparison of the predictiv power of increased heart rate wich that of depressed left ventricular ejection fraction and heart rate variability for risk t op after myocardial infarction results of a 2-year follow-up study. // Am. Coll. Cardiol. - 1996 - Vol. 27. - P. 270-276]. The study CAST was shown that the decrease in PV for every 10% is accompanied by a significant increase in mortality [Hallstrem A., Pratt C. M., Greene, H. L., et al. Relationship between heart failure, ejection fraction, arrhythmia supression and mortality: analysis of the cardiac arrhythmia suppression trial // JACC. 1995. - Vol. 13(1). - P. 1250-1257].

Calculation of PV, as a rule, by one of the following methods: echocardiography (ECHO KG), scintigraphy and ventriculography. Each of these methods requires expensive equipment, in addition, the last two are invasive, and the most accessible and non-invasive method - the ECHO-KG, the calculation of PV is based on the subjective view of the researcher about the boundaries of the endocardium and the cavity of the ventricle, which is especially important when measuring the geometry of the left ventricle (LV) after THEM [Silcocks P. B., Munro, J. F., R. P. Steeds, et al. Prognostic implications of qualitative assessment of l is based on viagenie INR at the daily ECG monitoring. It is believed that ventricular extrasystoles (IA) in an amount of not more than 10 in 1 h not essential and can be classified as benign [Bigger J. T. Jr., Fleiss J. L., R. E. Kleiger, J. P. Miller, L. M. Rolnitzky The Multicenter Postinfarction Research Group. The relationship among ventricular arrhythmias, left ventricular dysfunction, and mortality in the 2 years after myocardial infarction // Circulation. - 1984. - Vol. 69. - P. 250-258]. On the other hand, according to N. A. Mazur, if ventricular extrasystole occurs, albeit in small numbers, but with enough persistence, the patient's prognosis becomes less certain [Mazur N. A. Sudden death // Klin. The honey. - 1988. - So-Called. - S. 28-35] . Method of daily monitoring requires expensive and sensitive enough equipment, the duration of the study when it exceeds 24 hours, which is not suitable for screening patients at high risk of armed forces. In addition, it turned out, the sensitivity and specificity of both PV and INR were not very large [Multicenter Post Infarction Group. Mechanism of death and prevalence of myocardial ischemic symptoms in the terminal event after acute myocardial infarction // Am. J. Cardiol. - 1988. - Vol. 61. - P. 8-15].

A known method for predicting aircraft based on the analysis of indices of HRV. In the study of R. Pedretti et al. it is revealed that HRV gives more prognostic information than PV or wasn the Europ. Heart J. - 1996. - Vol. 7. - P. 131-141]. According to Fanell T. G. et al. reduced HRV has the highest sensitivity, specificity compared with other predictors SU [Farrell T. G. , Bashir y, Cripps T., et al. Risk t op for arrhythmic events in postinfarction patients based on heart rhythm variability, ambulatory electrocardiographic variables and the signal-averaged electrocardiogram // JACC. - 1991. - Vol. 18(5). - P. 687-697]. However, HRV, with independent prognostic value in determining the risk BC patients who underwent THEM, has relatively little predictive value [Bigger J. T., Fleiss J. L., L. M. Rolnitzky, Steinman R. C. The ability of several short-term measures of RR variability to predict mortality after myocardial infarction // Circulation. - 1993. - Vol. 88. - P. 927-934, R. E. Kleiger, J. P. Miller, Bigger J. T., Moss, A. J., The Multicenter Post-infarction Research Group. Decreased heart rate variability and its association with increased mortality after myocardial infarction // Am. J. Cardiol. - 1987. - Vol. 59. - P. 256-262] . It should be noted that the normal values of HRV in the absence of other known risk factors associated with very low risk of adverse outcome, while the combination of reduced HRV with them immediately increases the degree of predictive value. Work Bigger J. T. et al. it is shown that the combination of reduced VLF and more than 3 ventricular extrasystoles per hour increases the risk of cardiac death by up to 44%, in combination with PV<40% to 49% [Bigger J. T. Jr., Fleiss J. L., R. C. Steinman, the same time it is noticed, when SDNN>100 MS in the daily ECG recording frequency INR no significant effect on mortality [F. Lombardi , R. L. Verrier, Lown B. Relationship between sympathetic neural activity, coronary dynamics, and vulnerability to ventricular fibrillation during myocardial ischaemia and repermsion // Am. Heart. J. - 1983. - Vol. 105. - P. 958-965] . The majority of studies on restratification postinfarction patients based on the HRV performed using the 24-hour ECG recording, however, it was shown that the use of short records can be used for prescreening aircraft with similar sensitivity in comparison with 24 hours, but a lower specificity for identifying patients with a high risk of sun [Fei L., Malik M. Short - and long-term assessment of heart rate variability for postinfarction risk t op, In: Malik M., Camm A. J., eds. Heart Rate Variability // Armonk, NY. Fututa. - 1995. - P. 341-346] . The use of short records associated with fewer complications. First, it takes less time, and secondly, to 24-hour records should predyavlyat large requirements for analytical quality recording, filtering artifacts and, in addition, assumes the availability of expensive equipment or special laboratory, which is practically not always applicable, especially for screening patients at high risk.

