Troponin T, creatine kinase MB mass, and creatine kinase MB isoform ratio in the detection of myocardial damage during non-surgical coronary revascularization

International Journal of Cardiology 60 (1997) 7–13

Troponin T, creatine kinase MB mass, and creatine kinase MB isoform ratio in the detection of myocardial damage during non-surgical coronary revascularization Bernhard Reimers a , Mattia Lachin b , Luisa Cacciavillani a , Sandra Secchiero c , Angelo Ramondo d , Giambattista Isabella d , Armando Marzari a , Martina Zaninotto b , Mario Plebani b , c , Raffaello Chioin d , a a, Francesco Maddalena , Sergio Dalla-Volta * b

a Divisione e Cattedra di Cardiologia, University of Padova, Padova, Italy Dipartimento di Medicina di Laboratorio, University of Padova, Padova, Italy c Centro di Ricerca Biomedica, Castelfranco-Veneto ( TV), Italy d Servizio di Emodinamica, University of Padova, Padova, Italy

Received 11 September 1996; revised 11 February 1997; accepted 11 February 1997

Abstract The presence of myocardial injury during non-surgical coronary revascularization has been evaluated by means of highly specific and sensitive biochemical markers. Troponin T, creatine kinase-MB isoenzyme mass concentration, and creatine kinase MB2 / MB1 isoform ratio have been determined in 80 patients who underwent coronary revascularization with percutaneous transluminal coronary angioplasty (PTCA). Forty-five patients underwent balloon angioplasty, 15 rotational atherectomy, 10 directional atherectomy, and 10 elective coronary stenting. Serum concentration of the evaluated markers did not increase significantly after 57 uncomplicated revascularization procedures, including 15 rotablation procedures, nor after 8 PTCAs complicated by localized coronary type B and C dissections. Significant elevation of all markers above the upper limits of the reference interval (P,0.05) was detected after occlusion of small side branches (,0.5 mm diameter) in 5 patients. Creatine kinase MB2 / MB1 isoform ratio was the earliest marker to increase. After recanalization of occluded vessels in 8 / 10 patients with 6–60 days old myocardial infarction only troponin T concentrations increased from a baseline of 0.28 m g / l to a median peak of 0.80 m g / l. This increase was statistically not significant (P50.12). In conclusion, myocardial damage was not detected following uncomplicated non-surgical revascularization obtained with different techniques. Markers of myocardial injury provide high sensitivity after small side branch occlusion.  1997 Elsevier Science Ireland Ltd. Keywords: Coronary angioplasty; Creatine kinase; Troponin T

1. Introduction During non-surgical coronary revascularization, myocardial injury might occur either as a conse*Corresponding author, Cattedra di Cardiologia, Policlinico, Via Giustiniani, 2, 35100 Padova, Italy. Tel.: 139 49 8212310.

quence of transient ischemia during balloon inflation [1] or because of complications of the revascularization procedure such as vessel occlusion, localized coronary dissection, vessel rupture, thrombosis, dislocation of thrombotic material, and vessel spasm [2,3]. New laboratory techniques allow the assay of highly specific and sensitive markers of myocardial

0167-5273 / 97 / $17.00  1997 Elsevier Science Ireland Ltd. All rights reserved PII S0167-5273( 97 )02958-6

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cell damage on peripheral blood samples. These markers are already routinely used in the diagnosis of acute myocardial infarction. Cardiac troponin T [4,5], creatine kinase (CK) MB mass concentration [6], and CK MB isoforms [7,8] are particularly useful not only for diagnosis of myocardial infarction, but also in the detection of minor degrees of myocardial damage (myocarditis, reperfusion injury, heart surgery etc.) [9–13]. The value of troponin T and troponin I in the contest of acute coronary syndromes has been shown in recently published large scale trials [14,15]. Cardiac troponin T provides valuable information also in case of unreliable CK and CK MB activity measurements in patients with skeletal muscle injury such as trauma, surgery, myopathies etc. [16]. The presence of myocardial injury during percutaneous transluminal coronary angioplasty (PTCA) has been evaluated with ‘old’ (CK) and ‘new’ (troponin T, CK MB mass concentration, and CK MB isoforms) serum markers in course of balloon angioplasty, rotational atherectomy, directional atherectomy, and coronary stenting. Previous studies gave controversial information about the release of markers after uncomplicated PTCA [10,17–22]. In particular after rotational atherectomy cardiospecific enzyme release has been reported [23].

2. Patients and methods Eighty patients who underwent non-surgical coronary revascularization were studied prospectively (representing 49% of PTCA procedures of our laboratory during the 6 months of this study): 35 patients underwent balloon angioplasty, 10 coronary stent implantation, 15 rotational atherectomy, and 10 directional coronary atherectomy. In 10 patients with 6–60 days old myocardial infarction and postinfarctual angina a totally occluded vessel was recanalized before PTCA. Patients of each of the 5 different treatment groups were consecutive. Informed consent was obtained from each patient and the study protocol conformed to the guidelines of the 1975 Declaration of Helsinki. Sixty-four percent of patients were male with a mean age of 58.7 years (range 48–72). Forty-eight patients (60%) had symptoms of stable

angina and 32 (40%) of unstable angina. In 70% of patients one vessel, in 22% two vessel, and in 8% three vessel disease was present. Collateral blood flow was present in 22%. Lesion calcifications were observed in 6 patients (8%) and lesion eccentricity in 25 (33%). In all cases revascularization was performed on a single vessel: in 34 cases (45%) on the left anterior descendent artery, in 25 (34%) on the circumflex artery, and in 16 (21%) on the right coronary artery. Coronary percentage diameter stenosis (measured with calliper using the guiding catheter for calibration) of the treated vessel before the procedure was .70% (mean 87.5%; range 70– 100). During revascularization 60 patients (80%) had chest pain and 62 (83%) showed ST changes on the ECG. Seven patients (9%) developed non-sustained chest pain within 12 h from the procedure and 20 (27%) had permanent T wave alterations. For balloon angioplasty different types of balloon catheters were used; the number of inflations varied from 3 to 5 with a mean total inflation time of 175 s (range 110–290); the maximum time of a single inflation was 120 s and the mean inflation pressure was 6.76 atm (range 4–8 atm). For coronary stenting, Palmaz-Schatz stents [24] (Johnson and Johnson Interventional Systems, Warren, NJ) were applied; coronary rotational atherectomy [25] (Rotablator, Heart Technology, Inc., Bellvue, Washington) was performed along with complementary balloon angioplasty; directional coronary atherectomy was performed with the Simpson AtheroCath Device [26] (Devices for Vascular Interventions, Redwood City, CA). Recanalization of occluded coronary vessels was obtained using the guide wire technique followed by balloon angioplasty. The presence of collateral blood flow to the stenotic or occluded vessel was evaluated on the angiogram; the diameter of the side branches and the diameter stenosis of the coronary arteries were measured by calliper. Peripheral blood samples were obtained immediately before (5baseline), and 30 min, 2 h, 6 h, 12 h, 24 h and 48 h after the revascularization procedure [27]. The catalytic concentration of CK was determined according to the IFCC recommended method [28], at 378C, with a Cobas Fara Centrifugal Analyzer (Roche Diagnostics, Milano, Italy). The reference value used in this study was ,190 U / l. CK MB mass concentration was measured using an automated fluorometric enzyme

B. Reimers et al. / International Journal of Cardiology 60 (1997) 7 – 13

immunoassay [29] (Baxter Diagnostics Division, Milano, Italy) with a discriminator value of 5 mg / l. CK-MB isoforms were separated by a high voltage electrophoresis procedure [30] (REP, Helena Laboratories, Milano, Italy) and quantified by reading of fluorescence on a dedicated densitometer. CK-MB isoforms values were expressed as MB2 / MB1 ratio; the reference value was #1. The determination of troponin T was performed by an enzyme immunoassay (ELISA Troponin T, Boehringer Mannheim Italia, Milano, Italy) based on a single-step sandwich principle, with streptavidin-coated tubes as the solid phase and two monoclonal, anti-human cardiac troponin T antibodies [5,31]. The assay was carried out using the microprocessor-controlled Boehringer Mannheim ES-300 photometer. The reference range was 0–0.1 m g / l. Laboratory results were expressed as median values. For statistical analysis the MannWhitney U test for non-parametric values was used; P values ,0.05 indicated statistical significance.

3. Results All patients of this series were successfully revascularized. Mean residual diameter stenosis was 24.7% (range 0–40%). In 57 / 70 of PTCAs on an open vessel the procedure was uncomplicated (81%) (22 were balloon angioplasties, 10 elective stent implantations, 15 rotational atherectomy, and 10 directional atherectomies) and no significant increase of the evaluated parameters from the baseline values was detected (Table 1). After rotational atherectomy a slight, statistically not significant increase of

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troponin T (P50.13) and CK MB mass (P50.10) was observed. The presence of collateral blood flow to the treated vessel, chest pain, and ECG changes during and after the procedure did not influence the results. Localized coronary dissection (type B and C of the NHBLI classification [32]) during balloon angioplasty of an open vessel occurred in 13 / 70 patients (19%). In 8 of these the biochemical parameters remained within the normal range (Table 1); in the remaining 5 / 13 patients, requiring coronary stenting to cover the dissection, occlusion of a small side branch (#0.5 mm diameter) was evidenced on the angiogram and significantly increased values of troponin T (median peak50.81 m g / l; P50.04), MB2 / MB1 ratio (median peak54.00; P50.027), and CK MB mass (median peak 14.1 m g / l; P50.03) were detected in all 5 patients. In 2 / 5 patients CK serum levels were above the upper limit of the reference interval ($190 U / l), the median peak of CK in all 5 patients was 195 U / l. This median increase from baseline was statistically not significant (P50.11) (Table 2; Fig. 1a and Fig. 2). In 8 / 10 patients (80%) who underwent coronary recanalization the troponin T concentrations increased. The serum concentrations of this group (n5 10) increased from an already slightly elevated baseline level (median 0.28 m g / l) to a median peak of 0.80 m g / l; the difference between values was statistically not significant (P50.12). CK MB isoform ratio increased from 0.73 to 0.92 (P50.37) remaining within the reference interval (#1). The other markers did not rise above the reference limits (Table 3; Fig. 1b).

Table 1 Biochemical markers after nonsurgical coronary revascularization (n580) n Reference range Uncomplicated PTCA -balloon angioplasty -primary stenting -rotational ablation -directional atherectomy Complicated PTCA -dissection (type B, C) -side branch occlusion Recanalization and PTCA

52 22 10 15 10 13 8 5 10

Troponin T 0–0.10 mg / L

CK 0–190 U / L

CK-MB 0–5 mg / L

MB2 / MB1 #1

0.02 0.05 0.09 0.05

56 57 60 65

0.30 (0.05) 0.25 (0.25) 2.25 (0.50) 1.37 (0.30)

0.00 0.00 0.00 0.00

0.85 (0.00) 14.1 (0.00) 1.75 (1.10)

0.00 (0.00) 4.00 (0.00) 0.96 (0.73)

(0.00) (0.01) (0.04) (0.03)

0.05 (0.02) 0.81 (0.01) 0.80 (0.28)

(48) (44) (54) (41)

49 (36) 195 (30) 63 (58)

Results expressed as median of peak values (median of values before revascularization5baseline)

(0.00) (0.00) (0.00) (0.00)

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Table 2 Biochemical markers in PTCA complicated by occlusion of small side branches (n55) Normal values

TnT 0-0.10 mg / L

CK 0-190 U / L

CK-MB 0-5 mg / L

MB2 / MB1 #1

before-PTCA 30 min 2h 6h 12 h 24 h 48 h

0.01 (0.00–0.03) 0.02 (0.00–0.02) 0.03 (0.01–0.06) 0.25 (0.05–0.47) ]]]] 0.81 (0.09–1.83) 0.42 (0.23–1.64) 0.31 (0.15–0.88)

30 (22–45) 26 (19–37) 37 (19–39) 76 (54–180) 195 (103–299) ]]]] 103 (65–238) 54 (42–64)

0.0 (0.0–0.0) 0.0 (0.0–0.3) 3.6 (0.0–5.5) 10.0 (1.4–18.5) ]]]] 14.1 (2.1–31.2) 9.7 (4.5–20.8) 1.2 (0.0–2.7)

0.00 (0.0–0.0) 0.00 (0.0–0.0) 2.45 (0.0–2.8) ]]]] 4.00 (1.9–4.9) 2.31 (1.4–3.2) 0.79 (0.6–1.1) 0.75 (0.5–1.0)

Results expressed in median of values (range) first elevated value after PTCA

4. Discussion In this study, successful and uncomplicated coronary revascularization was not followed by release of the evaluated markers for myocardial damage. This seems to confirm that transient ischemia caused by balloon inflation and vessel injury during PTCA does not cause myocardial damage. Previous studies described release of markers of myocardial injury after PTCA, but less specific markers such as CK [17], CK MB enzyme activity assay, myoglobin [18], and CK MM isoforms [19] were considered. Higher

Fig. 1. (a) Representative patterns of marker release in one patient where PTCA was complicated by localized coronary dissection with angiographic evidence of occlusion of a small side branch. Increased Troponin T (TnT) serum levels and increased CK MB2 / MB1 ratio are clearly shown; (b) representative patterns of increased Troponin T serum levels and normal CK MB2 / MB1 ratio of one patient after recanalization of an occluded coronary artery.

specificity of the markers together with advanced, less traumatic PTCA techniques could explain the absence of detectable myocardial damage in the present study. Similar results were obtained by Talasz et al. [21] who could not detect any increase of CK

Fig. 2. LAO view of a left anterior descending artery at baseline (left) and after stenting (right); the occluded side branch is indicated by the arrow.

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Table 3 Biochemical markers in recanalization of a completely occluded vessel before PTCA (n510) Normal values

TnT 0–0.10 mg / L

CK 0–190 U / L

CK-MB 0–5 mg / L

MB2 / MB1 #1

before-PTCA 30 min 2h 6h 12 h 24 h 48 h

0.288 (0.02–3.20) 0.30 (0.02–3.95) 0.57 (0.03–3.93) 0.80 (0.04–6.03) ]]]] 0.77 (0.04–4.27) 0.52 (0.02–2.71) 0.12 (0.02–0.13)

58 (18-86) 58 (18-86) 63 (20–91) ]]] 61 (20–93) 61 (19–102) 59 (19–96) 31 (22–77)

1.1 (0.0–3.1) 0.8 (0.0–2.9) 1.1 (0.0–4.4) 1.8 (0.3–7.1) ]]] 1.7 (0.0–6.2) 1.2 (0.0–3.8) 0.0 (0.0–1.6)

0.73 (0.0–0.8) 0.87 (0.0–0.9) 0.92 (0.0–0.9) ]]]] 0.70 (0.0–0.8) 0.70 (0.0–0.8) 0.96 (0.0–1.1) 0.00 (0.0–0.0)

Results expressed in median of values (range) median of peak values ]]]]]

MB mass and troponin T in serum of patients who underwent uncomplicated balloon angioplasty. Rotational coronary ablation, which causes the pulverization of the atheromatous plaque into small particles with possible distal embolization [25], led to a slight increase of troponin T and CK MB mass confirming previous reports [23] but the upper limit of normal values was not exceeded and the increase from median baseline to median peak levels was not significant. In course of directional atherectomy a small balloon pushes the catheter to one side of the vessel occluding the vessel completely [26]. This method causes short transient ischemia but atheromatous material should not be liberated into the vessel. Unelevated serum markers after directional coronary atherectomy seem to confirm the absence of myocardial injury. Coronary stenting [24], which required a shorter balloon inflation time than balloon angioplasty (120 vs. 175 s), did not cause marker increase from baseline levels. Localized coronary dissection is a frequent complication of non-surgical revascularization [2]. In this study, angiographically detectable dissection occurred in 13 patients (17%). The absence of marker release in 8 patients with type B and C [32] dissection, suggests that this type of lesion confined to the vessel wall does not cause myocardial damage. Kugelmass et al. [22] who evidenced CK MB isoform elevation in 11.5% of directional atherectomy and stent procedures, correlated these positively with an adverse morphology of the treated lesion (thrombus, calcification, eccentricity); this observation could not be confirmed during the present study as far as calcifications and eccentricity are concerned. Lesions with filling defects suggestive for thrombus have not been

treated during the study. Side branch occlusion, filling defects, and dissection were observed by the above authors in only 16% of cases with CK MB isoform elevation, whereas 25% of these cases presented transient slowing of distal coronary flow. The latter phenomenon was not observed in the present study, possibly because PTCA was performed on lesions presenting a lower risk of complications. The occlusion of small side branches which occurred without any alteration of the ECG suggestive of myocardial lesion and / or necrosis, without alterations of the regional wall movement and without prolonged chest pain, induced a significant increase of the levels of troponin T, CK MB mass, and CK MB2 / MB1 isoform ratio. The same observations were reported by Talasz et al. [21], who detected raised CK MB mass levels in all patients with angiographically documented occlusion of small vessels after PTCA and in 3 / 5 patients increased troponin T levels also. These data confirm the high sensitivity of the used biochemical markers: myocardial damage was detected in the absence of clinical signs after occlusion of narrow vessels with an angiographically detected diameter of ,0.5 mm which vascularizes only a small area of myocardium. The high sensitivity of troponin T, CK MB mass, and CK MB isoforms in the detection of myocardial damage has been reported not only after myocardial infarction, but also after heart contusion, endurance exercise, myocardial inflammatory diseases, and acute ischemic syndromes [11,14–16]. The first marker to increase after side branch occlusion was the MB2 / MB1 ratio (2 h), while serum troponin T elevations persisted the longest (.48 h) (Table 2). Peak values of troponin T and MB2 / MB1 were reached after 12 and 6 h respective-

