Relation between electrocardiographic and enzymatic methods of estimating acute myocardial infarct size

Complete versus simplified Selvester QRS score for infarct severity assessment in ST-elevation myocardial infarction

Background

Complete and simplified Selvester QRS score have been proposed as valuable clinical tool for estimating myocardial damage in patients with ST-elevation myocardial infarction (STEMI). We sought to comprehensively compare both scoring systems for the prediction of myocardial and microvascular injury assessed by cardiac magnetic resonance (CMR) imaging in patients with acute STEMI.

Methods

In this prospective observational study, 201 revascularized STEMI patients were included. Electrocardiography was conducted at a median of 2 (interquartile range 1–4) days after the index event to evaluate the complete and simplified QRS scores. CMR was performed within 1 week and 4 months thereafter to determine acute and chronic infarct size (IS) as well as microvascular obstruction (MVO).

Results

Complete and simplified QRS score showed comparable predictive value for acute (area under the curve (AUC) = 0.64 vs. 0.67) and chronic IS (AUC = 0.63 vs. 0.68) as well as for MVO (AUC = 0.64 vs. 0.66). Peak high sensitivity cardiac troponin T (hs-cTnT) showed an AUC of 0.88 for acute IS and 0.91 for chronic IS, respectively. For the prediction of MVO, peak hs-cTnT represented an AUC of 0.81.

Conclusions

In reperfused STEMI, complete and simplified QRS score displayed comparable value for the prediction of acute and chronic myocardial as well as microvascular damage. However, both QRS scoring systems provided inferior predictive validity, compared to peak hs-cTnT, the clinical reference method for IS estimation.

Predictive value of cardiac troponin-I compared to creatine kinase-myocardial band for the assessment of infarct size as measured by cardiac magnetic resonance

BACKGROUND

The estimation of infarct size by biochemical myocardial necrosis markers is used in current clinical practice, rather than the more expensive and not always available imaging techniques. However, for this purpose, the peak value of serum biomarkers can overestimate the necrotic area, especially after reperfusion.

OBJECTIVE

We investigated whether late release cardiac troponin I (cTnI) values could predict more precisely infarct volume measured by delayed-enhancement cardiac magnetic resonance (DE-CMR) in patients with acute myocardial infarction [ST-elevation myocardial infarction (STEMI) and non-STEMI (NSTEMI)] independently of reperfusion (spontaneous and provoked).

METHODS

Sixty patients with a first acute myocardial infarction (55 STEMI and five NSTEMI) and normal function were enrolled. Among STEMI patients, 52 underwent reperfusion. cTnI and creatine kinase-myocardial band were assessed at admission and at 6, 12, 24, 48, 72 and 96 h (+/-1 h) from symptom onset. DE-CMR (Siemens Avanto 1.5T) was performed before discharge (4 +/- 2 days). Infarct size was determined by manual delineation of the areas of delayed enhancement. Infarct volume was calculated as the sum of each slice of infarct size area multiplied by thickness.

RESULTS

Peak cTnI was 55 +/- 59 ng/ml (range 0.3-347). The area under the curve of cTnI was 1916 +/- 2224 ng/ml. The volume of infarcted myocardium assessed by DE-CMR was 27 +/- 25 ml (range 0-134). The single value of cTnI at 72 h after symptom onset provided the most accurate estimation of predischarge infarct volume (r = 0.84, 95% confidence interval 0.75-0.91) and was significantly more accurate than creatine kinase-myocardial band value assessed at any time during the same period (r = 0.42, 95% confidence interval 0.19-0.62; P < 0.002).

CONCLUSION

In patients with a first acute myocardial infarction, cTnI value assessed at 72 h from symptom onset shows the best correlation with predischarge infarct volume as assessed by DE-CMR and is superior to cTnI and creatine kinase-myocardial band peak and total values.

