心肌型脂肪酸结合蛋白对心外科围术期心肌缺血与损伤的预测价值

目的 通过观察冠状动脉旁路移植术和室间隔缺损修补术围手术期不同时间人类心肌型脂肪酸结合蛋白(h-FABP)的动态变化,评价h-FABP在术中对心肌缺血及损伤的预测作用.方法 随机选取2008年2月至12月行冠状动脉旁路移植术和室间隔缺损修补术者各30例,分别于术前、主动脉夹闭时及主动脉开放后10 min、2 h.6 h、12 h、24 h取静脉血,检测h-FABP、缺血修饰白蛋白(IMA)、心肌肌钙蛋白I(cTnI)和肌酸激酶同工酶(CK-MB)的含量.结果 h-FABP与IMA变化趋势一致.h-FABP与cTnI和CK-MB变化趋势相似,但是h-FABP在心肌缺血与损伤后血中高峰时间出现得更早,维持时间较短,在2 h后即明显下降,24 h回复基线水平.经线性相关分析,冠状动脉旁路移植术组h-FABP的峰值与IMA、CK-MB和cTnI的峰值高度呈正相关(P<0.05),相关系数r分别为0.948、0.964和0.961.室间隔缺损修补术组有类似的结果,h-FABP的峰值与IMA、CK-MB和cTnI的峰值高度呈正相关(P<0.01),相关系数r分别为0.986、0.978和0.957.结论 h-FABP是心外科围手术期心肌缺血和损伤的早期诊断指标.h-FABP血中水平的定量监测可以有效地预测术中心肌缺血与损伤情况.     

心肌型脂肪酸结合蛋白对心外科围术期心肌缺血与损伤的预测价值

目的 通过观察冠状动脉旁路移植术和室间隔缺损修补术围手术期不同时间人类心肌型脂肪酸结合蛋白(h-FABP)的动态变化,评价h-FABP在术中对心肌缺血及损伤的预测作用.方法 随机选取2008年2月至12月行冠状动脉旁路移植术和室间隔缺损修补术者各30例,分别于术前、主动脉夹闭时及主动脉开放后10 min、2 h.6 h、12 h、24 h取静脉血,检测h-FABP、缺血修饰白蛋白(IMA)、心肌肌钙蛋白I(cTnI)和肌酸激酶同工酶(CK-MB)的含量.结果 h-FABP与IMA变化趋势一致.h-FABP与cTnI和CK-MB变化趋势相似,但是h-FABP在心肌缺血与损伤后血中高峰时间出现得更早,维持时间较短,在2 h后即明显下降,24 h回复基线水平.经线性相关分析,冠状动脉旁路移植术组h-FABP的峰值与IMA、CK-MB和cTnI的峰值高度呈正相关(P<0.05),相关系数r分别为0.948、0.964和0.961.室间隔缺损修补术组有类似的结果,h-FABP的峰值与IMA、CK-MB和cTnI的峰值高度呈正相关(P<0.01),相关系数r分别为0.986、0.978和0.957.结论 h-FABP是心外科围手术期心肌缺血和损伤的早期诊断指标.h-FABP血中水平的定量监测可以有效地预测术中心肌缺血与损伤情况.     

心脏型脂肪酸结合蛋白在停跳与不停跳冠状动脉旁路移植术围术期变化的研究

目的研究心脏型脂肪酸结合蛋白(H-FABP)及肌钙蛋白I(cTnI)等在体外循环及非体外循环冠状动脉旁路移植术中与心肌损伤的关系。方法将冠状动脉旁路移植术的55例患者随机分为体外循环组25例和非体外循环组30例,肝素化前,体外循环组在主动脉开放后1、2、4、8、24、48和72h,非体外循环组在最后1支血管远心端吻合后相同时间点采血10ml,检测H-FABP、cTnI及肌酸激酶同工酶(CK-MB)等,并记录临床指标变化。结果与非体外循环组比较,体外循环组总H-FABP[(95.42±60.48)μg/L vs(3.91±1.46)μg/L,P=0.000]水平显著升高,且H-FABP在术后1h及达顶峰值,早于cTnI及CK-MB。结论非体外循环冠状动脉旁路移植术式心肌损伤程度较体外循环术式小;围术期H-FABP检测有助于围术期心肌损伤的早期诊断。     