As a prototype of the proposed sporovani risk of sudden death after THEM according to the results of HRV in patient lying on the back during random breath [J. T. Bigger Jr., Fleiss J. L., R. C. Steinman, L. M. Rolnitzky, R. E. Kleiger, J. N. Rottman Frequency domain measures of heart period variability and mortality after myocardial infarction // Circulation. - 1992. - Vol. 85. - P. 164-171]. This method can be used to prescreening patients with a high risk of sun [Task Force of the European Society of Cardiology and the North American Society of Pacing and Electrophysiology. Heart Rate Variability. Standards of Measurements, Physiological Interpretation, and Clinical Use // Circulation. - 1996. - Vol. 93. - P. 1043-1065]. However, HRV, with independent prognostic value in determining the risk BC patients who underwent THEM, has relatively little predictive value [Bigger J. T., Fleiss J. L., L. M. Rolnitzky, Steinman R. C. The ability of several short-term measures of RR variability to predict mortality after myocardial infarction // Circulation. - 1993. - Vol. 88. - P. 927-934, R. E. Kleiger, J. P. Miller, Bigger J. T., Moss, A. J. The Multicenter Post-infarction Research Group. Decreased heart rate variability and its association with increased mortality after myocardial infarction // Am. J. Cardiol. - 1987. - Vol. 59. - P. 256-262], which significantly limits the opportunities for risk stratification of patsientov after THEM.

Table 2 presents the sensitivity, specificity, predictive value positive and a negative result and the prediction accuracy obtained by the use in risk stratification after their figures high frequency resolution in the supine position during voluntary breathing. The highest sensitivity and specificity obtained is Salo attention, all indicators showed a high predictive value of a negative result and at the same time, predictive value of a positive result was low with a maximum of TR<415,9 MS2of 13.7%. The forecasting accuracy of each of these indicators were low. The highest was registered for % VLF - 57.8 per cent, the lowest for TR - 33,3%.

The objective of the invention is to develop a method for predicting the risk of aircraft after THEM, improve the accuracy of prediction.

The problem is solved in that the assessment of HRV exercise for 5-minute ECG records in the patient lying on the back during random breath, characterized in, and the patient lying when performing tests with deep breathing and during active orthostatic test. This parasympathetic tonus of the vegetative nervous system is evaluated on the dynamics of the sum of the shares of high and low frequencies in the total spectral power (%SF=%LF+%HF), and forecast risk VS exercise formula PEWS=-0,03X1-0,23X2+3X3+1,44X4 +4,65X5+of 5.05X6, where X1 - dRR (variation RASMAN); X3 - RMSSD(AOP) (standard deviation when conducting an active orthostatic probe, 1 - increase compared to the initial value, 2 - decreasing); X4 - %VLF(AOP) (the proportion of very low frequencies in the total power of the spectrum when carrying out an active orthostatic probe, 1 - increase compared to the initial value, 2 - decreasing); X5 - %VLF(PGD) (the proportion of very low frequencies in the total power spectrum of the test with a deep breath, 1 - when you increase compared to the initial value, 2 - decreasing); X6 - %SF(PGD) (share of total frequency total power of the spectrum when carrying out an active orthostatic probe, 1 - increase compared to the initial value, 2 - decreasing), and when the value of PIS>11,47 predict a high risk of sudden death.

The method is as follows. Indices of HRV were obtained when the analysis of 5-minute ECG records in the patient lying on the back (original position), and the patient lying when performing tests with a deep breath (PGD) and during active orthostatic test (AOP). To assess the predictive values of HRV following indicators are used: the position is to AOP RMSSD, MS (standard deviation) and %VLF, % (dynamics of the share of very low frequencies). During PGD - %VLF, % (dynamics of the share of very low frequencies) and %SF, % (dynamics of the share of the total frequency). Regression coefficients, the relative risk and confidence intervals for these parameters are presented in table 1. The above values are substituted in the formula prognostic index sudden death (PIVS): PIS=-0,03X1-0,23X2+3X3+1,44X4+4,65X5+of 5.05X6,
where X1 - dRR; x2 - SD; X3 - RMSSD during AOP; X4 - %VLF when AOP; X5 - %VLF when PGD; X6 - %SF with PGD.

