Clinical methods for evaluating infarct size and its anatomic correlations. Study carried out in 193 cases. III. Comparison of data on the evaluation of the infarct size using the QRS score and a method of maximal creatine kinase determination in the serum

AIMS: To compare two methods concerning the clinical evaluation of infarct size--one using a QRS score, the other based on peak Ck values--applied to the same population. CONCEPT AND PLACE OF THE STUDY: to determine--based on previously established correlations between a QRS score and the anatomic total infarct size on one hand, and between the peak CK values and the anatomic recent infarct size on the other hand--which myocardial infarction subgroup constitutes the best indication for each method. The study took place in a Coronary Care Unit of a Central Hospital. MATERIAL AND METHODS: 193 patients who died successively of acute myocardial infarction through out 4 years were studied. After establishing the exclusion critéria, the QRS score was calculated according to the method of Selvester modified by Wagner, and peak CK values were evaluated. Infarct size, either recent or old, was determined by means of an anatomical method developed by the authors and based on Hackel's and Alonso's previous works. Correlations were established between data from each clinical method and those from the anatomical method. Several myocardial infarction subgroups were considered for comparison of the correlations found in each subset. RESULTS AND CONCLUSIONS: As long as QRS score was regarded, significant correlations were found between the evaluation by QRS score and anatomical infarct size in the subgroups of patients with severe pump failure, prior myocardial infarction, or total loss of ventricular muscle mass of at least 20 percent; however, a significant correlation was missing when the whole myocardial infarction group was taken into consideration. When peak CK value were considered, a weak significant correlation was found between the evaluation by enzyme determination and anatomical infarct size in the whole group of patients, but a stronger correlation was present in the subgroups of patients with survival longer than 24 hours, anterior wall myocardial infarction, free wall cardiac rupture, or first acute myocardial infarction. In conclusion the choice of the method to be used in the clinical evaluation of infarct size should take into account the type of population beeing studied, and follow the results obtained in different myocardial infarction subgroups as mentioned above.     

Clinical methods for evaluating infarct size and its anatomic correlations. A study conducted with 193 cases. II. Evaluation of infarct size by determining maximal creatine phosphokinase in serum. Enzimatico-anatomic correlations

AIMS: To compare the infarct size calculated by the peak serum CK method with the anatomic infarct size in a population dying of acute myocardial infarction. CONCEPT AND PLACE OF THE STUDY: To use the method of peak serum CK in the assessment of infarct size, calculated by a method developed by the authors, in a population dying of acute myocardial infarction in a coronary care unit. METHODS: 193 patients who successively died with acute myocardial infarction entered the study. After establishing the exclusion criteria the anatomical infarct size was measured using the method developed by the authors of myocardial slices after fixation of the heart and by the peak CK method. The two methods were correlated using linear regression curves. RESULTS AND CONCLUSIONS: A global correlation between the two methods was found although wide scattered values were found. After dividing the population in several subgroups, the analysis showed that survival below 48 hours, death in left ventricular failure, inferior infarcts and reinfarction influenced negatively this correlation. The anatomical method showed its value for this kind of evaluation having always in mind its known limitations. The enzyme method looked less discriminating as peak CK, obtained by 12 h sampling will seldom reflect the peaks of CK liberation curve. As the study was applied to a population of patients dying of acute myocardial infarction its results cannot be applied without caution to a population of survivors. We anticipate that in such a population peak CK will have a better correlation with real CK peaks even with 12 hours sampling and therefore reflecting more accurately infarct size.     

Intraventricular thrombi in acute myocardial infarct. Clinicoanatomic study carried out in 193 consecutive cases

