대한내과학회지 : 제 90 권제 1 호 2016 http://dx.doi.org/10.3904/kjm.2016.90.1.26 ST절상승급성심근경색증환자에서혈전흡인술에따른신호평균화심전도비교 대구파티마병원내과 이준영 최원석 정병천 이봉렬 강현재 김재희 강균은 Comparison of the Signal-averaged ECG after Primary Percutaneous Coronary Intervention according to Thrombus Aspiration in ST Elevation Myocardial Infarction Jun-Young Lee, Won Suk Choi, Byung-Chun Jung, Bong-Ryeol Lee, Hyun Jae Kang, Jae Hee Kim, and Gyoun-Eun Kang Department of Internal Medicine, Daegu Fatima Hospital, Daegu, Korea Background/Aims: Percutaneous coronary intervention (PCI) is the standard method of treating ST-segment elevation myocardial infarction (STEMI). There is continuing uncertainty as to whether reducing the thrombus burden through catheter aspiration improves the arrhythmogenic structure of the myocardium in STEMI. We compared the changes in electrical instability after thrombus aspiration-assisted primary PCI using conventional primary PCI. Methods: The study population included 170 consecutive patients with STEMI who underwent primary PCI. The patients were divided into 80 patients who underwent primary PCI only and 90 patients who underwent thrombus aspiration before PCI. The signal-averaged ECG (SAECG) was obtained 5 ± 2 days after the intervention. Results: There were no significant differences between the groups in terms of sex, age, cardiovascular risk factors, or time from the onset of symptoms to treatment. The duration of the low amplitude signals less than 40 μv (LAS40), duration of the QRS complex (QRSD), and root mean square voltage of the terminal 40 ms of the QRS complex (RMS40) did not differ between the thrombus aspiration and no thrombus aspiration groups. The incidences of QRSD > 114 ms and RMS40 < 20 μv were significantly lower in the thrombus aspiration group than the no thrombus aspiration group (19 vs. 8, p = 0.011 and 16 vs. 8, p = 0.047, respectively), while the incidence of LAS > 38 ms was significantly higher in the non-thrombus aspiration group (18 vs. 8, p = 0.018). Conclusions: Among random patients with STEMI, thrombus aspiration improved all of the parameters of SAECG, which is related to ventricular arrhythmogenesis, although the long-term clinical outcomes need to be assessed. (Korean J Med 2016;90:26-31) Keywords: Thrombectomy; Electrocardiography; Myocardial infarction Received: 2015. 7. 24 Revised: 2015. 9. 24 Accepted: 2015. 11. 5 Correspondence to Won Suk Choi, M.D. Department of Internal Medicine, Daegu Fatima Hospital, 99 Ayang-ro, Dong-gu, Daegu 41199, Korea Tel: +82-53-940-7455, Fax: +82-53-954-7417, E-mail: wons001@naver.com Copyright c 2016 The Korean Association of Internal Medicine This is an Open Access article distributed under the terms of the Creative Commons Attribution - 26 - Non-Commercial License (http://creativecommons.org/licenses/by-nc/3.0/) which permits unrestricted noncommercial use, distribution, and reproduction in any medium, provided the original work is properly cited.
