Role of CPK and EKG in Dx of MI =============================== þ Mercy Values: - as of Dec 16, 1996, reference range is: + CK-MB <= 5.0 ng/ml + RI <= 2.5 + cTnI <= 1.5 ng/ml (as of 11/13/98) RI is (CK-MB/CK total) x 100 (percent CK-MB, in other words) þ MB is better than EKG Hedges JR, Young GP, Henkel GF, Gibler WB, Green TR, Swanson JR Serial ECGs are less accurate than serial CK-MB results for emergency department diagnosis of myocardial infarction. Ann Emerg Med 1992 Dec;21(12):1445-50 HYPOTHESIS: Serial creatine kinase-MB (CK-MB) levels provide more accurate predictive information regarding myocardial infarction than serial ECGs in emergency department patients with chest discomfort and no ST-segment elevation on the initial ECG. DESIGN: Prospective, observational study. SETTING: University hospital and university-affiliated Veterans Affairs Medical Center EDs. PARTICIPANTS: Two hundred sixty-one patients 30 years or older with chest discomfort warranting an ECG and consenting to observation. Exclusions included hemodynamic or rhythm instability and ST-segment elevation of 0.1 mV or more in two or more electrically contiguous leads at presentation. MEASUREMENTS: ECGs were obtained at presentation and three to four hours after presentation. Significant serial ECG changes sought on comparison of initial and three- to four-hour ECGs were 0.05 mV or more ST elevation or depression, Q-wave development, or T-wave inversion changes in two or more electrically contiguous leads. CK-MB levels were obtained at presentation and hourly for three hours (positive level, 8 or more ng/mL). Myocardial infarction was determined by record review and was based on independent CK-MB measurements. RESULTS: Twenty-eight (11%) patients were diagnosed with a myocardial infarction. Thirty-eight (15%) patients had a serial ECG change. Eleven of the myocardial infarction patients (39%) had a serial ECG change compared with 27 (12%) of the non-myocardial infarction patients (P < .001). Sensitivities and specificities of a serial ECG change versus serial CK-MBs for myocardial infarction were 39% versus 68% (sensitivity) and 88% versus 95% (specificity), respectively. Serial CK-MBs were more accurate than a serial ECG change for predicting myocardial infarction (P < .03). CONCLUSION: Serial changes in ECGs during a three- to four-hour interval were associated with the diagnosis of myocardial infarction but were infrequent and less accurate than serial CK-MB levels obtained for the same interval. þ Can have MI with elevated MB but normal CPK total Yusuf S, Collins R, Lin L, Sterry H, Pearson M, Sleight P Significance of elevated MB isoenzyme with normal creatine kinase in acute myocardial infarction. Am J Cardiol 1987 Feb 1;59(4):245-50 The significance of elevated levels of the MB isomer of creatine kinase (CK-MB) when creatine kinase (CK) level is normal was studied in 400 patients with suspected acute myocardial infarction (AMI). In 350 patients both CK and CK-MB were elevated (group 1), in 21 only CK-MB was elevated (group 2), in 24 neither enzyme was elevated (group 3) and in 5 only CK was elevated (group 4). In 57% of patients in group 2 the CK level was doubled, with a characteristic enzyme curve, within the normal range, suggesting that an increase in CK had been missed because arbitrary definitions of "normal" were used. The median CK increase (60 IU/liter) in group 2 was greater than that in group 3 (23 IU/liter) (p less than 0.001). Patients in group 1 with small AMIs had a relative increase in CK similar to that in group 2. However, patients in group 2 had a lower baseline CK level so that peak CK did not become abnormally high despite a 5-fold increase in some patients. In patients in group 1 with small AMIs, CK was elevated in fewer samples than CK-MB. If only 2 samples were obtained in all patients, elevation of CK levels would have been missed in 63 group 1 patients, erroneously increasing the number of patients in group 2 fourfold (to 84 of 400, or 21%, instead of 21 of 400, or only 5%). Conversely, if patients in group 2 with a doubling of CK are excluded, the prevalence of elevated CK-MB with normal CK would be only 9 of 400 (2%).