Example 1.

Patient S. , 56, and/b 8490, were treated in the city hospital 2 in the Cardiology Department with 2 23.03.01 on 20.04.01, the DIAGNOSIS of CHD. Acute myocardial infarction, anterior Q myocardial infarction, 30.03.01. Ventricular extrasystole III class Lown. CH III F. to NYHA.

Hypertension II Art.

Data instrumental study:
The clinical analysis of blood from 30.03.01: Eg - 3,4410/l; b - 115 g/l; CPU - 1,0; Ht - 35%; Tr - 55510/l;. Les - 8,510/l; limp. 22%; Mont. - 6%; neutral. - 70%; p/I - 2%; with/I - 68%; EOS. 2%; databases. - 0%; ESR - 43 mm/h the bin General 4.8 Ámol/l, CPK - 1238 U/l, lactate dehydrogenase - 588 U/L.

ECG analysis 26.03.01, 10.04.01, sinus Rhythm. On the background of the original normal ECG from 26.03.01, ECG from 30.03.01 there were signs of necrosis (QS V1-V4, pathological teeth Q V5-V6, II, III, AVF). Elevation of the ST segment in the same derivations without dynamics is stored on 09.04.01, (10 days). "Frozen" ECG curve may reflect the vastness of the lesion or the development of aneurysms of the left ventricle.

ECG from 16.04.01, sinus Rhythm, heart rate 93 min. series ECG acute circulatory dynamics Q-myocardial infarction, probably with the formation of aneurysms literary journals

Echocardiography (06.04.01)
Sizes: LG - 52 mm; Lis - 43 mm; annuals - 9 mm; LC - 11 mm; SC - 33 mm; PL - 40 mm; PJ - 27 mm; PP - 42 mm; LA not measured. Function: FU-17%; PV(in)-36%; valves: mitral: regurgitation 0-1 Art.

Cavity is not expanded. The myocardium is not thickened. Dyskinesia annuals, akinesia top. We cannot exclude the presence of thrombus in the region of the apex. The overall contractility of the left ventricle is reduced. MK sash sealed. The aorta and aortic populonia thickened. Right departments is not extended. The pressure in the pulmonary artery to measure failed. The pericardium without features. Conclusion: Focal lesion of the left ventricle.

Day. ECG monitoring from 10.06.01: CSMP - 53 min; Cssmax - 88 is dachkova arrythmia: single at number 3 in the hour and ventricular premature beats: single polymorphic in the number of 18 per hour. On the background of the source changes convincing signs of myocardial ischemia is not defined.

Heart rate variability at rest, during voluntary breath:
RR - 876 MS, AMO - 81%, dRR - 96 MS, SD - 18 MS, CV of 2.1%, RMSSD was 8.8 MS2, NN50 - 0 online, LF/HF - 4,5, LFnu - 81,9 nu, HFnu - 18,1 nu, LF - 82 MS2, HF - 18 MS2, VLF - 225 MS2, TP - 325 MS2, %LF IS 25.2%, %HF - 5,5%, %VLF - 69,3%, %SF - 30.7 PER CENT.

Conclusion: Sympathicotonia involving humoral-metabolic regulation.

Inhibition of parasympathetic influences on the heart rhythm.

Heart rate variability during AOP
RR - 786 MS, AMO - 66%, dRR - 168 MS, SD - 24 MS, CV of 3.1%, RMSSD - 10,7 MS2, NN50 - 1 online, LF/HF - 5,5, LFnu - 84,7 nu, HFnu and 15.3 nu, LF - 293 MS2, HF - 53 MS2, VLF - 232 MS2, TR - 578 MS2, %LF - 50,7%, %HF - 9,2%, %VLF - 40,1%.

Conclusion: the Increase of sympathetic influences and tone of the vagus nerve. The answer to the test at the IA class.

Heart rate variability when conducting PGD
RR - 915 MS, AMO - 71%, dRR - 124 MS, SD - 22 MS, CV - 2,4%, RMSSD - of 12.8 MS2, NN50 - 1 online, LF/HF ratio of 1.8. LFnu - 64,7 nu. HFnu - 35,3 nu, LF - 146 MC2, HF - 79 MS2, VLF - 142 MS2, TR - 367 MS2, %LF OF 39.8%, %HF - 21,5%, %VLF - 38,7%, %SF - 61,3%.

Conclusion: Strengthening the parasympathetic. The answer to the test class I.