- Jun-Young Lee, et al. SAECG after thrombus aspiration in STEMI - 서론 ST절상승급성심근경색증 (ST-segment elevation myocardial infarction, STEMI) 은관상동맥내불안정형죽상반이성장하면서파열되어, 그결과발생한혈전이혈류를차단하여전층허혈을일으키는질환을말한다. ST절상승급성심근경색증의치료에있어경피적관상동맥중재술 (percutaneous coronary intervention) 은현재까지가장효과적인치료방법으로알려져있다 [1,2]. 최근 ST절상승급성심근경색증환자에서사망률은 1995년부터 2010년까지 68% 가감소하였다. 이는일차적경피적관상동맥중재술이 11.9% 에서 60.8% 로크게상승하였고여러약물적치료들이알려졌으며, 환자들의위험인자들에서큰변화가있었기때문으로여겨진다. 하지만여전히 ST절상승급성심근경색증환자들에게서표준화된사망률은 4.4% 으로높다 [3]. ST절상승급성심근경색증환자의사망과관련된합병증으로심실성부정맥이있는데이런심실성부정맥이발생할경우사망률이 5배나증가한다 [4]. 심실성부정맥은심전도상 QT 간격최대값과최저값의차이 (QT dispersion) 의연장, 신호평균화심전도 (signal-averaged electrocardiography, SAECG) 상에서지연전위소견시발생빈도가높은것으로알려져있는데이는심실회복시간의비균일성이부정맥을일으키는주기전이기때문이다 [5]. 최근 ST절상승급성심근경색증환자에서일차적경피적관상동맥중재술을시행할경우혈전흡인술을같이시행하는경우가많은데이는혈전흡인술이혈관내혈전이일부가떨어져나가생길수있는원위부색전증의위험도를감소시키며미세혈관재관류를개선시킬수있기때문이다. 또한여러연구에서혈전흡인술이미세혈관재관류를개선시켜경피적관상동맥중재술후심근의전기생리학적불안정을줄여줄수있다는보고도있다 [6-8]. 이연구에서는 ST절상승급성심근경색증환자를대상으로일차적경피적관상동맥중재술을시행할때혈전흡인술이심근의전기생리학적불안정에어떤영향을주는지 SAECG 분석을통해알아보고자한다. 대상및방법 경피적관상동맥중재술시혈전흡인술을시행한 90명과혈전흡인술을시행하지않은 80명으로나누어퇴원전 SAECG를비교하였다. 시술후심전도상 atrial fibrillation, bundle branch block, hemiblock, intraventricular conduction defect가있는환자는연구에서제외하였다. ST절상승급성심근경색증의진단은 30분이상의전형적인흉통, 심전도에서인접한두개이상의분절에서 1 mm 이상의 ST 분절의지속적인상승과혈청검사에서 troponin-i가양성인경우를만족할때로정의하였다. Troponin I는 unicel dxl (Beckman Coulter, Brea, CA, USA) 을이용하여입원당시에측정하였고, troponin I의기준치는 0.1 ng/ml 로설정하였다. ProBNP 는 elecsys E170 (Roche Diagnostics, Mannheim, Germany) 을이용하여전기화학발광면역측정법 (electrochemiluminescence sandwich immunoassay) 으로증상발생 24시간이내에측정하였고, 측정범위는 5-35,000 pg/ml 이다. 관상동맥조영술은 aspirin 500 mg, clopidogrel 600 mg을복용후대퇴동맥혹은요골동맥을통해시행하였으며, 병변혈관의위치를나누어서분석하였다. 양군환자는모두응급실내원후 90분이내경피적관상동맥중재술을시행하였다. 혈전흡인술은관상동맥조영술후 aspiration catheter를병변근위부에위치시킨후 aspiration catheter를통하여혈전을흡인하였다. SAECG는퇴원전에시행하였으며 XYZ 유도로측정된표면심전도상 250 심박수를평균하여지연전위는 40 Hz high pass filter로여과하였고잡음은 0.7 μv 이하로하였다. 여과된 QRS군의기간 (duration of QRS complex, QRSD), 지연전위의에너지양 (root mean square voltage of terminal 40 ms of QRS complex, RMS40), 지연전위의기간 (duration of the low amplitude signals less than 40 μv, LAS40) 을통해양군간을비교하였다. SAECG 의양성소견은 QRSD가 114 ms 이상, LAS40 은 38 μv 이상그리고 RMS40 은 20 μv 이하인경우로정의하였다 [9]. 통계분석은 SPSS version 20 (SPSS Inc., Chicago, IL, USA) 을사용하여분석하였으며, 연속형변수는평균 ± 표준편차로, 범주형변수는빈도및백분율로나타내었다. 군간의비교는 unpaired t-test와 Chisquare test, Fisher s exact test로검증하였다. p value가 0.05 미만인경우통계학적으로유의하다고평가하였다. 2009년 8월부터 2013년 4월까지대구파티마병원에내원한 ST절상승급성심근경색증환자중일차적경피적관상동맥중재술을시행한 170명을대상으로하였다. 이는일차적 결 대상자의평균연령은혈전흡인술시행군에서 3 세정도 과 - 27 -