AIMS: To determine the incidence of intraventricular thrombi in patients who died of acute myocardial infarction, as well as to define the clinico-anatomical parameters of the population with thrombi. CONCEPT OF THE STUDY: To apply a clinical as well as an anatomical protocol of prospective study, in patients who died of acute myocardial infarction. The clinical protocol contemplates 64 parameters and the anatomical protocol contemplates 34. in the anatomical study were used very discriminative technics, already presented in previous papers. PLACE OF THE STUDY: The study took place in a CCU and pathological department of an University Hospital. MATERIAL AND METHODS: 193 patients who died successively of acute myocardial infarction in a CCU between 1983 and 1986. The only criteria for the inclusion in the study was the possibility of doing a necropsy study, which was done in 77% of the patients who died in that period. The study was a prospective one, being excluded only the patients in whom the anatomical study didnt confirm recent myocardial infarction. The clinical data were observed during the stay in the CCU using a protocol developed for this study. In the anatomical study a protocol developed by the authors was applied, using very discriminative anatomical quantification technics of the infarct size as well as of the coronary obstruction degree by atherosclerotic plaques. All data were stored and treated in a computer program developed for this study. RESULTS: From the 193 cases that have been studied, 88 (43%) presented thrombus in at least one of the ventricular cavities, 38 (26%) only in left ventricle, 15 (8%) only in right ventricle and 35 (18%) in both ventricles. The set with thrombus has presented a few characteristics which granted it some individuality. Thus, this group presented: a higher delay between the beginning of acute myocardial infarction and the admission in the CCU (and so in the beginning of the anticoagulant therapy), lower prevalence of diabetes, higher prevalence of left ventricular failure (Killip class III or IV), higher prevalence of cardiogenic shock and so a higher need of inotropic therapy, higher heart weight, higher prevalence of auricular thrombi and bigger infarct size when evaluated by a QRS score. In the group with left ventricular thrombi, the anterior infarct was more frequent and in the group with right ventricular thrombi the right ventricular infarct was also more frequent. The systemic embolism was uncommon in this group (1 case in 193 patients). CONCLUSIONS: 1. The intraventricular thrombi occurs in about half of the patients who died of acute myocardial infarction. 2. The group with thrombi has presented some characteristics which makes it different from the group with no thrombi. 3. The delay in the beginning of the anticoagulant therapy seems to be a risk factor of intraventricular thrombosis.     

Evaluation of a QRS scoring system for estimating myocardial infarct size. II. Correlation with quantitative anatomic findings for anterior infarcts

The ability of an independently developed QRS point score to estimate the size of infarcts predominantly within the anterior third of the left ventricle was evaluated by quantitative pathologic-electrocardiographic correlation. The study was limited to 21 patients with a single infarct documented by postmortem examination, for whom an appropriately timed standard 12 lead electrocardiogram was available that did not exhibit signs of left or right ventricular hypertrophy, left or right bundle branch block or anterior or posterior fascicular block. At necropsy the heart was cut into five to seven slices. The location and size of the infarct was quantitated by computer-assisted planimetry of the slices.The electrocardiogram of 19 (90 percent) of the patients exhibited either a Q wave or an R wave of no more than 20 ms in lead V₂. The infarct in the two patients without this electrocardiographic finding was small, occupying 2 and 3 percent of the left ventricle, respectively. The percent infarction of the left ventricle correlated with the QRS point score (r = 0.80). Thus in patients without complicating factors in the electrocardiogram and with a single infarct, the electrocardiogram provides a marker for infarction in the anterior third of the left ventricle and permits estimation of infarct size.     

Evaluation of a QRS scoring system for estimating myocardial infarct size. IV. Correlation with quantitative anatomic findings for posterolateral infarcts

This study correlated the location and size of posterolateral myocardial infarcts (MIs) measured anatomically with that estimated by quantitative criteria derived from the standard 12-lead ECG. Twenty patients were studied who had autopsy-proved, single, posterolateral MIs and no confounding factors of ventricular hypertrophy or bundle branch block in their ECG. Left ventricular anatomic MI size ranged from 1 to 46%. No patient had a greater than or equal to 0.04-second Q wave in any electrocardiographic lead and only 55% had a 0.03-second Q wave. A 29-point, simplified QRS scoring system consisting of 37 weighted criteria was applied to the ECG. Points were scored by the ECG in 85% of the patients (range 1 to 8 points). MI was indicated by a wide variety of QRS criteria; 19 of the 37 criteria from 8 different electrocardiographic leads were met. The correlation coefficient between MI size measured anatomically and that estimated by the QRS score was 0.72. Each point represented approximately 4% MI of the left ventricular wall.     