The calculation of PIS:
-0,0396-0,231=7,12
Conclusion: The patient has anterior Q, complicated by heart failure class III according to NYHA, According to the ECHO-KG - revealed decreased EF component 36%, as well as a local violation of LV contractility, possibly reflecting the formation of acute aneurysm of the left ventricle. According to the results of daily monitoring of ECG was determined ventricular extrasystole level III class Lown. In the study of HRV at rest metrics such as SD, RR, dRR, HFnu and TR were less than the values defined for the characteristics of suddenly deceased patients, a LFnu more. Thus, the patient revealed a large group of signs of poor prognosis after THEM in relation to the sun and he had to be identified as high risk. When conducting vegetative samples revealed that variant to the AOP (class IA) and PGD (class I) consistent with low risk of aircraft. Thus, on the basis of available data it is not possible to accurately determine the prognosis for this patient for this purpose was calculated PEWS, which was 7,12 that less than a critical value 11,47. Thus, the calculated individual risk for the patient turned out to be small. This is confirmed by the fact that within 14 months after THEY Bo the division of cardiology 2: 01.03.01 on 06.04.01,

THE DIAGNOSIS OF CHD. Acute myocardial infarction penetrating, peredneperegorodochnoj from 01.03.01, relapse from 19.03.01. Early post-infarction angina. Postinfarction cardiosclerosis (from 09.2000 year). Chronic left ventricular aneurysm. Ventricular extrasystole III class Lown. NC II F. to. according to NYHA. Hypertension II senior Obliterating atherosclerosis of the lower extremities. ICD. the concretions of the left kidney.

Data instrumental study:
The clinical analysis of blood from 02.03.01: Eg - 3,8610/l; b - 112 g/l; CPU - 0,87; Ht - 28%; Tr - 21010/l; Le - 12,310/l; limp. 18%; Mont. - 15%; neutral. - 67%; p/I - 11%; s/I - 56%; EOS. - 0%; databases. - 0%; ESR 55 mm/h

Biochemical blood test: 01.03.01: ALT - 43 U/L. ACT-186 U/l, total protein - to 77.7 g/l, albumin - 46,02 g/l, prothrombin 121, 1million%, cholesterol - 6.4 mmol/l, triglycerides - 3.1 mmol/l, glucose - 6.8 mmol/l, LDL - 53%, bilirubin total of 11.2 Ámol/l, CPK - 1671 U/l, lactate dehydrogenase - 1625 U/l,
ECG analysis: Sinus rhythm. Blockade of the anterior branch of the left bundle branch. Signs excentric types. Acute focal changes in peredneperegorodochnoj region LV from 13.03.01, ECG from 19.03.01 relapse of acute penetrating peredneperegorodochnoj infactory: LG - 52 mm; Lis - 40 mm; annuals - 11 mm; LC - 12 mm; SC - 37 mm; PL - 42 mm; PJ - 28 mm; PP - 43 mm; LA - 23 mm; FU - 22%; PV(b) - 46%.

Valves: mitral: regurgitation 1 tbsp.; aortic: regurgitation 0-1 Art. ; T1/2 - 600 MS; tricuspid: regurgitation 0-1 Art.; slightly enlarged left atrium. Thickened rear wall of the left ventricle. Akinesia annuals. Akinesia with elements dyskinesia top. The overall contractility of the left ventricle is reduced. Diastolic function is impaired - 1 type. Fold thickened mitral valve, expressed fibrocalculous. The aorta and aortic populonia sclerotic (fibrous). Calcification of the aortic wall boundary calinos of paleloni. Right departments is not extended. The pressure in the pulmonary artery to measure failed. The pericardium without features. Conclusion: focal lesion of the left ventricle. We cannot exclude the presence of chronic aneurysm at the apex.

Monitoring of ECG: 31.03.01 rate environments. 65 beats./min, Cscmp 44 beats./min, Cssmax. 111 beats./min On the background of sinus rhythm were recorded: atrial extrasystoles - ground, single, uniformly rare, on average, up 22 per hour, 1 episode of atrial tachycardia with heart rate of 120 beats. /min Ventricular extrasystoles single, polymorphic, polytopia, on average, up to 3-4 minutes, occasionally OYe random breath:
RR - 879 MS, AMO - 79%, dRR - 122 MS, SD - 24 MS, CV of 2.7%, RMSSD and 15.3 MS2, NN50 - 3 online, LF/HF - 7,7, LFnu and 88.5 nu, HFnu - 11,5 nu, LF - 192 MS2, HF - 25 MS2, VLF - 151 MS2, TP - 368 MS2, %LF - 52,2%, %HF IS 6.8%, %VLF - 41%, %SF - 59%. Conclusion: the Absolute sympathicotonia involving humoral-metabolic systems. Significant inhibition of parasympathetic regulation.

