Use of the QRS scoring system in the early estimation of myocardial infarct size following reperfusion

Prediction of improvement in left ventricular function during a 1-year follow-up after acute myocardial infarction by the degree of acute resolution of electrocardiographic changes

BACKGROUND AND PURPOSE

Reperfusion therapy results in better left ventricle (LV) function in cases of successful myocardial reperfusion; however, insufficient reperfusion or reocclusion of the infarct-related artery is associated with LV dysfunction. This study was proposed to determine whether the rate of ECG stage dynamics, after mechanical, thrombolytic, or spontaneous recanalization, is a predictor of improvement in LV function.

METHODS

Twenty-seven consecutive patients, observed for 1 year, were divided into group A (11, change rate of > or =2 ECG stages per 2 days), group B (13, no rapid change), and cases with reocclusion (3).

RESULTS

Clinical and radiographic signs of heart failure tended to decrease in group A but tended to increase in other cases. Echocardiographic dyssynergic score decreased, and LV ejection fraction increased only in group A: 4.3 +/- 1.2 vs 2.7 +/- 1.5, P = .04, and 42.0 +/- 4.8 vs 46.0 +/- 8.3, P = .049, respectively; in group B, the values were 3.4 +/- 2.4 vs 3.4 +/- 2.2 and 44.0 +/- 6.9 vs 43.8 +/- 9.3, respectively.

CONCLUSIONS

Rapid ECG stage changes predict follow-up improvement in LV function.

Size and transmural extent of first-time reperfused myocardial infarction assessed by cardiac magnetic resonance can be estimated by 12-lead electrocardiogram

BACKGROUND

The ability of the 12-lead electrocardiogram (ECG) to quantify size and transmural extent of myocardial infarction (MI) is not fully explored. Q waves are still thought of as indicative of transmural MI despite that several studies have rejected this association. We hypothesized that size and transmural extent of acute MI indeed can be estimated by QRS scoring on the 12-lead ECG using delayed, contrast-enhanced magnetic resonance imaging (DE-MRI) as gold standard and that Q waves are not predictive of transmural MI.

METHODS

Twenty-nine patients with first-time reperfused MI were studied. Delayed, contrast-enhanced magnetic resonance imaging was performed and 12-lead ECG was recorded 8 +/- 1 days after the acute event. Myocardial infarction size and transmurality were determined by DE-MRI and compared with Selvester QRS score from the ECG recorded on the same day.

RESULTS

There was a good correlation (r = 0.79, P < .001) between MI size by QRS scoring and DE-MRI. As local MI transmurality increased as assessed by DE-MRI, the local QRS score increased progressively (P < .001). There was no significant difference in the number of Q-wave-related QRS points between nontransmural and transmural MI (1.8 +/- 0.6 vs 2.9 +/- 0.4, P = .14). The global QRS score, however, differed significantly (3.1 +/- 0.8 vs 5.1 +/- 0.6, P < .05).

CONCLUSION

QRS score is significantly related to both MI size and transmurality by DE-MRI in patients with first-time reperfused MI. Presence of Q waves, however, is not indicative of transmural MI in these patients. Thus, QRS scoring could potentially be used for diagnosing and characterizing MI in patients with suspected recent MI.

Electrocardiographic infarct size assessment after thrombolysis: insights from the Acute Myocardial Infarction STudy ADenosine (AMISTAD) trial

BACKGROUND

Noninvasive methods are needed to evaluate reperfusion success in patients with acute myocardial infarction (MI). The AMISTAD trial was analyzed to compare MI size and myocardial salvage determined by electrocardiogram (ECG) with technetium Tc 99m sestamibi single-photon emission computerized tomography (SPECT) imaging.

METHODS

Of 236 patients enrolled in AMISTAD, 166 (70 %) with no ECG confounding factors and no prior MI were included in this analysis. Of these, group 1 (126 patients, 53%) had final infarct size (FIS) available by both ECG and SPECT. Group 2 (56 patients, 24%) had myocardium at risk, FIS, and salvage index (SI) assessed by both SPECT and ECG techniques. Aldrich/Clemmensen scores for myocardium at risk and the Selvester QRS score for final MI size were used. Salvage index was calculated as follows: SI = (myocardium at risk-FIS)/(myocardium at risk).