- 대한내과학회지 : 제 90 권제 1 호통권제 665 호 2016 - Table 1. Demographic and clinical findings of the study population Baseline characteristics PCI group (n = 80) PCI thrombus aspiration group (n = 90) p value Age, yr 61.8 ± 13.7 58.8 ± 12.5 0.134 Gender-Male, % 75 78 0.587 Hypertension 31 31 0.633 Diabetes mellitus 18 20 0.555 Hypercholesterolemia 14 17 0.845 Smoking 39 57 0.064 Family History 8 5 0.387 Previous MI 4 2 0.422 Previous HF 1 1 0.721 Previous CVA 0 1 0.529 Previous PVD 3 2 0.667 Values are presented as number or mean ± SD. PCI, percutaneous coronary intervention; MI, myocardial infarction; HF, heart failure; CVD, cerebrovascular accident; PVD, peripheral vascular disease. 낮았고성비에있어서는양군모두남자가많았으나통계상유의한차이는없었다 (75% vs. 78%, p = 0.587) (Table 1). 그외위험인자인고혈압, 당뇨병, 고지혈증, 가족력, 관상동맥질환의과거력등에서도두군간에통계적으로유의한차이는없었고, 기본혈액학적검사상에서도양군간차이가없었다 (Table 2). 그중흡연자는통계적유의성은없으나, 혈전흡인술시행군에서다소높은결과를보였다 (39 vs. 57, p = 0.064). Pro-BNP 는혈전흡인술미시행군에서다소높은결과를보였지만 (p = 0.058), 미시행군에서폐색병변이 left anterior descending artery (LAD) 인경우가많거나, left ventricular ejection fraction 이낮지는않았다. 관상동맥조영술상경색관련동맥이좌전하행지, 좌회선지인경우는혈전흡인술미시행군에서더높았다 (61.3% vs. 51.1%, p = 0.217 and 6.3% vs. 3.3%, p = 0.477). 우관상지인경우는혈전흡인술시행군에서높았으나, 세혈관모두통계상유의성은없었다 (32.5% vs. 45.6%, p = 0.087) (Table 2). Table 2. Baseline laboratory and coronary procedure results for the study population PCI group (n = 80) PCI thrombus aspiration group (n = 90) p value Symptom to Treatment, min 411.8 ± 351.1 411.3 ± 314.4 0.993 Stent implantation, n 78 82 0.446 Target lesion location, % Left anterior descending artery 49 (61.3) 46 (51.1) 0.217 Left circumflex artery 5 (6.3) 3 (3.3) 0.477 Right coronary artery 26 (32.5) 41 (45.6) 0.087 LVEF, % 48.6 47.5 0.478 Hemoglobin, mg/dl 13.8 ± 2.0 13.9 ± 1.8 0.566 BUN, mg/dl 14.3 ± 4.6 14.2 ± 4.8 0.221 LDL, mg/dl 113.0 ± 38.8 114.6 ± 38.7 0.785 TG, mg/dl 150.0 ± 90.7 143.4 ± 95.4 0.649 HDL, mg/dl 43.9 ± 11.6 45.0 ± 12.9 0.541 Pro BNP, mg/dl 917 ± 2,543.3 386.9 ± 661.4 0.058 Troponin I, mg/dl 21.0 ± 30.2 23.2 ± 32.8 0.663 CRP, mg/dl 0.8 ± 2.7 0.9 ± 2.7 0.873 Pre-procedure TIMI flow 0 48 (60) 60 (66.7) 0.426 Post-procedure TIMI flow 3 79 (98.8) 84 (93.3) 0.122 Stent diameter, mm 3.1 ± 0.4 3.3 ± 0.4 0.008 Stent length, mm 25.6 ± 5.9 25.9 ± 6.1 0.724 Values are presented as number (%) or mean ± SD. PCI, percutaneous coronary intervention; LVEF, left ventricular ejection fraction; LDL, low density lipoprotein; TG, triglyceride; HLD, High density lipoprotein; Pro-BNP, pro hormone brain natriuretic peptide; CRP, C-reactive protein; TIMI, thrombolysis in myocardial infarction. - 28 -