Heart rate variability during AOP
RR - 728 MS, Amo, 92%, dRR - 64 MS, SD - 13 MS, CV of 1.8%, RMSSD and 6.2 MS2, NN50 - 0 online, LF/HF - 3,1, LFnu - 75,8 nu, HFnu - 24,2 nu, LF - 25 MS2, HF - 8 MS2, VLF - 112 MS2, TR - 145 MS2, %LF IS 17.2%, %HF - 5,5%, %VLF - 77.3 PER CENT.

Conclusion: the Transition regulation of heart rate in humoral-metabolic level. The answer to the test at PW-class.

Heart rate variability when conducting PGD
RR - 903 MS, Amo, 56%, dRR - 140 MS, SD - 25 MS, CV - 2,8%, RMSSD and 8.1 MS2, NN50 - 2 online, LF/HF - 22,9, LFnu - 95,8 nu, HFnu - 4,2 nu, LF - 200 MS2, HF - 8 MS2, VLF - 386 MS2, TR - 594 MS2, %LF - 33,7%, %HF - 1,4%, %VLF - 64,9%, %SF - 35.1 PER CENT.

Conclusion: Inhibition of the parasympathetic activation of the humoral-metabolic components. The answer to the test for class II.

The calculation of PIS:
-0,03122-0,2324+32+1,441+4,65

The information content of the index was tested on an independent (control) group of patients (100 people), randomized simultaneously with the training group. In assessing the effectiveness of the proposed index has been shown that the correspondence between the forecast and the actual outcome after THEM towards the sun - the accuracy was 93%, sensitivity was 85.7 percent, specificity was 93.6%, a PPV of 50%, and OPT - 98,9%. Correlation level PIWS with endpoints observations Pearson was 0,89 at p=0.001. The increase in prediction accuracy of aircraft developed by the method that is most probably due to the inclusion in the estimation not only of the baseline tonus of the vegetative nervous system, but also available for hidden faults that occur only upon presentation of physiological stress - vegetative samples [Wayne A. M. Autonomic disorders - M.: Medicine in the rage presents survival curves for all patients after THEM, divided largest PEWS to group index >11,47 and <11,47. As can be seen from the diagram, survival curves was statistically significant (p=0,034) differed in the frequency of occurrence of the armed forces. In addition, pay attention that the greatest risk of BC in patients with PIS >11,47 was noted during the first 11 months after THEM, reaching 15%. At the same time in patients with PIS >11,47 was only 3%.

Thus, the proposed forecasting method allows to increase the accuracy of the prediction of 35.2 and 59.7% (average 48.4%) compared to the prototype.


Claims

A method for predicting the risk of sudden death after myocardial infarction by assessing heart rate variability in 5-minute ECG records in the patient lying on the back during random breath, characterized in that the evaluation of heart rate variability is additionally carried out during active orthostatic test (AOP), and the patient lying when performing tests with a deep breath (PGD), while assessing parasympathetic tonus of the vegetative nervous system on the dynamics of the amount of shares high (HF) and low frequency (LF) in the total spectral power (%SF=%LF+%HF)and forecast the risk of sudden death (PIVS) ASSMD>X3+1,44X4+4,65X5+of 5.05X6,

where X1 - dRR (variational sweep in the supine position during voluntary breathing);

X2 - SD (standard deviation in the supine position during voluntary breathing);

X3 - RMSSD (AOP) (standard deviation when conducting an active orthostatic probe, 1 - increase compared to the initial value, 2 - decreasing);

X4 - % VLF (AOP) (the proportion of very low frequencies in the total power of the spectrum when carrying out an active orthostatic probe, 1 - increase compared to the initial value, 2 - decreasing);

X5 - %VLF (PGD) ( the proportion of very low frequencies in the total power spectrum of the test with a deep breath, 1 with increase in comparison with the initial value, 2 - decreasing);

X6 -%SF (PGD) (share of total frequency total power spectrum of the test with a deep breath, 1 with increase in comparison with the initial value, 2 - decreasing),

and when is PIVS more 11,47 predict a high risk of sudden death.

 

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FIELD: medicine.

SUBSTANCE: method involves recording heart beat rate and systolic arterial blood pressure before and after two-stage exercise stress. The first stage is of 50 W within 3 min and the second one is of 75 W during 2 min. Patient rest pause is available between loading stages to recover initial heart beat rate. Prognostic estimation of cardiopulmonary complications is carried out with mathematical formula applied.

EFFECT: reduced risk of complications in performing tests.

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