Usefulness of the QRS score as a strong prognostic marker in patients discharged after undergoing primary percutaneous coronary intervention for ST-segment elevation myocardial infarction

The prognostic value of myocardial infarct size estimation by QRS scoring in patients with ST-segment elevation myocardial infarction (STEMI) who undergo primary percutaneous coronary intervention (PCI) is unclear. The standard 32-point Selvester QRS score on the discharge electrocardiogram (each point approximately 3% left ventricular mass) was calculated in 4,113 patients with STEMI who underwent primary PCI and survived to hospital discharge in the APEX-AMI trial. QRS scores were divided into tertiles, i.e., < or =3 (<10% myocardium), 4 to 7 (10% to 21% myocardium), and > or =8 (>21% myocardium). Adjusted associations between QRS score and 90-day outcomes (death and composite of death/congestive heart failure (CHF)/shock) were examined. Higher QRS scores were associated with male gender, higher heart rate, worse Killip class, noninferior infarct location, greater ST-segment deviation, and longer times to reperfusion. Higher QRS scores were also associated with impaired culprit artery flow before and after PCI and more frequent multivessel disease. Adverse outcomes occurred more often in patients with higher QRS scores (90-day death: 1.9%, QRS score 0 to 3; 3.4%, 4 to 7; 4.9%, > or =8; 90-day death/shock/CHF: 4.5%, 0-3; 7.8%, 4 to 7; 12.1%, > or =8). After multivariable adjustment, patients with higher QRS scores remained more likely to develop an adverse outcome versus those with QRS scores < or =3 (score 4 to 7, hazard ratios [HR] for death 2.08, 95% confidence interval [CI] 1.26 to 3.41; HR for death/CHF/shock 2.00, 95% CI 1.26 to 3.17; score > or =8, HR for death 2.57, 95% CI 1.56 to 4.24, HR for death/CHF/shock 2.93, 95% CI 1.84 to 4.67). In conclusion, infarct size as estimated by QRS scoring at hospital discharge is an independent and prognostically relevant metric in patients with STEMI undergoing primary PCI.

Estimation of infarct size by single measurements of creatine kinase levels in patients with a first myocardial infarction

OBJECTIVE

Enzymatic estimation of infarct size is desirable in the reperfusion era, because a possible discrepancy with the observed asynergic area of the left ventricle may suggest the presence of stunned myocardium. Unfortunately, timely myocardial reperfusion produces a rapid washout of creatine kinase (CK) in blood flow, which overestimates infarct size. In this perspective, we investigated whether the mid-terminal portion of the CK time-activity curve could predict infarct size more reliably.

METHODS

Enzymatic infarct size was calculated by peak CK levels, the CK area under the curve and by single CK values, in 103 patients with a first ST-elevation myocardial infarction, and compared to the left ventricular akinetic area. The wall motion asynergy score at follow-up was considered as the actual infarct size.

RESULTS

In patients with peak CK within 10 h of symptom onset, CK levels at 30 h showed a high independent correlation (r = 0.83; P < 0.001) with infarct size. In patients with late peak CK (> 10 h), CK levels at 12 h turned out to be the best predictor of infarct size (r = 0.55; P < 0.01). At multivariate regression analysis, peak CK was the best predictor of infarct size in the whole population (r = 0.61; P < 0.001).

CONCLUSIONS

In patients with ST-elevation myocardial infarction and early peak CK, infarct size at follow-up could be better estimated with single values of the mid-terminal portion of the CK time-activity curve.

Enzyme estimates of infarct size correlate with functional and clinical outcomes in the setting of ST-segment elevation myocardial infarction

Background

Cardiac biomarkers are routinely obtained in the setting of suspected myocardial ischemia and infarction. Evidence suggests these markers may correlate with functional and clinical outcomes, but the strength of this correlation is unclear. The relationship between enzyme measures of myocardial necrosis and left ventricular performance and adverse clinical outcomes were explored.

Methods

Creatine kinase (CK) and CK-MB data were analyzed, as were left ventricular ejection fraction (LVEF) by angiogram, and infarct size by single-photon emission computed tomography (SPECT) imaging in patients in 2 trials: Prompt Reperfusion In Myocardial-infarction Evolution (PRIME), and Efegatran and Streptokinase to Canalize Arteries Like Accelerated Tissue plasminogen activator (ESCALAT). Both trials evaluated efegatran combined with thrombolysis for treating acute ST-segment elevation myocardial infarction (STEMI).

Results

Peak CK and CK area-under-the-curve (AUC) correlated significantly with SPECT-determined infarct size 5 to 10 days after enrollment. Peak CK had a statistically significant correlation with LVEF, but CK-AUC and LVEF correlation were less robust. Statistically significant correlations exist between SPECT-determined infarct size and peak CK-MB and CK-MB AUC. However, there was no correlation with LVEF for peak CK-MB and CK-MB AUC. The combined outcome of congestive heart failure and death were significantly associated with CK AUC, CK-MB AUC, peak CK, and peak CK-MB measurements.