- 이준영외 6 인. 혈전흡인술에따른 SAECG 비교 - Table 3. Comparison of SAECG between the PCI and PCI plus thrombus aspiration groups PCI group (n = 80) PCI thrombus aspiration group (n = 90) p value QRSD, ms 104.6 ± 16.8 100.4 ± 13.8 0.076 RMS40, μv 42.5 ± 31.9 47.4 ± 30.6 0.308 LAS40, ms 29.0 ± 13.5 26.3 ± 10.8 0.150 QRSD 114 ms 19 (23.7) 8 (8.8) 0.011 RMS40 20 μv 16 (20) 8 (8.8) 0.047 LAS40 38 ms 18 (22.5) 8 (8.8) 0.018 SAECG 3 positive patients 9 (11.3) 3 (3.3) 0.069 Values are presented as number (%) or mean ± SD. SAECG, signal-averaged electrocardiography; PCI, percutaneous coronary intervention; QRSD, duration of QRS complex; RMS40, root mean square voltage of terminal 40 ms of QRS complex; LAS40, duration of the low amplitude signals less than 40 μv. 처음관상동맥조영술시 thrombolysis in myocardial infarction (TIMI) flow 등급 0을보이는경우는혈전흡인술시행군에서많았다 (60% vs. 66.7%, p = 0.426). 시술시사용한 stent diameter 는혈전흡인술미시행군에서 0.17 mm 정도작았고 (p = 0.008), length에서는양군간유의한차이를보이지않았다 (p = 0.724). 시술후 TIMI flow 등급 3을보이는경우는혈전흡인술미시행군에서다소많았으나통계적유의성은없었다 (98.8% vs. 93.3%, p = 0.122) (Table 2). QRSD의경우혈전흡인술미시행군에서길게나타났지만, 두군간의유의한차이는없었다 (104.6 ± 16.8 ms vs. 100.4 ± 13.8 ms, p = 0.076). RMS40의경우혈전흡인술시행군에서높게 (42.5 ± 31.9 μv vs. 47.4 ± 30.6 μv, p = 0.308) LAS40 는혈전흡인술시행군에서낮게측정되었으나 (29.0 ± 13.5 ms vs. 26.3 ± 10.8 ms, p = 0.150) 이역시유의한차이는보이지않았다. SAECG 의양성 parameter 를비교하였을때 QRSD 가 114 ms 이상, RMS40 가 20 μv 이하, LAS40 가 38 ms 이상나온경우모두혈전흡인술군에서적게나왔다 (19 vs. 8, p = 0.011, and 16 vs. 8, p = 0.047, and 18 vs. 8, p = 0.018). SAECG 상 3가지 parameter 가모두양성으로나온환자수는혈전흡인술시행군에서적게나왔으나통계적유의성은보이지않았다 (9 vs. 3, p = 0.069) (Table 3). 전체환자중심근경색이발생한동맥에따라 LAD 그룹과 non-lad 그룹으로나누어서 SAECG 분석을하였고 QRSD, RMS40, LAS40의유의한차이를보이지않았다 (102.2 ± 14.0 Table 4. Comparison of SAECG between the LAD and non-lad groups LAD group Non-LAD group p value QRSD, ms 102.2 ± 14.0 102.5 ± 16.5 0.919 RMS40, μv 46.1 ± 32.5 44.2 ± 30.2 0.685 LAS40, ms 28.4 ± 12.1 26.9 ± 12.3 0.434 Values are presented as mean ± SD. LAD, left anterior descending artery; QRSD, duration of QRS complex; RMS40, root mean square voltage of terminal 40 ms of QRS complex; LAS40, duration of the low amplitude signals less than 40 μv. vs. 102.5 ± 16.5, p = 0.919, and 46.1 ± 32.5 vs. 44.2 ± 30.2, p = 0.685 and 28.4 ± 12.1 vs. 26.9 ± 12.3, p = 0.434) (Table 4). 고 ST절상승급성심근경색증에서경색유발혈관의조기재관류는좌심실의기능을보존하고심근괴사를줄여생존율을향상시키는중요한치료법이다. ST절상승급성심근경색증치료에는혈전용해제투여, 경피적관상동맥중재술, 관상동맥우회술등이있다. 