Quantification of infarct size by thallium-201 single-photon emission computed tomography using the unfolded map method. Comparison with QRS score and angiographic infarct size at 4 weeks after infarction

A new technique of data processing, the unfolded map method, was used with thallium-201 single-photon emission computed tomography to quantify infarct size in 35 patients with single-vessel disease at 4 weeks after their first myocardial infarction (24 anterior and 11 inferior infarcts), and the results were compared with those obtained by electrocardiography and contrast left ventriculography. The myocardial borders and the infarcted region were defined using the threshold technique and a cutoff value of 55%. Count profile data for each short-axis slice were unfolded zonally into single planes with the same ratio, and their areas were calculated from the slice thickness and radius. Thus, the size of the unfolded map represented the actual left ventricular myocardial area Infarct size was quantitated from the ratio of pixels in the infarcted region to those in the whole map, and the ratio itself was used as the percent infarct size. Although a defect 1 cm in diameter (0.8 cm²) could not be detected in a phantom study, defects ≥ 2 cm in diameter (≥3.1 cm²) could be measured satisfactorily. The infarct size and percent infarct size determined by the unfolded map method correlated well with the QRS score (r = 0.841 and r = 0.838), the percentage of abnormally contracting segments on left ventriculography (r = 0.835 and r = 0.87 7), and the ejection traction (r = -0.835 andr = -0.856). These data indicate that the unfolded map method provides adequate quantification of infarct size, even in the chronic phase, without complicated data processing.     

Comparison of Selvester QRS score with magnetic resonance imaging measured infarct size in patients with ST elevation myocardial infarction

Background and PurposeRecent studies have shown that the Selvester QRS score is significantly correlated with delayed enhancement-magnetic resonance imaging (DE-MRI) measured myocardial infarct (MI) size in reperfused ST elevation MI (STEMI). This study further tests the hypothesis that Selvester QRS score correlates well with MI size determined by DE-MRI in reperfused STEMI.Methods and ResultsThe relationship was evaluated retrospectively in 55 first-time STEMI patients 3 months after receiving primary percutaneous coronary intervention. Selvester QRS score and DE-MRI MI size were significantly correlated, r = 0.41 (P < .01). The difference between the Selvester QRS score and DE-MRI was 5.8% MI of the left ventricle (95% confidence interval, 2.9%-8.6%). Furthermore, increasing difference between Selvester QRS score and DE-MRI was observed with increasing MI size.ConclusionSelvester QRS score correlated only moderately with DE-MRI MI size. Selvester QRS score overestimated MI size.     

Evaluation of a QRS scoring system for estimating myocardial infarct size V. Specificity and method of application of the complete system

The specificity of a previously developed 57-criteria/32-point QRS scoring system for estimating myocardial infarct (MI) size is evaluated in an extensive control population and the method of application of this system for determining a QRS score from a standard 12-lead electrocardiogram is described. Points are accumulated from Q- and R- wave durations, R- and S-wave amplitudes, R/Q- or R/S-amplitude ratios and the presence of R-wave notching, with each point representing approximately 3% of the left ventricle. The subjects were selected because of the minimal likelihood of their having had myocardial infarcts or other sources of QRS modification. There were 500 consecutively selected normal Caucasian subjects, aged 20 to 69 years, with 50 women and 50 men in each of the 5 decades. Specificity for the 57 individual criteria ranged from 89 to 100 %. Fifty-one criteria met the required standard of at least 95 % specificity; of the 6 that failed, 3 were successfully modified to achieve this standard and 3 were eliminated. In the resultant 54-criteria/32-point complete system, the total population, as well as both women and men, required more than 3 points to attain at least 95% specificity. Subjects in each of the 5 decades met the specificity standard either at or below the level of more than 3 points. The point score at which 95% or greater specificity was attained for the 10 age/sex subsets varied. The 60- to 69-year-old men were the least specific subset, achieving this standard at more than 4 points, while the 40- to 49-year-old men were the most specific, requiring only a score of more than 1 point. Thus, the complete scoring system is specific overall in the adult Caucasian population studied here. However, because the specificity of many criteria were dependent on age and sex, this system must be further evaluated by consideration of a more comprehensive database.     

Evaluation of a QRS scoring system for estimating myocardial infarct size. VI: Identification of screening criteria for non-acute myocardial infarcts

Each of the 54 criteria in the Selvester 32-point QRS scoring system for estimation of myocardial infarct (MI) size has attained greater than or equal to 95% specificity in normal subjects. This study was performed to identify a subset of those criteria with cumulative specificity greater than or equal to 95% and maximal sensitivity for use in screening for the presence of non-acute MI. Coronary angiography and left ventriculography were used to identify 500 normal subjects, 60 patients with isolated anterior MI and 62 patients with isolated inferior MI. Patients with the QRS confounding factors of ventricular hypertrophy, fascicular block or bundle branch block on their electrocardiogram were not included. Using stepwise logistic regression analysis, the screening criteria identified were: (1) Q greater than or equal to 30 ms in aVF, (2) R less than or equal to 10 ms and less than or equal to 0.1 mV in V2 and (3) R greater than or equal to 40 ms in V1. Cumulatively, these 3 screening criteria achieved 84% and 77% sensitivities for inferior and anterior MI groups, respectively. Thus, a set of 3 criteria from the Selvester QRS scoring system is capable of identifying single non-acute anterior or inferior MI in 80% of patients, and falsely indicating presence of MI in only 5% of normal subjects.     