Conclusion

Peak CK and CK-MB values and AUC calculations have significant correlation with functional outcomes (LVEF- and SPECT-determined infarct size) and death or CHF outcomes in the setting of STEMI. Cardiac biomarkers provide prognostic information and may serve as valid endpoint measurements for phase II clinical trials.

Electrocardiographic prediction of the severity of posterior wall perfusion defects on rest technetium-99m Sestamibi myocardial perfusion imaging

To identify electrocardiogram (ECG) variables predicting the severity of previous posterior wall myocardial infarction as measured by technetium-99m-Sestamibi rest single-photon emission computed tomography, we assessed agreement between ECG criteria and posterior wall perfusion defects (PWPDs) in 236 patients. Established ECG criteria for posterior and posterolateral infarctions were present in 22% and 19% of patients, respectively, and did not predict severity of PWPD ( P = NS). Univariate predictors of severity were the Selvester QRS score (SQS) ( P = .001) and an upright T wave in V 1 (UTV 1 ) greater than 0.2 mV ( P = .001). Regression analysis demonstrated that SQS ( P = .0001) and UTV 1 greater than 0.2 mV ( P = .006) were highly predictive of severity ( c statistic = 0.793). All severe PWPDs had an SQS of 2 or higher. Established ECG patterns for diagnosis of posterior infarction are insensitive and poor predictors of severity. The SQS and UTV 1 are effective for the diagnosis of posterior infarction and useful for the estimation of infarct severity.

Autologous bone marrow-derived progenitor cell transplantation for myocardial regeneration after acute infarction

Background. Experimental and first clinical studies suggest that the transplantation of bone marrow derived, or circulating blood progenitor cells, may beneficially affect postinfarction remodelling processes after acute myocardial infarction. Aim. This pilot trial reports investigation of safety and feasibility of autologous bone marrow-derived progenitor cell therapy for faster regeneration of the myocardium after infarction. Methods and results. Four male patients (age range 47-68 years) with the first extensive anterior, ST elevation, acute myocardial infarction (AMI), were treated by primary angioplasty. Bone marrow mononuclear cells were administered by intracoronary infusion 3-5 days after the infarction. Bone marrow was harvested by multiple aspirations from posterior cristae iliacae under general anesthesia, and under aseptic conditions. After that, cells were filtered through stainless steel mesh, centrifuged and resuspended in serum-free culture medium, and 3 hours later infused through the catheter into the infarct-related artery in 8 equal boluses of 20 ml. Myocardial viability in the infarcted area was confirmed by dobutamin stress echocardiography testing and single-photon emission computed tomography (SPECT) 10-14 days after infarction. One patient had early stent thrombosis immediately before cell transplantation, and was treated successfully with second angioplasty. Single average ECG revealed one positive finding at discharge, and 24-hour Holter ECG showed only isolated ventricular ectopic beats during the follow-up period. Early findings in two patients showed significant improvement of left ventricular systolic function 3 months after the infarction. There were no major cardiac events after the transplantation during further follow-up period (30-120 days after infarction). Control SPECT for the detection of ischemia showed significant improvement in myocardial perfusion in two patients 4 months after the infarction. Echocardiographic assessment in these two patients also showed significant improvement of systolic function three months after the infarction. Conclusion. Preliminary results of the study showed that the transplantation of bone marrow-derived progenitor cells into the infarcted area was safe, and feasible, and might improve myocardial function. Further follow-up will show if this treatment is effective in preventing negative remodeling of the left ventricle and reveal potential late adverse events (arrhythmogenicity and propensity for restenosis).