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ly. These data correspond to findings during acute myocardial infarction [4,6,7]. The less specific marker CK increased after side branch occlusion, but the increase was statistically not significant (P50.11) and only in 2 / 5 patients the upper limit of the reference range (0–190 U / l) was surpassed. In patients with previous myocardial infarction (6–60 days old) median baseline troponin T levels were slightly above the upper limit of the reference range (0.28 m g / l; normal #0.1 m g / l) and increased after recanalization of the occluded vessels. This troponin T release might be due to late wash-out after restored blood flow as none of the occluded vessels had collateral flow [12]. The reason that after recanalization only troponin T serum levels increased might be due to the fact that troponin T is a structural and cytoplasmatic protein and not cytoplasmatic only as for the CK complex [5]. The presence of reperfusion injury as described after successful thrombolytic therapy in the course of myocardial infarction [33] or distal embolization of thrombotic material could explain this behavior but the lack of a significant release of CK MB isoform and CK MB mass makes a new event of myocardial damage unlikely. Troponin T has been proposed as a marker of reperfusion to a previously ischemic area also after long periods of interrupted blood flow [12,16] but further investigations are necessary.

5. Study limitations The number of patients with release of troponin T, CK MB mass, and CK MB isoforms is too small to allow definite considerations. In this study patients with skeletal muscle injury were not considered, therefore conclusions on the specificity of the used markers can only be limited. This study was not designed to evaluate coronary reperfusion. The observation of increased troponin T values after late recanalization needs to be confirmed by a higher number of patients and to be compared with early reperfusion.

6. Conclusions Myocardial damage was not detected with highly specific and sensitive biochemical markers, after

uncomplicated non-surgical coronary revascularization obtained with various techniques. It was also not detected after PTCA complicated by type B and C coronary dissection. The determination of troponin T, CK MB mass, and CK MB isoforms provides a high sensitivity in the detection of myocardial injury after occlusion of small side branches, with the CK MB2 / MB1 ratio being the earlier marker.

References [1] Fishbein MC. Creatine kinase release after brief coronary occlusion. J Am Coll Cardiol 1985;6:1304–1305. [2] Sanborn TA, Faxon DP, Haundelshild C, Gottsman SB, Ryan TJ. The mechanism of transluminal angioplasty. Circulation 1983;68:1136–1148. [3] Topol EG. Emerging strategies for failed percutaneous coronary angioplasty. Am J Cardiol 1989;63:249–261. [4] Katus HA, Remppis A, Neumann FJ et al. Diagnostic efficiency of Troponin T measurements in acute myocardial infarction. Circulation 1991;83:902–912. [5] Katus HA, Looser S, Hallermayer K et al. Development and in vitro characterization of a new immunoassay of cardiac troponin T. Clin Chem 1992;38:386–393. [6] Mair J, Artner-Dworzak E, Dienstl A et al. Early detection of acute myocardial infarction by measurement of mass concentration of creatine kinase MB. Am J Cardiol 1991;68:1545–1550. [7] Wu AHB. Creatine kinase isoforms in ischemic heart disease. Clin Chem 1989;35:7–13. [8] Jaffe AS, Serota H, Grace A, Sobel BE. Diagnostic changes in plasma creatine kinase isoforms early after the onset of acute myocardial infarction. Circulation 1986;74:105–109. ¨ [9] Katus HA, Kubler W. Detection of myocardial cell damage in patients with unstable angina by serodiagnostic tools. In: Bleifeld W et al., eds. Unstable angina. Berlin: Springer-Verlag, 1990;93–100. [10] Hossein-Nia M, Kallis P, Brown PA et al. Creatine kinase MB isoforms: sensitive markers of myocardial damage. Clin Chem 1994;7:1265–1271. [11] Hamm CW, Ravklide J, Gerhardt W et al. The prognostic value of serum troponin T in unstable angina. N Engl J Med 1992;327:146– 150. [12] Abe S, Arima S et al. Early assessment of reperfusion therapy using cardiac troponin T. J Am Coll Cardiol 1994;23:1382–1389. [13] Donelly R, Hillis WS. Myocardial injury: cardiac troponin T. Lancet 1993;341:410–411. [14] Ohman EM, Armstrong PW, Christenson RH et al. for the GUSTOIIa investigators. N Engl J Med 1996;335:1333–1341. [15] Van De Werf F. Cardiac troponins in acute coronary syndromes. N Engl J Med 1996;335:1388–1389. [16] Mair J, Dienstl F, Puschendorf B. Cardiac troponin T in the diagnosis of myocardial injury. Clin Lab Sci 1992;29:31–57. [17] Oh JK, Shub C, Ilstrup DM, Reeder GS. Creatine kinase release after successful percutaneous transluminal coronary angioplasty. Am Heart J 1985;109:1225–1230. [18] Pauletto P, Piccolo D, Scannapieco G et al. Changes in myoglobin, creatine kinase and creatine-kinase-MB after percutaneous transluminal angioplasty for stable angina pectoris. Am J Cardiol 1987;59:999–1000.