혈전용해제투여는 ST절상승급성심근경색증환자에서비교적쉽게사용할수있고경색혈관을재관류시켜급사의빈도를줄일수있다는장점이있으나 90분후경색혈관의재개통률이 60% 로비교적낮고뇌출혈등의합병증위험이있다. 경피적관상동맥중재술은이러한부작용을줄이고전문시술기관으로접근성을높여현재 ST절상승급성심근경색증환자의표준치료로인정받고있으며사망률을낮추는데가장크게기여하고있다 [10,11]. 하지만최근경피적관상동맥중재술은혈전이나파열된동맥경화반의잔여물질에의한원위부색전증의위험도가증가하고 slow/no reflow로인해경색부위가오히려증가할수있다는보고가있다 [12]. 이에대규모의 ST절상승급성심근경색증환자의재관류측면에서기존의경피적관상동맥중재술단독치료에혈전흡인술을추가하는치료가좋을수있다는연구가제시되었고 [13], 현재까지표준치료로서선택에는논란의소지가있지만여러연구들에서긍정적인면을보여주었다. Vlaar 등 [14] 의연구에서혈전흡인술그룹과전통적인경피적관상동맥중재술그룹을비교할때심장관련 1년사망률은혈전흡인술그룹에서 3.1% 낮았으며, 재협착률도혈전흡인술그룹에서 4.3% 낮았다. 주요심장사건도역시혈전흡인술그룹에서 찰 - 29 -
- The Korean Journal of Medicine: Vol. 90, No. 1, 2016-3.7% 낮아경피적관상동맥중재술전혈전흡인술은 ST절상승급성심근경색증환자에서 1년임상결과를상승시킨다고보고하였다. 또한국내연구에서는더나아가혈전흡인술을이용하여비교적큰혈전이나동맥경화반의잔여물을제거할수있지만크기가미세한혈전에는영향을주지못한것으로보이며차후이러한혈전들에의한원위부색전증을방지하기위하여혈전흡인술에추가적으로 glycoprotein IIb/IIIa 길항제를병행하여치료하였을때 index of microcirculatory resistance, microvascular obstruction가향상될수있음을보여주었다 [15]. 하지만최근한메타분석에서는혈전흡인술을했을때 stroke 빈도가늘어나는경향이있다는부정적인보고도있고 [16], 30일사망률비교에있어서경피적관상동맥중재술단독그룹과혈전흡인술을시행한그룹이유의한차이가없다는뒤바뀐보고도하고있다 [17]. 이처럼혈전흡인술에대한많은연구가진행되었지만사망률이아닌혈전흡인술과심실부정맥발생사이에연관관계를보여주는연구는많지않다. 과거 ST절상승급성심근경색증치료로혈전용해제를투여하였을때 QT dispersion이감소하고 SAECG 상지연전위발생빈도를줄임으로써심실성부정맥의발생을줄여주는것으로알려져있다. 이는경색부위의재관류상태와관련이있고, 개폐여부가심근의전기생리학적안정 (electrical stabilities) 에중요한역할을한것으로판단된다 [18,19]. 최근혈전흡인술또한혈전이나파열된동맥경화반의잔여물질에의한원위부색전을개존시켜심근의전기생리학적안정성을높일수있다고생각되는데, 일부연구에서혈전흡인술이혈관내 thrombus burden을줄여심실재분극의다양성을줄이고 QT dispersion을감소시킴으로써심실성부정맥발생감소에영향을미칠수있음을보여주었다 [20]. 이연구에서는 ST절상승급성심근경색증환자에있어서혈전흡인술이심근의전기생리학적불안정성을향상시켜주는지 SAECG상지연전위분석을통해알아보고자하였다. 연구에서혈전흡인술을시행한군과하지않은군에서평균연령, 성비등의기본특성상유의한차이는없었다. 또한위험인자, 기본혈액학적검사에서도통계차이를보이지않아양군간기본특성이동등한조건에서연구가시행되었다고할수있다. SAECG 분석에서통계적유의성은없었지만혈전흡인술시행군에서 QRSD (ms) 의경우작아지는결과를보였다 (p = 0.076). 또한 QRSD가 114 ms 이상나온경우는혈전흡인술을시행한군에서통계적으로유의하게적었으며 (19 vs. 8, p = 0.011), RMS40가 20 μv 이하인경우도혈전흡인술시행군에서적었다 (16 vs. 8, p = 0.047). 또한 LAS40가 38 ms 이상인경우도혈전흡인술시행군에서통계적으로유의하게적어 (18 vs. 8, p = 0.018), 혈전흡인술군에서 SAECG상지연전위양성소견이통계적으로유의하게적게나타난다는것을알수있었다. 결국혈전흡인술이 SAECG상의지연전위와관련된 parameter 의호전을보이게하여심실부정맥을줄이는데기여할수있을것으로생각된다. 이연구는단일기관에서진행되었으며대상환자의수가적다는한계가있다. 또한경피적관상동맥중재술시행환자들에대한추적관찰이없어 SAECG 분석이외의추가적으로생존율과주요심장사건에대한직접적인비교를할수없었다. 이에앞으로더많은급성심근경색증환자를대상으로한전통적인경피적관상동맥중재술과추가적혈전흡인술을시행하는것을비교하는전향적연구가필요할것으로생각된다. 요약목적 : ST절상승급성심근경색에서경피적관상동맥중재술이표준치료로시행된다. 혈전흡인술이혈전찌거기 (thrombus burden) 를줄임으로써 ST절상승급성심근경색증환자의심실부정맥발생을줄일수있을지에대한여러연구가진행되어왔다. 이연구는 ST절상승급성심근경색증환자에서전통적인경피적관상동맥중재술그룹과비교할때혈전흡인술을시행한그룹에서심근의전기학적불안정성을향상시킬수있는가를 SAECG 분석을통해밝히고자하였다. 방법 : 연구대상은 ST절상승급성심근경색증에서경피적관상동맥중재술을시행한 170명을대상으로하였다. 환자는두군으로나누어서 80명은전통적인경피적관상동맥중재술만시행하였고 90명은경피적관상동맥중재술시행전혈전흡인술을시행하였다. SAECG 는시술후 5 ± 2일날시행하였다. 시술후심전도상 atrial fibrillation, bundle branch block, hemiblock, intraventricular conduction defect 가있는군은 SAECG 분석에서제외하였다. 결과 : 급성심근경색증환자에서양군간기본특성상에는특별한차이가없었다. SAECG 분석에서 QRSD (ms) 의경우미시행군에서 4 ms 길게나왔고, RMS40 의경우 5 μv 높게측정되었고, LAS40 의경우시행군에서 3 μv 높게측정되었다. 이는통계적유의성을보여주지는못하였지만, SAECG 양성소견을비교하였을때 QRSD가 114 ms 이상, RMS40 이 - 30 -