(ABSTRACT TRUNCATED AT 250 WORDS) (2) Vladutiu AO, Schachner A Increased creatine kinase (CK) MB isoenzyme in patients with "normal" total CK activity suspected of acute myocardial infarction. J Med 1989;20(1):73-81 Many laboratories screen patients suspected of acute myocardial infarction (AMI) with a test for total creatine kinase (CK) and perform testing for CK-MB isoenzyme only in patients with elevated total CK. To find out whether this practice could result in missing patients with AMI who can have "normal" (within the reference interval) total CK with increased CK-MB (greater than or equal to 5%), we prospectively and sequentially monitored CK and CK-MB in patients admitted for suspected AMI. We found that 12.5% of patients with the final diagnosis of AMI had initially low total CK and high CK-MB (as determined by electrophoresis), but the majority of these patients showed subsequently increased total CK above the reference value. It is suggested that the presence of CK-MB in patients with low total CK does not represent a laboratory error and most of these patients have AMI. Total CK assay could be abandoned in favor of CK-MB testing in patients suspected of AMI. þ Does an IM injection raise CPK or CPK MB? Dunno. [Changes in creatine kinase activity in serum following intramuscular injection] AU: Surber-C; Dubach-UC; Forgo-I SO: Klin-Wochenschr. 1988 Feb 1; 66(3): 96-102 AB: The effect of intramuscular injections of two multivitamin preparations, two excipient preparations without vitamins, and a placebo preparation (glycine 2.5%) on serum creatine kinase activity (S-CK) in ten healthy volunteers (three female, seven male) aged between 23 and 25 years was investigated. One of the multivitamin preparations contained no lidocaine, the other 1% lidocaine. The one excipient formulation was isoosmotic, while the other contained added saline to bring it to the same degree of hyperosomolarity as the multivitamin formulation without lidocaine. The formulations were administered by deep ventrogluteal injection by means of a standardized injection technique. Blood samples were taken before and 6, 12, 24 and 48 h after injection. Following the administration of all the formulations except that of the glycine 2.5%, a marked increase in S-CK activity (1260 I.U./l) was observed 12 h after injection (normal range: male: 47-243 I.U./l, female: 39-226 I.U./l). The relative standard deviation for the 12 h S-CK value was 66.4-97.3%. On applying a threeway analysis of variance to the parameter S-CKmax, no significant differences (alpha = 5%) were found between the effects of the multivitamin and excipient formulations. There was a difference between these and glycine 2.5%, however. There were significant differences between individual volunteers but no significant differences based on the sequence in which the injections were given. With regard to the parameter S-CK AUC (area under the curve, trapezoidal rule), a significant difference (alpha = 5%) was observed only between glycine 2.5% and the multivitamin formulation containing 1% lidocaine; Serum creatine kinase after intramuscular injections. AU: Konikoff-F; Halevy-J; Theodor-E SO: Postgrad-Med-J. 1985 Jul; 61(717): 595-8 AB: Serum creatine kinase (CK) activity was measured after intramuscular injections in 44 patients hospitalized for non-cardiac reasons. The drugs injected were: diazepam, dipyrone, metoclopramide, meperidine, pentazocine and procaine penicillin. Only 3 out of 44 patients (7%) demonstrated significant elevation of CK levels following the intramuscular injections. In these 3 patients the elevation was mainly due to a rise of the MM-isoenzyme fraction with MB levels increased in one patient. These findings do not justify the common clinical notion of regarding intramuscular injections as a frequent cause of serum CK elevation. It is concluded that high CK serum values in a patient with chest pain should always be considered with utmost suspicion, disregarding the possible effects of a previous intramuscular injection. Philippe Le Conte, MD, PhD Emergency Department University Hospital Nantes, France þ Marathon Runners all Have Elevated CPK-MB - [Diamond TH, Smith R, Goldman AP, et al. The dilemma of the creatine kinase cardiospecific iso-enzyme (CK-MB) in marathon runners. S Afr Med J 1983; 63:37-41.] Abstract: