Exclusion of acute myocardial infarction. The value of measuring creatine kinase slope.

For the exclusion (and diagnosis) of acute myocardial infarction, we studied timed sequential (slope) measurements of creatine kinase and creatine kinase-MB catalytic activity concentration, creatine kinase-MB mass concentration, troponin T and myoglobin, using data from 242 patients consecutively admitted for evaluation of suspected acute myocardial infarction in the 12 hours before admission. Three biochemical strategies based on measurements in two consecutive samples obtained within 12 hours after admission were evaluated. The highest sensitivities were encountered for a biochemical strategy based on the sole measurement of creatine kinase mass concentration (98%) or troponin T (96%) and a strategy based on measurements of creatine kinase activity concentrations, which includes creatine kinase slope calculation and measurement of creatine kinase mass concentration (95%). Both strategies were applied in subgroups of patients based on the electrocardiographic findings. In patients with a normal electrocardiogram, the sensitivity of the strategy using sole measurements of creatine kinase mass concentration was 100%, but this was true for the strategy based on creatine kinase slope measurements, which is the cheaper and therefore preferred procedure for excluding myocardial infarction. This approach, however, does not account for detecting minor myocardial cell damage in patients not yet fulfilling the criteria of the World Health Organization for diagnosing acute myocardial infarction.

Contribution of creatine kinase MB mass concentration at admission to early diagnosis of acute myocardial infarction.

OBJECTIVE: To assess the diagnostic value at admission of creatine kinase MB mass concentration, alone or in combination with electrocardiographic changes, in suspected myocardial infarction. DESIGN: Prospective study of all consecutive patients admitted within 12 hours after onset of chest pain to a coronary care unit for evaluation of suspected myocardial infarction. SETTING: Large regional hospital. PATIENTS: In 297 patients creatine kinase and creatine kinase MB activities and creatine kinase MB mass concentration were determined. Myocardial infarction according to the criteria of the World Health Organisation was diagnosed in 154 patients and excluded in 143 patients (including 70 with unstable angina pectoris). RESULTS: Sensitivity/specificity for creatine kinase MB mass concentration in patients admitted within 4 hours and 4-12 hours after onset of chest pain were 45%/94% and 76%/79% respectively. Corresponding values for creatine kinase activity were 20%/89% and 59%/83%, and for creatine kinase MB activity 16%/87% and 53%/87%. Raised creatine kinase MB mass concentration was seen in 17% of patients with unstable angina pectoris. Stepwise logistic regression analysis showed that independent predictors of acute myocardial infarction in patients admitted within 4 hours after onset of chest pain were electrocardiographic changes and creatine kinase MB mass concentration on admission; in patients admitted 4-12 hours after the onset of pain independent predictors were electrocardiographic changes and creatine kinase MB mass concentration and activity. CONCLUSION: Creatine kinase MB mass concentration is a more sensitive marker for myocardial infarction than the activity of creatine kinase and its MB isoenzyme. Electrocardiographic changes on admission in combination with creatine kinase MB mass concentration (instead of creatine kinase and creatine kinase MB activities) are best in diagnosing myocardial infarction.

Troponin T and myoglobin at admission: value of early diagnosis of acute myocardial infarction.

We studied the predictive power at admission of troponin T and myoglobin and compared them with that of CK and CK-MB activity and ECG in 290 consecutive patients admitted for evaluation of a suspected AMI. The likelihood ratio for an ischaemic ECG at admission < 4 h (between 4 and 12 h) after onset of chest pain was 2.85 (1.92), for a inconclusive ECG 1.53 (1.98) and for a normal ECG 0.27 (0.35). In patients admitted < 4 h after onset of chest pain, the likelihood ratio for abnormal and normal myoglobin concentrations (8.06 and 0.67) was considerably better for detection of AMI as defined by the WHO criteria than for the other markers, including the ECG. In patients admitted 4-12 h after onset of chest pain, the likelihood ratios for abnormal and normal myoglobin concentrations were 4.88 and 0.42; for troponin T 3.11 and 0.31; for CK activity 3.44 and 0.49 and for CK-MB activity 4.08 and 0.54 respectively. The sensitivity for troponin T (64%) was better than that of the other markers but its specificity (74%) was worse, because in patients with unstable angina troponin T was frequently elevated (37%). Stepwise logistic regression analysis showed that the best predictors of AMI within 4 h after onset of chest pain were the ECG and myoglobin and between 4-12 h after onset of chest pain the ECG, CK-MB activity and myoglobin.

The mass concentrations of serum troponin T and creatine kinase-MB are elevated before creatine kinase and creatine kinase-MB activities in acute myocardial infarction.

The time-related frequency of elevated results for the mass concentrations of the MB isoenzyme of creatine kinase and of troponin T were compared with that of creatine kinase and creatine kinase-MB activity in patients with acute myocardial infarction. Patients (322; 175 with and 147 without myocardial infarction) consecutively admitted for evaluation of possible acute myocardial infarction were investigated. Reference limits for troponin T (0.1 microgram/l) and creatine kinase-MB mass concentration (5.0 micrograms/l) were exceeded frequently in patients with unstable angina pectoris (troponin T 43%, creatine kinase-MB mass concentration 24%) in contrast to patients with no acute ischaemic heart disease (both < 5%). Within 4 and between 4-8 hours after onset of chest pain, the frequency of elevated results for creatine kinase-MB mass concentration and troponin T in patients with acute myocardial infarction was considerably higher (20-30%) than for creatine kinase and creatine kinase-MB activity. Creatine kinase-MB mass concentration and troponin T both allowed earlier diagnosis of acute myocardial infarction than creatine kinase and creatine kinase-MB activity, but troponin T was not elevated before the creatine kinase-MB mass concentration.

Failure of new biochemical markers to exclude acute myocardial infarction at admission.

In a substantial proportion of patients with suspected myocardial infarction, biochemical markers are needed for clinical decision-making at the time of admission, because electrocardiographic (ECG) recordings are inconclusive. We have assessed the usefulness for exclusion of myocardial infarction at admission of the newer markers creatine kinase MB (CK-MB) mass concentration, troponin T, and myoglobin in comparison with the routinely used markers creatine kinase (CK) and CK-MB activity. 290 consecutive patients were enrolled. Acute myocardial infarction was diagnosed on the basis of clinical history, ECG criteria, and time-dependent changes in CK and CK-MB activity. 153 patients had definite acute myocardial infarction. Troponin T had the highest sensitivity for prediction of acute myocardial infarction; high concentrations (above the upper reference limits) were found in 98 (64%) of the patients with infarctions compared with 92 (60%) for CK-MB mass concentration, 76 (50%) for myoglobin, 61 (40%) for CK activity, and 53 (35%) for CK-MB activity. However, troponin T also had the highest "false-positive" rate; of 137 patients without myocardial infarction, 36 (26%) had high troponin T concentrations. Sensitivity, specificity, and positive and negative predictive values were calculated in relation to time between onset of chest pain and hospital admission. Although CK-MB mass concentration was, by a small margin, the best marker in patients admitted within 8-10 h of onset of chest pain, all the markers had negative predictive values too low to allow exclusion of acute myocardial infarction at admission in patients with symptoms suggestive of myocardial infarction of less than 10 h duration.

An 8-week double-blind study of amlodipine and diltiazem in patients with stable exertional angina pectoris.

A multicenter, double-blind study was performed to compare the antianginal efficacy and safety of the new dihydropyridine calcium antagonist amlodipine with the benzothiazepine calcium antagonist diltiazem in patients with stable exertional angina pectoris. Following a 2-week placebo run-in period, 39 patients were randomized to receive amlodipine (2.5-10 mg once daily) and 41 patients to receive diltiazem (60-120 mg three times daily) in an 8-week double-blind treatment phase. The study used standardized bicycle exercise testing as a primary efficacy assessment. Patients also recorded angina frequency and nitroglycerin (NTG) tablet consumption/ week. Treatment with amlodipine and diltiazem resulted in an improvement in total exercise time, time to angina and total work, mean ST-segment deviation at maximum common load, median number of angina attacks/week, and NTG tablet consumption/week. The incidence and severity of possibly treatment-related side effects and laboratory test abnormalities were comparable for both drugs. The most frequently reported side effects were dizziness, headache, peripheral edema, and nausea. Two patients withdrew from diltiazem treatment due to pruritus in one case and severe headache and moderate dyspnea in the other. No amlodipine-treated patients withdrew due to side effects. In conclusion, this study demonstrated that the antianginal efficacy and tolerability of amlodipine is equivalent to diltiazem, but amlodipine has the advantage of once-daily dosing.

Transesophageal echocardiography during percutaneous balloon mitral valvuloplasty.

To ascertain the value of transesophageal echocardiography during percutaneous balloon mitral valvuloplasty, the present study was undertaken in 26 anesthesized patients (21 women and 5 men; mean age, 47 years) with symptomatic rheumatic mitral valve stenosis. In all but one patient the balloon dilation of the mitral valve was successful and Doppler-derived valve area increased (0.9 +/- 0.3 to 1.9 +/- 0.4 cm2). Transesophageal echocardiography provides continuous monitoring, as well as guidance of the procedure. Crossing the arterial septum, as well as delivery of the sheath through the mitral valve orifice and correct positioning of the balloon, was highly facilitated and reduced x-ray exposure time. The degree of mitral regurgitation and the presence of interatrial shunting at the end of the procedure could be readily assessed, making cineangiography not necessary. Complications of the procedure, such as pericardial effusion, could be detected before hemodynamic deterioration had occurred (one patient). The advantages of transesophageal echocardiography for routine monitoring of percutaneous mitral valvuloplasty, however, should be weighted against the added risk and expense of this support.

Comparison of iohexol and ioxaglate in selective coronary angiography.

The hemodynamic effects of two low osmolar contrast media, iohexol and ioxaglate, were compared in 24 patients undergoing selective coronary angiography because of suspected significant coronary heart disease. Neither medium had a significant effect on left ventricular function when injected into the left or right coronary artery. The image quality and radiological value of the media were similar. Mild side effects were suffered by 14 patients but no statistical difference was shown between the media as to the number of adverse reactions.