非体外循环冠状动脉旁路移植术围手术期CK-MB、cTnI的变化

分别测定不同时点体外循环下冠状动脉旁路移植术（CABG）和非体外循环下冠状动脉旁路移植术（OPCAB）患者肌酸磷酸激酶同工酶（CK-MB）、心肌肌钙蛋白（cTnI）的平均血浆浓度的变化。结果心肌再灌注6h及再灌注24h，CABG组患者CK-MB、cTnI血浆浓度较OPCAB患者明显增高。认为CABG对心肌的损伤程度较OPCAB严重，OPCAB有较好的心肌保护作用。     

非体外循环和体外循环冠状动脉旁路移植术的对比研究

96例冠状动脉旁路移植术(CABG)患者,按照术式的不同分为非体外循环冠状动脉旁路移植术(OPCAB)组46例和常规体外循环冠状动脉旁路移植术(CCABG)组50例.两组患者均于术前1 d及术后4 h、24 h、72 h、5 d、7 d空腹采集静脉血,检测血清cTnI、CK-MB及血脂水平;观察并比较两组患者术后呼吸机辅助时间和围手术期并发症发生率以及ICU停留时间、术后住院时间.发现术后4、24 h,CCABG组cTnI和CK-MB水平均明显高于OPCAB组;术后72 h,两组cTnI水平亦有明显差异;两组术后血脂水平无明显差异.提示OPCAB对心肌的损伤程度低于CCABG;OPCAB可减少呼吸机辅助时间、ICU停留时间、住院时间,可降低肾功能不全、呼吸功能不全的发生率.     

非体外循环冠状动脉旁路移植术围术期肌钙蛋白(TnI)及磷酸激酸(CK-MB)变化的研究

目的近年来随着心脏外科手术器械的发展、外科手术技艺的不断提高,微创心脏外科已逐渐成为心脏外科领域的一大特点。由此,迫使麻醉医师去迎接新的挑战,不断探索新的麻醉方法、新的心肌保护方法。本研究初步观察非体外循环冠状动脉旁路移植术(off-pump CABG)围术期肌钙蛋白I(TnI)及磷酸激酸(CK-MB)的变化,探讨TnI及CK-MB在评价心肌损伤和心肌保护效果的临床价值。方法30例行off-pump CABG病人,分别在麻醉诱导后、开放主动脉侧壁钳后5 min、6 h、24 h及48 h采集深静脉血,测定血浆TnI、CK-MB浓度;并仔细观察记录围术期心肌缺血及其它并发症的发生情况。结果30例病人麻醉诱导后血浆TnI、CK-MB水平分别为(0．98±1．5)ng／ml、(4．5±4．4)ng／ml,开放主动脉侧壁钳后5 min(6．39±5．3、13．37±7．90)、6 h(14．39±9．4、24．54±13．9)、24 h(14．34±8．3、20．09±16．9)、48 h(8．89±8．4、10．22±8．2)血浆TnI、CK-MB均较麻醉诱导后显著升高(P<0．05)。TnI、CK-MB的峰值浓度与冠状动脉旁路桥的远端吻合时间无明显正相关。结论非体外循环冠状动脉旁路移植术术中及术后血浆TnI、CK-MB均明显升高,提示有心肌损伤; TnI、CK-MB的峰值浓度与冠状动脉旁路桥的远端吻合时间无明显正相关,提示off-pump CABG心肌损伤的程度不仅仅与心脏操做有关,还可能与其技术本身的缺陷、麻醉方法等有关。     

含左旋精氨酸的心肌保护液对冠状动脉旁路移植术中氧摄取量的影响

目的:了解含左旋精氨酸(L-Arg)的心肌保护液对冠状动脉旁路移植术中心肌氧摄取率的影响。方法:20例患者随机分为2组,每组10例。对照组:常规心肌保护液组,不添加L-Arg。实验组:每1 000 mL改良托马斯液中加入7.5 g L-Arg。记录2组患者阻断主动脉前(T1)、主动脉开放后5min(T2)、主动脉开放后20 min(T3)桡动脉(A)和冠状静脉窦(CS)回流血中氧分压、血氧饱和度,计算心肌氧摄取率,记录术后12 h(T4)、术后24 h(T5)、术后48 h(T6)心肌酶CK-MB和cTnI指标。结果:20例患者无手术死亡,均痊愈出院。实验组氧摄取率高于对照组。结论:添加一定浓度L-Arg能够提高心肌保护液在冠状动脉旁路移植术中心肌保护效果。     

心肌肌钙蛋白I对体外循环心内直视手术心肌损伤的判定价值

目的探讨心肌肌钙蛋白I（cTnI）对体外循环心内直视手术心肌损伤的判定价值。方法40例心脏瓣膜置换手术病人随机分为两组，冷晶体停跳液组（A组），温血停跳液组（B组），每组20例，分别于围手术期多时点采取中心静脉血，测定血清cTnI、心肌肌酸激酶（CK）及其心肌肌酸激酶同工酶（CK-MB）。结果术前两组的cTnI、CK及CK-MB水平均在正常范围，开放主动脉后1h至术后24h达峰值．其后缓慢下降。术后24h、48hB组cTnI水平明显低于A组（P〈0．05），CK—MB在开放主动脉后1hB组低于A组。cTnI峰值浓度与主动脉阻断时间呈直线正相关。结论cTnI判定心内直视手术围手术期心肌损伤的敏感性及特异性明显优于CK、CK—MB，对围手术期心肌缺血损伤的诊断、预后及心肌保护效果的评价具有重要的临床价值。     

乌司他丁在婴幼儿体外循环手术期间的心肌保护作用

目的探讨乌司他丁在婴幼儿体外循环手术中对心肌缺血/再灌注损伤的保护作用。方法选择38例诊断为室间隔缺损的婴幼儿患者,随机分为试验组(n=18):1.2万U/kg乌司他丁;对照组(n=20):以等量生理盐水代替。记录阻断和转流时间,血管活性药物使用和心脏复跳情况。于转流前,主动脉开放即刻,开放30min,停机后4h、24h检测CK、CK-MB和cTnI,并观察心肌超微结构。结果①两组CK-MB、CK和cTnI转流前差异均无统计学意义,CPB后明显升高(P<0.05);试验组停机后4h、24h,CK、CK-MB较对照组低(P<0.05),cTnI主动脉开放30min,停机后4h、24h低于对照组(P<0.05)。②实验组多巴胺/多巴酚丁胺平均使用剂量少于对照组(P<0.05),心脏自动复跳率明显高于对照组(P<0.01),术后心肌组织超微结构显示心肌细胞损害较对照组轻。结论乌司他丁能降低CK、CK-MB、cTnI的释放,减轻婴幼儿体外循环手术中心肌损害,对心肌缺血/再灌注损伤有保护作用。     

体外与非体外循环冠状动脉旁路移植术后血清miR-1、miR-133a、miR-208a水平变化及分析

目的探究行体外循环冠状动脉旁路移植术(ONCABG)与非体外循环冠状动脉旁路移植术(OPCABG)患者术后血清miR-1、miR-133a、miR-208a水平变化。方法选取2016年2月—2019年2月本院多支冠状动脉病变需要行CABG的患者94例。根据手术方式,将94例患者分为ONCABG组47例和OPCABG组47例。利用荧光实时定量PCR法检测所有患者术前、术后不同时间血清miR-1、miR-133a、miR-208a水平。采用化学发光免疫分析仪检测所有患者术前、术后不同时间血清心肌肌钙蛋白I(cTnI)、肌酸激酶同工酶(CK-MB)水平。分析血清miR-1、miR-133a、miR-208a水平与cTnI、CK-MB水平的相关性。结果与术前相比,两组患者术后4 h、24 h血清miR-1、miR-133a、miR-208a、cTnI、CK-MB水平升高(P0.05)。与术后4 h相比,两组患者术后24 h血清miR-1、miR-133a、miR-208a、cTnI、CK-MB水平降低(P0.05)。与ONCABG组相比,OPCABG组术后4 h、术后24 h血清miR-1、miR-133a、miR-208a、cTnI、CK-MB水平降低(P0.05)。Pearson分析显示,两组患者术后4 h、术后24 h血清miR-1、miR-133a、miR-208a水平与cTnI、CK-MB水平均呈正相关(P0.05)。结论 miR-1、miR-133a、miR-208a有望作为判断ONCABG与OPCABG后心肌损伤的重要生物标志物。本研究为ONCABG与OPCABG在临床上的选择提供了一定的参考依据。     

心肌肌钙蛋白I测定对判定体外循环心内直视手术心肌损伤的价值

目的探讨心肌肌钙蛋白I(cTnI)的测定对体外循环心内直视手术心肌损伤的判定价值。方法40例心脏瓣膜置换手术患者随机分为两组,冷晶体停跳液组(A组),温血停跳液组(B组),每组20例,分别于围术期多时点采取中心静脉血,测定血清cTnl、CK及CK—MB的水平。结果术前两组患者的cTnI、CK及CK—MB水平均在正常范围,开放主动脉后1h至术后24h达峰值,其后缓慢下降。术后24h、48h B组cTnI水平明显低于A组(P＜0．05)。CK—MB在开放主动脉后1hB组低于A组(P＜0．05)。cTnI峰值浓度与主动脉阻时间呈直线正相关(P＜0．05)。结论cTnI判定心内直视手术围术期心肌损伤的敏感性及特异性明显优于CK、CK—MB,对围术期心肌缺血损伤的诊断、预后及心肌保护效果的评价具有重要的临床价值。     

Comparison of Cardiac Troponin I versus T and Creatine Kinase MB after Coronary Artery Bypass Grafting in Patients with and without Perioperative Myocardial Infarction

BACKGROUND AND PURPOSE: Cardiac troponins have shown to be specific markers of myocardial injury. The aim of this prospective study was to compare patterns and kinetics of troponin I and T after coronary artery bypass grafting (CABG) with or without perioperative myocardial infarction (PMI). PATIENTS AND METHODS: 119 patients (male/female: 96/23, age 64 +/- 10 years) underwent first time elective CABG. Preoperative mean ejection fraction was 55.8% +/- 15.6%. The mean number of grafts was 3.1 +/- 1.1/patient, in 85.7% the internal mammary artery was used. Cardiac troponin I (cTnI) and T (cTnT) levels, total serum activities of creatine kinase (CK) and creatine kinase isoenzyme MB (CK-MB) were measured before operation, at arrival on the intensive care unit (ICU), and 6, 12, 24, 48, and 120 h after unclamping of the aorta. Twelve lead electrocardiograms (ECGs) were recorded preoperatively and at days 1, 2, and 5. Perioperative data and postoperative cTnI and cTnT levels were correlated statistically. RESULTS: Two patients died due to refractory myocardial failure in the early postoperative period. For further evaluation, patients were divided in two groups according to postoperative ECG changes (group I: patients without PMI, n = 107; group II: patients with PMI, n = 10: six of them with Q-wave and four of them with non-Q-wave PMI). Calculated best cutoff values for cTnI and cTnT were 8.35 microg/l and 0.768 microg/l in ROC (receiver-operator characteristic) analysis. Serum concentrations of cTnI, and cTnT were in the normal range preoperatively and increased significantly after surgery in both groups. In both groups, cTnI reached its medium peak level after 24 h (group I: 2.7 microg/l, 95% confidence interval [CI]: [2.1,3.2]); group II: 70.5 microg/l). CTnT reached its medium peak level in group I without PMI after 48 h (0.298 microg/l, 95% CI: [0.254,0.354]), in group II with PMI not until 120 h (3.0 microg/l) postoperatively. In group II serum level of both troponins remained considerably high at 120 h (cTnI median = 10.75 microg/l, cTnT median = 3 microg/l). CONCLUSION: Release patterns of cTnI and cTnT after CABG are different: cTnI reaches its postoperative peak value earlier and declines more quickly than cTnT. After uncomplicated CABG, serum levels of both cardiac troponins remain continuously low. Elevated concentrations reflect perioperative myocardial ischemia or infarction. CTnT shows a different release pattern in patients with or without myocardial infarction.     

Vulnerability of paediatric myocardium to cardiac surgery.

