| Objective Aim to study the development of Transmural dispersion of repolarization(TDR) in ST-segment elevated myocardial infarction(STEMI) patients with or without successful revascularization by primary PCI; And probe the correlation between the decrease of TDR and various pertinent factors.Methods 341 consecutive patients with first-time ST-segment elevated myocardial infarction(STEMI) no longer than 12 hours after the presence of typical symptoms were enrolled in TianJin Chest Hospital between September 2006 and December 2009.341 STEMI patients were divided into revascularized group(n=212) and unrevascularized group(n=129) according to whether succeccful reperfusion were accomplished.36 healthy cases who has been excluded coronary heart disease were distributed into control group. Cases treated with successful primary PCI were divided into single-branch group(lack of more than 50%stenosis among non-IRAs, n=104) and multiple-branch group(at least 1 artery which presents stenosis>50% among non-IRAs, n=102).6 cases were not capable of being identified due to the presence of lesions approximate to 50%in non-IRA. IRAs of left anterior descending branch(LAD),left circumflex branch(LCX) and right coronary artery(RCA) were 51,17,36 in single-branch group, and 41,8,53 in multiple branch. Corrected Transmural dispersion of repolarization(TDRc):18-lead Digital ECG were recorded synchronously for each patient just pre-or post-PCI, and the ECG on the 2th,3th day were recorded as well. Tp-e interval was investigated in leads with limited ST-segment deviation before and after primary percutaneous coronary intervention (pPCI) in patients with ST-segment elevation myocardial infarction (STEMI). The T-end was defined as the junction of T wave and the isoelectric line. T-peak was identified the summit of upright T or the bottom of the inverted T wave. In order to eliminate the interference of heart rate, Corrected TDR (TDRc) was deployed in present study according to Bazett formula and TDRc was equal to the ratio of Tpeak-Tend/RR1/2. Parameters for cardiac function were detected, such as (1) Killip Classification.(2) Ultrasonic parameters included LVEDD, LVEF,IVS,LVPW. (3) Summit values of myocardial markers including CK-MB and TNI during the first 48 hours after the onset of AMI.(4) The Sum of STRs at all ST elevated leads of each patients post primary PCI was quantified as STR integral.(5) 129 cases with Lown stratification and SDNN in Holter of 129 cases during the first 7 days was recorded.And these 129 cases were divided into MVA group(n=57) or non-MVA group(n=72) according to Lown stratification. MVA was idertified with Lown=3 grade. Statistical analysis Statistical analysis was performed with SPSS software, version11.0. Continuous variables are reported as mean+SD. Categorical variables such as morbidity of Hypertension, Diabetes and hyperlipemia in Revascularized group or Un-revascularized group were compared using a x2 test or Fisher's exact test when appropriate. Comparisons of Tp-e/c value and Tp-e/c decrease were conducted using Student's t-test (unpaired, two-tailed) or one-way ANOVA.All variables were presented as median±standard deviation; Correlate analysis for multiple independent variables including (Age,Gender,CK-MB,TnI,and so on) and single dependent variable Tp-e/c decrease was performed with Partial correlate. A value of P<0.05 was considered statistically significant.Results Corrected TDR and arrhythmia in STEMI patients:Tp-e/c of Control and STEMI group:The Tp-e/c of STEMI group was 3.55±0.73, and the corresponding value of Control group was 2.28±0.33(P<0.01). Tp-e/c of non-Revascularized group at different timing points:The Tp-e/c of non-Revascularized group measured at admission, the 2th,3th day were 3.55±0.73,3.30±0.94 and 3.39±0.89. No significant difference was detectable among the 3 (P>0.05). It appeared to be a significant negative correlation between SDNN and TDRc(r=-0.258,P<0.05). Tp-e/c of MVA group was 4.45±1.24 in comparison with the 3.17±0.86 of non-MVA group(P<0.05).Development of TDRc in patients after successful primary PCI:Tp-e/c of both single-vessel group and multiple-vessel group were significantly reduced as compared with values measured pre-operation (P<0.01); There was no noted difference of Tp-e/c in multiple-vessel group at different time-points post-operation (P>0.05); In single-vessel group, no difference of Tp-e/c was detected in Tp-e/c measured at the first and second day (q>0.05), yet at the third day, Tp-e/c was decreased in comparison with the value measured at the second day (q<0.05), No significant decrease of Tp-e/c value and decrease percentage was detected in single or multiple-vessel group at different timing points post-operation (P> 0.05).Decrease of Tp-e/c for different IRA in Revascularized group was analyzed. No significant difference of Decrease of Tp-e/c for different IRAs such as LAD,LCX,RCA was detectable in either single-branch or multiple-branch group(P>0.05).Clinical Correlates of Tp-e/c decrease:Factors associated with Tp-e/c decrease are listed in Table 3. Clinical Correlates summarized from Patients with successful revascularization including age, gender, myocardial biological markers (CK-MB, troponinⅠ),ultrasonic parameters(LVEF, LVEDD, LVP,IVS), Killip Class, ST segment resolution(STR), whether presents Hypertension or Diabetes,and serious lesion in non-IRA vessel. Our study demonstrated STR recorded in infracted correlate leads is the exclusive influential factor on Tp-e/c decrease (r=0.3229, P＜0.0001)Conclusion TDR of STEMI cases are significantly elevated and sustained at a high-level during the first 3 days; The automatic nerve system may contribute to the enlargement of TDR of in STEMI patients.Primary PCI can effectively reduce the transmural dispersion of repolarization in STEMI patients no matter how serious the stenosis is in non-infarction related artery, recorded in infracted correlate leads is the exclusive influential factor on Tp-e/c decrease. this suggests that STR plays an crucial role in evaluation about the ventricular risk decrease after primary PCI. |
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