Terminal QRS distortion on admission is better than ST-segment measurements in predicting final infarct size and assessing the Potential effect of thrombolytic therapy in anterior wall acute myocardial infarction

We assessed predicting final infarct size (using predischarge Selvester score) by 3 electrocardiographic variables in 267 patients with first anterior wall acute myocardial infarction (AMI) undergoing (n = 86) or not undergoing (n = 181) thrombolysis. Patients with previous AMI or inverted T waves in leads with ST elevation were excluded. The sum (sigma) of ST elevation, the number of leads with ST elevation, and the initial electrocardiographic pattern were determined on the admission electrocardiogram (absence (QRS-) or presence (QRS+) of distortion of the terminal portion of the QRS in > or =2 leads (J point > or =0.5 of the R-wave amplitude in leads I, aVL, V4 to V6, or presence of ST elevation without S waves in leads V1 to V3). There was no association between sigmaST elevation and final infarct size in patients who did or did not receive thrombolytic therapy. Analysis of covariance showed that the number of leads with ST elevation (F = 19.6), thrombolysis (F = 25.2), and QRS+ initial pattern (F = 19.5) were all associated with final infarct size (p <0.0001 for all). Among patients who did not receive thrombolytic therapy, the average Selvester score was 19.7+/-9.9 for the QRS- patients and 26.1+/-10.4 for the QRS+ patients (p = 0.02). Among patients who received thrombolytic therapy, the average Selvester score was 11.7+/-9.8 for the QRS- patients and 24.2+/-10.1 for the QRS+ patients (p <0.0001). Thrombolysis reduced final Selvester score only in the QRS- group (p <0.00001), but not in the QRS+ group (p = 0.45). It is concluded that (1) final Selvester score in anterior wall AMI can be predicted by the number of leads with ST elevation, the initial electrocardiographic pattern, and thrombolysis, and (2) thrombolysis reduces final Selvester score only in patients with QRS- pattern.

An open label, randomised, crossover study comparing sotalol and atenolol in the treatment of symptomatic paroxysmal atrial fibrillation

OBJECTIVE

To compare sotalol and atenolol in the treatment of symptomatic paroxysmal atrial fibrillation.

DESIGN

Prospective, randomised, open label, crossover study.

SETTING

University hospital.

PATIENTS

47 subjects aged over 50 years were recruited from the hospital outpatient department following ECG documentation of paroxysmal atrial fibrillation that coincided with symptoms. Six patients withdrew and 41 completed the trial.

INTERVENTIONS

Patients were randomised to one month's treatment with sotalol 80 mg twice daily or atenolol 50 mg once daily. Treatment arms were then crossed over. Patients underwent 72 hour Holter monitoring before randomisation and repeat studies were carried out at the end of both treatment periods. Symptom assessments were completed using linear analogue scales and the Nottingham health profile.

MAIN OUTCOME MEASURE

Frequency of paroxysmal atrial fibrillation; secondary outcome measures included average and total duration of paroxysmal atrial fibrillation, total ectopic count, and symptom assessments.

RESULTS

A reduction in the number and duration of episodes of paroxysmal atrial fibrillation was noted following treatment with sotalol and atenolol. There was no difference in frequency of paroxysmal atrial fibrillation during treatment with sotalol or atenolol (median difference 0; 95% confidence interval (CI) 0 to 1; p = 0.47). There was no difference in total duration of paroxysmal atrial fibrillation (median difference 0 min; 95% CI -1 to 2; p = 0. 51) or in average duration (median difference 0 min; 95% CI 0 to 1; p = 0.31). No difference was found in total ectopic count between sotalol and atenolol (median difference -123; 95% CI -362 to 135; p = 0.14). Treatments were equally tolerated with no difference in linear analogue scores for symptoms of paroxysmal atrial fibrillation (median difference -5; 95% CI -20 to 5; p = 0.26) or in all categories of the Nottingham health profile.

CONCLUSIONS

No difference was found in terms of ECG or symptomatic control of paroxysmal atrial fibrillation between prescribing sotalol 80 mg twice daily and atenolol 50 mg once daily. There was an improvement in paroxysmal atrial fibrillation from baseline following treatment with either sotalol or atenolol.

Comparison of the various electrocardiographic scoring codes for estimating anatomically documented sizes of single and multiple infarcts of the left ventricle

It is clinically important to estimate the size of a myocardial infarction (MI) to predict patient prognosis, to determine the ability of a therapy to limit its size, and to evaluate its effect on left ventricular function. Various electrocardiographic methods have been used for these purposes but their accuracies have not been compared with each other using an identical reference population of anatomically measured infarcts. The capability of 4 electrocardiographic scoring methods (the Selvester score, the Minnesota code, the Novacode, and the Cardiac Infarction Injury Score) to estimate MI size was compared using anatomic MI size in a group of 100 deceased patients. All patients had a standard 12-lead electrocardiogram of sufficient quality to perform manual waveform measurements and without confounding factors such as ventricular hypertrophy, fascicular block, or bundle branch block. The location and size of the left ventricular infarction was measured postmortem using the anatomic method of Ideker et al. All methods' size estimates correlated best with anatomic MI size in the anterior location (r = 0.65 to 0.89). The Selvester score was superior in estimating the sizes of inferior (r = 0.70) and posterolateral (r = 0.74) infarcts. For multiple infarcts all methods performed poorly (r = 0.18 to 0.44).