Early left ventricular dysfunction in acute myocardial infarct. Evaluation using imaging methods

A patient admitted in a Coronary Care Unit with an acute anterior myocardial infarction, is presented. He had initially normal left ventricular function and, on the 11th day he had, suddenly, an acute pulmonary edema. The reason for this episode was detected through imaging techniques--echocardiography and isotopic studies, and consisted on infarct expansion with early evolution for apical aneurysm. Contrast angiography confirmed the presence of a huge aneurysm and two vessels disease. Tallium Scintigraphy showed reversible ischemia beyond necrotic areas. The patient was submitted to aneurysmectomy and received three aorto-coronary bypass. He is now doing well, in class I, NYHA. The discussion emphasizes the actual role of imaging techniques in the diagnosis of infarct expansion and early functional aneurysm. We discuss the prognostic of infarct expansion and the importance of perfusion studies on defining areas of myocardium in jeopardy, enabling a better surgical approach.     

Echoventriculography in acute myocardial infarction. IV. Infarct size and reliability by pathologic anatomic correlations

A morphologic–echocardiographic comparison was carried out in 24 consecutive patients to determine the accuracy of multidirectional single-beam echocardiography in imaging the size and site of 22 fatal acute myocardial infarctions and of 2 postinfarction ventricular aneurysms treated surgically. Echocardiography never missed the infarction, regardless of whether the infarction was anterior or posterior. The correlation between the echocardiographic and pathologic anatomic extent of infarct, as expressed by a percentage of the left ventricular horizontal circumference, was r = 0.88 (p<0.001). One hundred four of one hundred eleven infarcted segments (94%) were detected by echo; only the posterior septal and the most lateral segments of the left ventricle tended to remain out of range of the method. The regional asynergy at the center of the infarcted region was clear-cut—systolic thickening was never seen and the systolic wall motion was paradoxical in 75% of the patients (mean, ?2.0±2.0 mm). Analysis of the regional function from multiple sites characterized reduction of the left ventricular performance (p<0.0005) better than did the ejection fraction in the presence of asynergy. An old postinfarction scar was differentiated from the acute necrosis. Thus, segmental left ventricular akinesis or paradoxical motion as seen by multidirectional echocardiography permits noninvasively a reliable estimation of the extent of acute myocardial infarction.     

Comparison of enzymatic, anatomic and electrocardiographic estimates of myocardial infarct size in man

Myocardial infarct size is definitely related to cardiac function and prognosis. For a critical evaluation of infarct size estimation methods, we weighed infarcted myocardium from 44 autopsy cases (24 men and 20 women, mean age of 76.8 yr.), and compared the weight with the peak value of serum CPK activity (peak-CPK), the peak value of serum CPKMB isoenzyme activity (peak-CPKMB), the total CPK release (sigma CPK), and the QRS scoring system in the standard 12-lead electrocardiogram (ECG) modified by Wagner et al.. The mean infarcted myocardial weight (MI weight) of the 44 cases was 38.4 g. The mean value of the peak-CPK, peak-CPKMB, and sigma CPK were 2487, 221, and 4597 IU/ml, respectively, and the mean QRS point score was 7.2. The interval between serial CPK determination and ECG recording or autopsy averaged 130.1 or 52.4 days, respectively. There were significant (p less than 0.01) correlations between the MI weight and peak-CPK (r = 0.63, n = 17), peak-CPKMB (r = 0.79, n = 17), sigma CPK (r = 0.72, n = 11), and the QRS scoring system (r = 0.64, n = 39), respectively. Especially in cases of non-transmural myocardial infarction, the QRS scoring system showed a high correlation with MI weight (r = 0.82, n = 11, p less than 0.01). We conclude that the peak-CPK, peak-CPKMB, sigma CPK, and the QRS scoring system are useful for the estimation of myocardial infarct size.