- Jun-Young Lee, et al. SAECG after thrombus aspiration in STEMI - 20 μv 이하인경우는혈전흡인술군에서모두적게나왔으며 (19 [23.7%] vs. 8 [8.8%], p = 0.011, and 16 [20%] vs. 8 [8.8%], p = 0.047). LAS40가 38 ms 이상으로나온경우도혈전흡인술군에서적었다 (18 [22.5%] vs. 8 [8.8%], p = 0.018). 결론 : STEMI 환자에서혈전흡인술은 SAECG 상에서심실부정맥발생과관련된임상지표들을향상시키는결과를보여주었다. 앞으로이에대한장기적인임상연구결과가추가적으로필요하다. 중심단어 : 혈전흡인 ; 심전도 ; 심근경색증술 REFERENCES 1. Keeley EC, Boura JA, Grines CL. Primary angioplasty versus intravenous thrombolytic therapy for acute myocardial infarction: a quantitative review of 23 randomised trials. Lancet 2003;361:13-20. 2. Boersma E; Primary Coronary Angioplasty vs. Thrombolysis Group. Does time matter? A pooled analysis of randomized clinical trials comparing primary percutaneous coronary intervention and in-hospital fibrinolysis in acute myocardial infarction patients. Eur Heart J 2006;27:779-788. 3. Puymirat E, Simon T, Steg PG, et al. Association of changes in clinical characteristics and management with improvement in survival among patients with ST- elevation myocardial infarction. JAMA 2012;308:998-1006. 4. Marchioli R, Barzi F, Bomba E, et al. Early protection against sudden death by n-3 polyunsaturated fatty acids after myocardial infarction: time-course analysis of the results of the Gruppo Italiano per lo Studio della Sopravvivenza nell Infarto Miocardico (GISSI)-Prevenzione. Circulation 2002;105:1897-1903. 5. Lim DS, Kim YH, Lee SC, et al. Relation between QT dispersion and late potential in acute myocardial infarction. Korean Circ J 1996;26:442-448. 6. Ali A, Malik FS, Dinshaw H, et al. Reduction in QT dispersion with rheolytic thrombectomy in acute myocardial infarction: evidence of electrical stability with reperfusion therapy. Catheter Cardiovasc Interv 2001;52:56-58. 7. Bavry AA, Kumbhani DJ, Bhatt DL. Role of adjunctive thrombectomy and embolic protection devices in acute myocardial infarction: a comprehensive meta-analysis of randomized trials. Eur Heart J 2008;29:2989-3001. 8. Sardella G, Mancone M, Bucciarelli-Ducci C, et al. Thrombus aspiration during primary percutaneous coronary intervention improves myocardial reperfusion and reduces infarct size: the EXPIRA (thrombectomy with export catheter in infarct-related artery during primary percutaneous coronary intervention) prospective, randomized trial. J Am Coll Cardiol 2009;53:309-315. 