Sum of ST-segment elevations on admission electrocardiograms in acute myocardial infarction predicts left ventricular dilation

In summary, ST-segment elevations on the admission electrocardiogram not only diagnose acute myocardial infarction but also provide predictive information with respect to developing infarct size and left ventricular remodeling as well as survival.

Early spontaneous intermittent myocardial reperfusion during acute myocardial infarction is associated with augmented thrombogenic activity and less myocardial damage

OBJECTIVES

This study investigated the influence of early spontaneous intermittent reperfusion on the extent of myocardial damage and its relation to endogenous hemostatic activity.

BACKGROUND

In the early phase of acute myocardial infarction coronary occlusion is often intermittent, even before thrombolytic therapy is administered. The relation between this phenomenon, myocardial damage and hemostatic activity is unknown.

METHODS

Holter ST segment recording and pretreatment plasma tissue-type plasminogen activator (t-PA) antigen, plasminogen activator inhibitor-1 (PAI-1) antigen, prothrombin fragment F1 + 2 and soluble fibrin levels were measured in 57 patients with acute evolving myocardial infarction. Spontaneous intermittent myocardial reperfusion, defined as two or more episodes of transient resolution of ST segment elevation to within 0.05 mV of baseline, lasting > or = 1 min, before the start of recombinant t-PA (rt-PA) treatment was present in 28 patients (group 1) and absent in 29 (group 2). Left ventriculography and coronary angiography were performed 90 min after intravenous rt-PA administration. Plasma creatine kinase-MB fraction (CK-MB) levels were measured every 6 h for 24 h, and C-reactive protein levels were measured daily for 3 days.

RESULTS

Group 1 had lower peak plasma CK-MB (141.9 +/- 28.3 vs. 203.8 +/- 23.3 IU/liter [mean +/- SEM], p < 0.014) and C-reactive protein levels (16 +/- 4 vs. 28 +/- 4 mg/liter on day 1; 26.6 +/- 5.5 vs. 61.8 +/- 14.4 mg/liter on day 2; 19.6 +/- 4.2 vs. 40.6 +/- 6.5 mg/liter on day 3, p < 0.012) and a higher left ventricular ejection fraction (62.9 +/- 4% vs. 51.1 +/- 5%, p < 0.04) than group 2. Group 1 had lower plasma t-PA antigen levels (15.6 vs. 27 micrograms/liter, p < 0.006) but higher prothrombin fragment F1 + 2 (1.8 vs. 1.1 nmol/liter, p < 0.003) and soluble fibrin levels (66.8 vs. 31 nmol/liter, p < 0.01). Coronary patency at 90 min was similar.

CONCLUSIONS

Early spontaneous intermittent reperfusion during acute myocardial infarction is associated with augmented thrombogenic activity and less subsequent myocardial damage. This finding is consistent with a protective effect of intermittency on the myocardium and a procoagulant effect of spontaneous lysis on blood. It may also reflect a different rate of evolution of coronary thrombosis and myocardial infarction in patients with and those without spontaneous intermittent myocardial reperfusion.

QRS score as an indicator of myocardial viability after thrombolytic therapy

Electrocardiographic estimation of myocardial injury has, in some studies, correlated poorly with the extent of nuclear perfusion defects at rest and with changes in the left ventricular ejection fraction after acute reperfusion therapy. The authors investigated 16 patients with fatty acid scintigraphy and with the Selvester-Wagner QRS score 2 weeks and 3 months after an anterior myocardial infarction. Segmental uptake on tomographic scans was semiquantitatively classified as low, moderate, or normal. The analysis included a total of 707 segments. QRS scores and the number of segments with low fatty acid uptake did not significantly change during the follow-up period, although the number of segments with moderate fatty acid uptake decreased from 15.9 +/- 5.1 to 12.4 +/- 5.7 (P < .05). The QRS score correlated significantly (rho = .56-.64) with low fatty acid uptake, but not with moderate fatty acid uptake. It is concluded that the QRS score is related to the degree of permanent myocardial injury, even after thrombolysis.