OBJECTIVE: Myocardial injury is an important cause of mortality and morbidity after paediatric cardiac surgery. Data obtained from studies in animals imply that juvenile myocardium is more resistant to the effects of ischaemia and reperfusion than adult myocardium but there is little confirmatory evidence in the clinical setting. DESIGN: Prospective observational study of biochemical markers of myocardial injury in a paediatric population undergoing cardiac surgery. SETTING: Tertiary referral centre for paediatric cardiac surgery. PATIENTS: Forty patients undergoing paediatric cardiac surgery of varying complexity including closure of atrial and ventricular septal defects and arterial switch for simple transposition. A control group included patients undergoing thoracotomy for closure of a patent ductus arteriosus or repair of a coarctation. INTERVENTIONS: Serial measurements of myoglobin, the MB isoenzyme of creatine kinase (CK-MB), and the highly specific markers of myocardial damage cardiac troponin T (cTnT) and I (cTnI) were made before and 1, 6, 24, and 48 to 72 hours after operation. RESULTS: There were significant increases in myoglobin and CK-MB, but not cTnT or cTnI, in the control group. There were significant increases in the four biochemical markers in all the cardiac operations but especially in the ventricular septal defect and transposition group. Increases in CK-MB and cTnT were about five times greater than those previously reported in adult patients. CONCLUSIONS: (i) Cardiac troponins are more specific markers of myocardial injury in paediatric cardiac surgery than myoglobin and CK-MB. (ii) Paediatric myocardium seems to be more vulnerable to injury during cardiac surgery than adult myocardium.     

急性冠状动脉综合征血清缺血修饰白蛋白的动态变化

目的:探讨血清缺血修饰白蛋白(IMA)对急性冠状动脉综合征早期的诊断价值。方法:将56例急性冠状动脉综合征患者分为三组,不稳定性心绞痛组(n=25),ST抬高心肌梗死组(n=20),非ST抬高心肌梗死组(n=11),另选50例健康体检者为正常对照组。分别于胸痛发作2、4、6、12及24 h抽血检测56例急性冠状动脉综合征患者的血清缺血修饰白蛋白、肌钙蛋白Ⅰ(cTnI)、肌酸激酶MB同工酶(CK-MB),分析缺血修饰白蛋白对急性冠状动脉综合征的诊断价值。结果:在急性冠状动脉综合征患者中缺血修饰白蛋白水平于胸痛发作2小时已明显增高并达高峰,4小时仍持续增高,明显高于正常对照组(P<0．01),6小时降至正常。而CK-MB、cTnI水平在胸痛发作4小时开始增高,6小时明显增高,以后逐步递增并在24小时达高峰。不稳定型心绞痛、ST抬高的心肌梗死、非ST抬高的心肌梗死三组中,缺血修饰白蛋白水平升高以不稳定型心绞痛组最明显。结论:缺血修饰白蛋白是诊断急性冠状动脉综合征的早期敏感指标,是目前唯一的诊断心肌缺血的生化标志物。     

Diagnostic discrimination between graft-related and non-graft-related perioperative myocardial infarction with cardiac troponin I after coronary artery bypass surgery.

AIMS: The rise of markers for myocardial injury indicates early graft-related or non-graft-related perioperative myocardial infarction (PMI) after coronary artery bypass grafting (CABG). A diagnostic discrimination between these two situations may enable adequate therapeutic measures, limiting myocardial damage, and improving outcome. METHODS AND RESULTS: In a prospective study, 94 among 3308 consecutive CABG patients underwent acute reangiography because of evidence of PMI. Of these 94 patients, 56 had graft-related PMI (group 1), 38 patients had non-graft-related PMI (group 2), and 95 patients without evidence of PMI and angiographically patent grafts served as control (group 3). Cardiac troponin I (cTnI), creatine kinase (CK), and its MB fraction were determined. CTnI, but not CK/CK-MB levels were significantly higher in group 1 than in groups 2 and 3 at 12 and 24 h after aortic unclamping (P<0.0001). Receiver operating characteristic and multivariable logistic regression analyses indicated cTnI as the best discriminator between PMI 'in general' and 'inherent' release of cTnI after CABG with a cut-off value of 10.5 ng/mL and between graft-related and non-graft-related PMI with a cut-off value of 35.5 ng/mL. CONCLUSION: Perioperative cTnI elevation after CABG separates among patients with graft-related, non-graft-related, and without PMI, however, not earlier than 12 h after surgery.     

