Residual ST-T ECG Mapping Abnormalities
and Late Potential Parameters
After Coronary Intervention

Slavomira Filipova^a, Dana Skultetyova^a, Milan Tysler^b, and Michaela Turzova^b

^aDepartment of Cardiology Institute of Cardiovascular Diseases and Slovak Health University, Bratislava, Slovakia ^bInstitute of Measurement Science, Slovak Academy of Sciences, Bratislava, Slovakia

Correrspondence: S Filipova, Department of Cardiology, Slovak Health University and Slovak Institute of Cardiovascular Diseases,
Pod Krasnou horkou 1, SK 833 48 Bratislava, Slovakia.
E-mail: filipova@susch.sk, phone +421 2 59320282, fax +421 2 55424049

1.    Introduction

After MI, the necrotic tissue is replaced by fibrous tissue. This process may disrupt the normal architecture of human myocardium and may have devastating consequences on the passage of the ventricular depolarization and repolarization process [Kozlikova, 1994; Kozlikova et al., 1995; Filipova, 1997]. Patients after myocardial infarction (MI) with scar formation remain at risk for life-threatening complications, especially for ventricular tachycardia and ventricular fibrillation. Noninvasive ECG methods as signal-averaged ECG (ventricular late potentials = VLP) and isointegral ECG body surface mapping (IBSPM) can contribute to the noninvasive risk stratification of patients after acute myocardial infarction.

The aim of study. The persistence of abnormal parameters of VLP may be useful indicator of pre-sence of the significant residual ischemia after myocardial infarction and the predictor of arrhythmic events in post-MI patients treated or non-treated interventionally (PTCA or CABG). The departure IBSPM represents the noninvasive precise ECG method for detection of residual myocardial ischemia. The departure mapping procedure quantifies the abnormalities in cardioelectric field (CEF). We tested the hypothesis that ST-T abnormalities (indicated by the departure IBSPM) may be connected with the abnormal parameters of VLP (fQRSd, RMS40v, HFLAd) in patients after well-documented myocardial infarction.

2.  Material and Methods

Follow-up of clinical examination, 12-lead ECG, IBSPM with departuring process for CEF abnormalities [Tysler et al., 1999; Hoekema et al., 1999] and VLPs were realized in 180 patients after the first acute myocardial infarction and in 74 control patients. The 1^st examination was done from 14 days to 4 months after the onset of coronary event, the 2^nd examination from 5 to 16 months after the first one.

Patients were treated:

a)   interventionally (Group 1) - 72 pts (49 patients after PTCA created subgroup 1a; 23 patients after bypass surgery created subgroup 1b);

b)   conventionally (Group 2) – 108 patients after i.v. thrombolytic therapy with streptokinase or anti-coagulant i.v. therapy (heparin) without subsequent interventions.

We used the control group (Group C) of 74 well-documented patients with chronic form of coro-nary heart disease without previous myocardial infarction attack, after the complete cardiologic examination [Filipova et al., 1995]. These patients were evaluated for testing of the variability of 12-lead ECG patterns, VLP parameters and for creating IBSPM “norms” (etalons) for departure mapping.

3.  Results

1) There were not found the correlations between voltage in departure IBSPM ST-T data and VLP parameters for the 1^st and 2^nd examinations in the patients after MI without the intervention therapy.

2) The normal VLP values during the 1^st examination were not changed (worsened) significantly after the intervention therapy (according the 2^nd examination data) in all studied groups.

3) The significant residual ischemia in ST-T departure IBSPM was connected with persisting of the abnormal time values of VLP in groups 1a, 1b and 2. The most pronounced correlation between ab-normal ST-T parameters of IBSPM (more than –2 SD) and abnormal VLP parameter fQRSd was found in the group 2.

4) It was found the significant improvement of abnormal VLPs during the follow-up period in the both interventionally treated subgroups (1a and 1b) (p < 0.01).

5) Significantly more frequent of serious cardiac events ( arrhythmia class Lown III-IV in EKG Holter data, documented non-sustained ventricular tachycardia, ventricular fibrillation, sudden cardiac death, new BBB, urgent implantation of PM) were situated in group 2, compared with group 1 (p < 0.05).

4.  Discussion and Conclusions

According our results the non-invasive assessment of residual local ischemia after acute myocardial infarction according to IBSPM of ST-T period is significant predictive factor for the future cardiac events.

Abnormal VLP parameters are significantly connected with the persistence of local residual ische-mia determined by the used mapping method. The successful intervention therapy has significant influence not only on the repolarization part of cardioelectric field (according to ST-T departure isointegral BSP maps) but also on the VLP parameters.

References

Filipova S, Cagan S, Dubrava J, Tysler M, Kneppo P, Rosik V. Diagnostic applications of body surface mapping in the clinical cardiology : The role of the norm definition for the correct using of the integral departure mapping. In Advances in Body Surface Mapping and High Resolution Electrocardiography. Yasui S, Abildskov JA, Yamada K, Harumi K, Editors. Life Medicom Co, Ltd, Nagoya, 1995, 109 – 122.

Filipova S. The follow-up study of departure isointegral body surface mapping in thrombolized and non-thrombolized patients with acute myocardial infarction. In Electrocardiology´96. From the Cell to the Body Surface. Liebman J, Editor. World Scientific Publ.Co, Singapore-New Yersey-London-Hong Kong, 1997, 497-500.                           

Hoekema R, Uijen GJH, van Oosterom A. On selecting a body surface mapping procedure. J. Electrocardiol., v. 32, 1999, č. 2, s. 93 – 101.  

Kozlikova K. Electric instability after myocardial infarction displayed in body surface potential maps. J Electrocardiol, 28 (4): 354-355, 1995.         

Kozlikova K, Hulin I, Murin J, Bulas J, Sapakova E, Bakosova M. Remodeling  in myocardial  infarction and body  surface potential maps. J Electrocardiol,  27(1): 29-33, 1994.                            

Tysler M, Rosik V, Turzova M. Practical system for BSP mapping studies. In Electrocardiology´98. (Preda I, Ed.). World Scientific, Singapore-New Yersey-London-Hong Kong, 1999, 81 – 84.