B. Reimers et al. / International Journal of Cardiology 60 (1997) 7 – 13 ¨ [19] Schofer J, Lampe F, Mathey DG, Muller-Hansen S, Voigt KD. Anstieg der kreatinkinase und ihrer MM-isoformen nach erfolgreicher und unkomplizierter koronarangioplastie. Z Kardiol 1992;81:326–330. [20] Hunt AC, Chow SL, Shiu MF, Chilton DC, Cummins B, Cummins P. Release of creatine kinase-MB and cardiac specific troponin-I following percutaneous transluminal coronary angioplasty. Eur Heart J 1991;12:690–694. [21] Talasz H, Oenser N, Mair J et al. Side-branch occlusion during percutaneous transluminal coronary angioplasty. Lancet 1992;339:1380–1382. [22] Kugelmass AD, Cohen DJ, Moscucci M et al. Elevation of the creatine kinase myocardial isoform following otherwise successful directional coronary atherectomy and stenting. Am J Cardiol 1994;74:748–754. [23] Warth D, Leon M, O’Neill W, Zacca N, Polissar N, Buchbinder M. Rotational atherectomy multicenter registry: acute results, complications and 6-month angiographic follow-up in 709 patients. J Am Coll Cardiol 1994;24:641–648. [24] Schatz RA, Baim DS, Leon M et al. Clinical experience with Palmaz-Schatz coronary stent: initial results of a multicenter study. Circulation 1991;83:148–161. [25] Bertrand ME, Lablanche JM, Leroy F et al. Percutaneous transluminal coronary rotary ablation with Rotablator (European experience). Am J Cardiol 1992;69:470–474. [26] Hinohara T, Selmon MR, Robertson GC, Braden L, Simpson JB. Directional atherectomy: new approaches for treatment of obstructive coronary and peripheral vascular disease. Circulation 1990;81(suppl IV):79–91.

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[27] Gerhardt W, Ljungdahl L. Rational diagnostic strategy in diagnosis of ischemic myocardial injury. S-troponin T and S-CK MB (mass) time series using individual baseline values. Scand J Clin Lab Invest 1993;53(suppl 215):47–59. [28] International Federation of Clinical Chemistry. IFCC methods for the measurement of catalytic concentration of enzymes. Part 7. IFCC method for creatine kinase (ATP: creatine N-phosphotransferase, EC 2.7.3.2). IFCC recommendation. Clin Chim Acta 1990;190:S4–S40. [29] Chappelle JP, El Allaf M. Automated quantification of creatine kinase MB isoenzymes in serum by radial partition immunoassay, with use of the Stratus analyzer. Clin Chem 1990;36:99–101. [30] Puleo PR, Guadagno PA, Roberts R, Perryman MB. Sensitive, rapid assay of subforms of creatin kinase MB in plasma. Clin Chem 1989;35:7–13. [31] Burlina A, Zaninotto M, Secchiero S, Rubin D, Accorsi F. Troponin T as a marker of ischemic myocardial injury. Clin Biochem 1994;27:113–121. [32] Sharma SK, Israel DH, Karrean JL, Bodian CA, Ambrose JA. Clinical, angiographic, and procedural determinants of major and minor coronary dissections during angioplasty. Am Heart J 1993;126:39–47. [33] Forman MB, Virmani R, Puett DW. Mechanisms and therapy of myocardial reperfusion injury. Circulation 1990;81(suppl IV):61– 69.