Estimation of anterior infarct size with body surface QRST integral maps in the presence of abnormal ventricular activation sequence in dogs

The possibility of estimating infarct size with body surface QRST integral (IQRST) maps was investigated in dogs. IQRST maps were constructed from 87-lead body surface ECGs, which were recorded 1 week after the production of anterior myocardial infarction during artificial pacing that simulated normal conduction, left bundle branch block, and Wolff-Parkinson-White syndrome in 11 dogs. Small differences were observed between the IQRST maps of the normal conduction and left bundle branch block models (r = 0.93, root mean square difference = 8.71 mVmsec) and between the normal conduction and Wolff-Parkinson-White models (r = 0.96, root mean square difference = 6.03 mVmsec). Summation of the QRST integral values over the body surface leads (QRST index) inversely correlated with infarct size in all three conductions models: r = 0.91 (p < 0.001) in the normal conduction model; r = -0.81 (p < 0.001) in the left bundle branch block model; and r = -0.86 (p < 0.001) in the Wolff-Parkinson-White model. These results show that IQRST maps permit noninvasive estimation of infarct size, even in the presence of abnormal activation sequences.

Intravenous atenolol in elderly patients in the early phase of acute myocardial infarction

The aim of this study was to assess the hemodynamic response to intravenous atenolol in elderly patients with acute myocardial infarction. We studied 14 elderly men, aged 64-85 years, and 14 younger men, aged 29-48 years, in the early postfibrinolytic phase of acute myocardial infarction. All the patients were in Killip class I. A triple-lumen Swan-Ganz thermodilution catheter was introduced into the right heart chambers. The patients received 5 mg intravenous atenolol over 5 minutes. All hemodynamic parameters were measured before and 10 minutes after atenolol. The hemodynamic characteristics and the location and extent of acute myocardial infarction were the same in both groups before atenolol. The hemodynamic changes after atenolol administration were the same in the two groups, but the stroke volume and cardiac indexes decreased to a greater extent in the elderly (p = .01 and p = .0001, respectively). These results indicate that intravenous atenolol in the early postfibrinolytic phase of acute myocardial infarction is safe in Killip class I elderly patients, although the cardiac and stroke volume indexes decrease, and the increase in the total systemic resistance is more in older than in younger patients.

QRS scoring with the Mason-Likar lead system at rest and during ischaemia

The stability of the post-infarction simplified 29-point Selvester QRS score during maximal exercise testing was studied using both standard 12 and Mason-Likar (modified standard, M-L) ECG lead systems. Thirty-eight patients participated in the standard exercise test (mean interval after single infarction 4 months) and a total of 54 patients underwent exercise 201thallium emission tomography with M-L lead system 2 months later. None had electrocardiographic features complicating the scoring. There were no significant differences between the (paired) mean QRS scores, except between the M-L score at rest (2.3 +/- 2.4) and at exercise (3.2 +/- 2.6, P less than 0.01). The correlation coefficient (r) between resting scores was 0.87, between rest and exercise 0.90 (standard leads) and 0.80 (M-L leads). In 78% nuclear imaging revealed ischaemia, but this had no significant effect on the mean scores or correlation between rest and exercise scores. It is concluded that the QRS score is relatively stable during exercise with standard leads if the limb leads are recorded immediately after the exercise. Scoring with the M-L lead system is somewhat inaccurate, especially during exercise, and is not recommended for stratification of clinical risk. The QRS score is protected against ischaemia, which emphasizes its value as an independent prognostic tool.

Prognostic use of a QRS scoring system after hospital discharge for initial acute myocardial infarction in the Framingham cohort

Myocardial infarct size is an important risk factor for survival after acute myocardial infarction (AMI). The purpose of this study was to determine the prognostic value of myocardial infarct size, as estimated by the Selvester 54-criteria/32-point QRS scoring system, in the Framingham cohort. During the first 30 years of the Framingham Heart Study, a total of 384 participants developed an AMI requiring hospitalization; from this group, 243 patients met the following inclusion criteria: (1) no electrocardiographic changes due to a previous infarction, (2) survival greater than 3 days after discharge from the AMI hospitalization and (3) no electrocardiographic evidence of conduction disturbances or ventricular hypertrophy at the time of their final in-hospital electrocardiogram. Univariate and multivariate analyses were performed to test the association of the QRS score, and other associated risk factors, with time until coronary heart disease-related death. QRS score was found to be significantly associated with outcome (p = 0.03), as was the systolic blood pressure before infarction (p greater than 0.001). Both univariate and multivariate analysis showed that a history of systolic hypertension was the variable most strongly associated with coronary heart disease-related death. Thus, identification of AMI survivors at high risk for subsequent mortality can be improved by routine blood pressure measurement before AMI, and QRS scoring of the electrocardiogram taken at hospital discharge.