9. Cain ME, Anderson JL, Arnsdore MF, Mason JW, Scheinman MM, Waldo AL. Signal-averaged electrocardiography. J Am Coll Cardiol 1996;27:238-249. 10. Weaver WD, Simes RJ, Betriu A, et al. Comparision of primary coronary angioplasty and intravenous thrombolytic therapy for acute myocardial infarction. JAMA 1997;278: 2093-2098. 11. Lee JH, Jeong MH, Rhee J, et al. Factors influencing delay in symptom-to-door time in patients with acute ST-segment elevation myocardial infarction. Korean J Med 2014;87: 429-438. 12. Kotani J, Nanto S, Mintz GS, et al. Plaque gruel of atheromatous coronary lesion may contribute to the no-reflow phenomenon in patients with acute coronary syndrome. Circulation 2002;106:1672-1677. 13. Svilaas T, Vlaar PJ, van der Horst IC, et al. Thrombus aspiration during primary percutaneous coronary intervention. N Engl J Med 2008;358:557-567. 14. Vlaar PJ, Svilaas T, van der Horst IC, et al. Cardiac death and reinfarction after 1 year in the thrombus aspiration during percutaneous coronary intervention in acute myocardial infarction study (TAPAS): a 1-year follow-up study. Lancet 2008;371:1915-1920. 15. Ahn SG, Lee SH, Lee JH, et al. Efficacy of combination treatment with intracoronary abciximab and aspiration thrombus aspiration on myocardial perfusion in patients with ST-segment elevation myocardial infarction undergoing primary coronary stenting. Yonsei Med J 2014;55:606-616. 16. De Luca G, Navarese EP, Suryapranata H. A meta-analytic overview of thrombectomy during primary angioplasty. Int J Cardiol 2013;166:606-612. 17. Fröbert O, Lagerqvist B, Olivecrona GK, et al. Thrombus aspiration during ST-segment elevation myocardial infarction. N Engl J Med 2013;369:1587-1597. 18. Perkiömäki JS, Koistinen MJ, Yli-Mäyry S, Huikuri HV. Dispersion of QT interval in patients with and without susceptibility to ventricular tachyarrhythmias after previous myocardial infarction. J Am Coll Cardiol 1995;26:174-179. 19. Gomes JA, Winters SL, Stewart D, Horowitz S, Milner M, Barreca P. A new noninvasive index to predict sustained ventricular tachycardia and sudden death in the first year after myocardial infarction: based on signal-averaged electrocardiogram, radionuclide ejection fraction holter monitoring. J Am Coll Cardiol 1987;10:349-357. 20. Ilkay E, Yavuzkir M, Karaca I, Akbulut M, Pekdemir M, Aslan N. The effect of ST resolution on QT dispersion after interventional treatment in acute myocardial infarction. Clin Cardiol 2004;27:159-162. - 31 -