A proposed strategy for utilization of creatine kinase-MB and troponin I in the evaluation of acute chest pain

In recent years, cardiac troponins have attracted great interest as a marker for myocardial injury. However, there are limited data on strategies for use of creatine kinase (CK)-MB and troponin I (cTnI) in clinical practice. We sought to develop a testing strategy using prospectively collected clinical data including serial CK-MB and cTnI levels from 1,051 patients aged > or = 30 years admitted to a teaching hospital for acute chest pain. Diagnostic performance was evaluated for peak values of CK-MB and cTnI obtained during the first 24 hours for the combined end point of acute myocardial infarction and/or major cardiac events within 72 hours. The overall diagnostic accuracy was similar for both cardiac markers alone, and for the combination of cTnI and CK-MB (receiver-operating characteristic curve 0.84, 0.86, and 0.87, respectively). In the multivariate analysis, models including cardiac markers showed that both CK-MB and cTnI added information to clinical data to predict the combined end point, but cTnI added significantly less. Using recursive partitioning analysis, we developed a strategy that would restrict routine cTnI use to patients with normal CK-MB results and findings on the electrocardiogram consistent with ischemia. This strategy would divide patients with suspected myocardial ischemia into 4 groups with risks for the combined end point of 4%, 13%, 26%, and 85%. Thus, cTnI adds information to CK-MB mass and clinical data for predicting major cardiac events, but this contribution is mainly in patients with evidence of myocardial ischemia on their electrocardiograms.     

Cardiac troponin I for stratification of early outcomes and the efficacy of enoxaparin in unstable angina: a TIMI-11B substudy

OBJECTIVES: We sought to evaluate cardiac troponin I (cTnI) for predicting early clinical outcomes and the efficacy of enoxaparin among patients with non-ST segment elevation acute coronary syndrome (ACS) and negative creatine kinase, MB fraction (CK-MB) levels. BACKGROUND: Cardiac TnI identifies patients with unstable angina who are at higher risk of death or myocardial infarction (MI) by 30 days. The utility of cTnI for predicting very early clinical events, including recurrent ischemia, and the efficacy of enoxaparin are not yet established. METHODS: At baseline and 12 h to 24 h after enrollment in the Thrombolysis in Myocardial Infarction (TIMI)-11B trial, samples were collected for cTnI determination. RESULTS: Among 359 patients with negative serial CK-MB values, 50.1% had a cTnI result > or =0.1 ng/ml within the first 24 h. Patients with elevated cTnI were at higher risk of death or MI at 48 h (3.9 vs. 0%, p = 0.01) and 14 days (13.9 vs. 2.2%, p<0.0001). Elevated cTnI also correlated with higher risk of recurrent ischemia requiring urgent revascularization by 48 h (10.0 vs. 1.7%, p = 0.001) and 14 days (20.6 vs. 5.6%, p< or =0.0001). Enoxaparin had a greater benefit among patients with elevated vs. normal cTnI (p = 0.03), achieving a 47% reduction in the risk of death, MI or urgent revascularization by 14 days in cTnI-positive patients (p = 0.007). CONCLUSIONS: Elevation of cTnI among patients with non-ST segment elevation ACS and negative levels of CK-MB identifies those at higher risk for very early adverse outcomes, including severe recurrent ischemia. Treatment with enoxaparin reduces the risk associated with elevated cTnI.     

Temporal pattern of cardiac troponin I after thoracotomy and lung surgery

BACKGROUND: Several studies have shown that patients with perioperative myocardial infarction (MI) are at higher risk for subsequent cardiac events and the identification of these patients is important. However, the diagnosis of perioperative MI can be difficult in many cases. The cardiac troponins are biomarkers with high cardiospecificity, and the aim of this study was to assess cTnI and cTnT among other cardiac biomarkers after thoracotomy and lung surgery. METHODS: 24 consecutive patients were included in the final analysis. Venous blood samples were drawn prior to the procedure, 1-3, 4-6, 16-18 and 30-32 h after surgery. Thoracotomy was performed as a standard posterolateral incision on the left or right side under general anesthesia. RESULTS: Both cTnI and cTnT were completely unaffected by the thoracotomy and the lung surgery. Furthermore, no single value of the troponins was above the 99th percentile at any time. In contrast, CK-MB was elevated in nearly half the patients, although the mean values complied well with the reference limit. CK and myoglobin were both considerably elevated and did not discriminate between acute myocardial infarction and release of the markers due to extracardiac injury. CONCLUSIONS: Only the troponins were unaffected by extracardiac surgery and were, thus, reliable markers of myocardial injury in patients who underwent thoracotomy and lung surgery. If the troponins are unavailable, CK-MB mass combined with the CK-MB/CK percentage should be preferred.