The electrocardiographic diagnosis of acute myocardial infarction in the thrombolytic era

The 12-lead ECG remains a simple and inexpensive technique to diagnose AMI in its early phases. The diagnostic accuracy of the ECG depends upon the extent of myocardial necrosis and its localization. The ECG is most sensitive in patients with occlusion of the LAD artery, followed by the RCA and the left CFA. In 10% to 20% of patients with AMI the initial ECG either shows nonspecific changes or is normal. The correlation between the ECG and infarct-related artery varies according to the involved vessel. Classic ECG changes are seen in 90% of the LAD artery, in 70% to 80% of RCA, and in only 50% of CFA occlusions. A second important issue is the mechanism and clinical significance of reciprocal ST segment changes, which usually indicate larger MI, more impaired ventricular function, worse prognosis, and in some patients, significant disease of a noninfarct-related artery. Furthermore, the value of the ECG in estimating myocardial injury and infarct size remains controversial. The ECG plays an important role in coronary reperfusion. ST segment elevation is one of the principal criteria for instituting thrombolytic therapy, and helps predict those who will most likely benefit from coronary reperfusion. The role of the ECG in evaluating the reperfusion status after coronary thrombolysis is not clear. Rapid return to baseline or normalization of the ST segment suggests opening of the occluded vessel, though a small or negligible change does not exclude successful reperfusion.

Relationship of QRS scoring system to enzymatic and pathologic infarct size: the role of infarct location

A method for estimating infarct size from 12-lead ECGs has been developed but not extensively validated. To assess its accuracy, ECG scores from 62 patients admitted to the coronary care unit at Barnes Hospital were compared to infarct size calculated from plasma MB creatine kinase (MB-CK) activity. A second cohort of 29 patients enrolled in the Multicenter Investigation of the Limitation of Infarct Size (MILIS) was evaluated as a test set and to provide pathologic correlates. Patients with conduction system disease, ventricular hypertrophy, or multiple infarctions were excluded, as were those in the Barnes group who had undergone thrombolytic therapy. ECGs obtained early (days 3 to 7 in the Barnes group and day 3 in the MILIS group) or late (days 8 to 14 in the Barnes group) were scored manually and by computer. QRS scores from early ECGs of patients with anterior infarctions correlated closely with MB-CK estimates of infarct size (r = 0.71 [Barnes] and 0.85 [MILIS] and with anatomic data (r = 0.78). Enzymatic and pathologic infarct size also correlated well (r = 0.85). Correcting for body surface area by means of total CK-derived infarct size or use of QRS scores from late ECGs did not alter the correlation coefficients. Among patients with inferior infarctions QRS scores corresponded poorly with MB-CK infarct size (r = 0.28 [Barnes] and r = -0.42 [MILIS]) and pathologic infarct size (r = -0.20), despite a significant relationship between pathologic and MB-CK estimates (r = 0.62).(ABSTRACT TRUNCATED AT 250 WORDS)

Development and validation of an automated method of the Selvester QRS scoring system for myocardial infarct size

The Selvester QRS score for estimation of myocardial infarct (MI) size from the standard 12-lead electrocardiogram (ECG) has not yet achieved wide recognition as a valuable tool in the routine assessment of the MI patient, primarily because of the practical limitations inherent to manual application. This study examined the ECGs of 438 patients (105 normal subjects, 161 with "possible" MI and 172 with "definite" MI based on data from cardiac catheterization) to develop software for an automated method of the Selvester system in attempts to overcome the manual constraints. After a comprehensive validation process involving extensive interactions between the manual scorer and the software developer, an automated method of the Selvester system was generated that had a high correlation with manual application (r = 0.94) and was superior regarding time, training, reader bias, reproducibility and precision of measurement. These results indicate that an automated version of the Selvester QRS scoring system would resolve many of the limitations of manual application and would provide a reliable, technically accurate estimate of MI size that could be incorporated into ECG diagnostic programs and used in standard digital ECG machines.

Right ventricular infarction: frequency, size and topography in coronary heart disease: a prospective study comprising 107 consecutive autopsies from a coronary care unit

During a 14 month period autopsies were performed on 107 patients with coronary heart disease and the results were evaluated prospectively with special reference to right ventricular infarction. A total of 214 regional infarcts were found, 107 (50%) of which involved the right ventricle. Right ventricular infarction was found in 90 hearts (84%), but only three isolated right ventricular infarcts were seen. Right ventricular involvement was found with equal frequency in anterior and posterior infarction (64 versus 66%), but posterior right ventricular infarcts were much larger (15% of the right ventricle was infarcted versus 1%). Proximal right coronary artery occlusion caused larger right ventricular infarction than did distal occlusion (15 versus 5 g). Right ventricular infarct size was not influenced by coronary artery disease (evaluated angiographically) in noninfarct-related vessels. Anterior right ventricular infarcts were predominantly located near the apex of the heart (to the left of the sternum), whereas posterior right ventricular infarcts were located near the atrioventricular groove (along the right sternal border). Infarct size was equal in patients who died from a first acute anterior or posterior infarct. However, posterior infarcts had more right ventricular involvement (28% of total infarct size versus 7% in anterior infarcts) leaving more of the left ventricular myocardium intact (79 versus 64%). These differences in infarct topography may explain why right ventricular involvement seldom is diagnosed clinically in patients with anterior infarction, and why left ventricular function and prognosis usually are better after posterior compared with anterior infarcts of enzymatically equal size.

A comprehensive estimation of acute myocardial infarct size using enzymatic, electrocardiographic and mechanical methods

This prospective study compares the estimated size of acute myocardial infarction (AMI) by cumulative serum creatine kinase isoenzyme MB (CK-MB), Selvester QRS score, and 2-dimensional (2-D) echocardiographic dyssynergy of the left ventricle in 63 consecutive patients with their first anterior (n = 31) or inferior AMI (n = 32). The correlations among these parameters were good for patients with anterior AMI (r = 0.74 to 0.78, standard error of the estimate = 29 to 33%) but only fair for those with inferior AMI (r = 0.35 to 0.47, standard error of the estimate = 38 to 73%). Based on previous autopsy studies, estimates of CK-MB and QRS score were then converted to percent of infarcted left ventricle. Linear regression analyses between mean percent AMI size by cumulative CK-MB plus QRS score vs the number of dyssynergic segments by 2-D echocardiography were used to develop a comprehensive formula for estimating AMI size by a combination of all 3 techniques. Thus, a formula is proposed that may optimally estimate AMI size derived from leakage of cytosolic enzymes, changes in the sequence of myocardial depolarization, and irregularities of left ventricular contraction.

Enhancement of an old diagnostic tool, the standard 12-lead ECG

The standard 12-lead electrocardiogram (ECG) has long been a reliable clinical tool for diagnosis of myocardial infarction (MI). Minutes may be crucial in the decision regarding urgent interventions for the salvage of severely ischemic myocardium during an acute MI. Besides history and physical findings the ECG may be the only clinical tool immediately available in deciding to initiate acute coronary thrombolysis or balloon angioplasty. Most of the newer techniques are difficult to perform and time consuming, and thus are not immediately available. Recent studies have indicated that there may be important information revealed by the amplitude and direction of the ST-T vectors on the admission ECG that will correlate with the final infarct size which evolves during the next few hours. The Selvester QRS scoring system, based on computer simulations of the human heart activation sequence, uses quantitative information in the 12-lead ECG to estimate the size of an MI. This system, which can be automated, has been examined for specificity in a large database of normals, and validated in a series of comprehensive post-mortem studies, and in other clinical estimates of prognosis and MI size. The QRS scoring system is limited by its inability to differentiate between small MIs and normal myocardium and by the confounding effects on the ECG of ventricular hypertrophy, conduction defects, and multiple MIs. Current studies are expected to overcome most of these limitations. Computer technology further augments the clinical utility of the ECG by providing unique assessment of a patient from individualized demographic and historical characteristics.(ABSTRACT TRUNCATED AT 250 WORDS)