RESULTS

In group 1, FIS was 15% (6, 24) as measured by ECG and 11% (2, 27) as measured by SPECT. In the adenosine group, FIS was 12% (6, 21) and 11% (2, 22). In the placebo group, FIS was 16.5% (7.5, 24) and 11.5% (3.0, 38.5) by ECG and SPECT, respectively. The overall correlation between SPECT and ECG for FIS was 0.58 (P = .0001): 0.60 in the placebo group (P = .0001) and 0.54 (P = .0001) in the adenosine group. In group 2, myocardium at risk was 23% (17, 30) and 26% (10, 50) with ECG and SPECT, respectively (P = .0066). Final infarct size was 17% (6, 21) and 12% (1, 24) (P < .0001). The SI was 29% (-7, 57) and 46% (15, 79) with ECG and SPECT, respectively (P = .0510).

CONCLUSIONS

The ECG measurement of infarct size has a moderate relationship with SPECT infarct size measurements in the population with available assessments. This ECG algorithm must further be validated on clinical outcomes.

Prediction of decrease in myocardial perfusion defect size and severity during a 3-month follow-up by the degree of acute resolution of electrocardiographic changes

Myocardial perfusion in infarct-related artery (IRA) distribution improves progressively until a few months after successful reperfusion therapy. We assessed the rate of electrocardiographic (ECG) stage dynamics to predict perfusion improvement after mechanical, thrombolytic, or spontaneous recanalization of IRA. Thirteen patients were divided into group A (n = 8, with > or = 2 ECG stages per 2-day change rate) and group B (n = 5, no rapid change of ECG stages). There were no significant technetium Tc 99m sestamibi scintigraphic differences between the groups 3 days after recanalization; however, after 3 months, perfusion deficit size (2.8 +/- 1.8 vs 4.8 +/- 1.2, P < or = .03) and severity (1.8 +/- 0.9 vs 3.0 +/- 0, P < or = .03) were smaller in group A vs group B. The prediction sensitivity of the method was 87.5% for decrease in size and 100% for decrease in severity of perfusion defect; the specificity was 80% and 100%, respectively. A change rate of 2 or more ECG stages per 2 days predicts follow-up improvement of myocardial perfusion after IRA recanalization.

Prognostic value of predischarge electrocardiographic measurement of infarct size after thrombolysis: insights from GUSTO I Economics and Quality of Life substudy

BACKGROUND

Current methods for risk stratification after acute myocardial infarction (MI) include several noninvasive studies. In this cost-containment era, the development of low-cost means should be encouraged. We assessed the ability of an electrocardiogram (ECG) MI-sizing score to predict outcomes in patients enrolled in the Economics and Quality of Life (EQOL) sub study of the Global Utilization of Streptokinase and Tissue plasminogen activator for Occluded coronary arteries -I (GUSTO-I) trial.

METHODS

We classified patients by electrocardiographic Selvester QRS score at hospital discharge: those with a score 0-9 versus > or =10. Endpoints were 30-day and 1-year mortality, resource use, and quality-of-life measures.

RESULTS

Patients with a QRS score <10 were well-matched with those with QRS score > or =10 with the exception of a trend to more anterior MI in the higher scored group. Patients with QRS score > or =10 had increased risk of death at 30-days (8.9% vs. 2.9% P < .001), and this difference persisted at 1 year (12.6% vs. 5.4%, P = .001). Recurrent chest pain, use of angiography, and angioplasty were similar during follow-up. However, there was a trend toward less coronary bypass surgery in patients with a QRS score > or =10. Readmission rates were higher at 30 days but similar at 1 year.

CONCLUSIONS

Stratification of patients after acute MI by a simple measure of MI size identifies populations with different long-term prognoses; patients with a QRS score > or =10 (approximately 30% of the left ventricle infarcted) at discharge have poorer outcomes in both the short- and long-term. The standard 12-lead ECG provides a simple, economical means of risk stratification at discharge.

Aborted myocardial infarction in patients with ST-segment elevation

OBJECTIVES

The investigators undertook a systematic, comprehensive analysis of the therapeutic response and clinical outcomes of reperfusion therapy for acute ST-segment elevation myocardial infarction (STEMI) in 5,470 patients from the Assessment of the Safety and Efficacy of a New Thrombolytic Regimen (ASSENT)-3 trial.

BACKGROUND

Prompt effective reperfusion therapy for acute STEMI may attenuate major myocardial necrosis.

METHODS

We prospectively collected sequential electrocardiographs and clinical data. Aborted myocardial infarction (MI) was defined as maximal creatine kinase < or =2x upper limit of normal coupled with typical evolutionary electrocardiographic changes.

RESULTS

Of the patients, 727 (13.3%) had an aborted MI, with the highest frequency (25%) occurring in patients treated <1 h after symptom onset. As compared with MI patients, patients with aborted MI more often had complete ST-segment resolution at 60 min (56.3% vs. 30.2%, p < 0.001) and 180 min (61.5% vs. 53%, p < 0.001); they also had smaller infarct sizes based on QRS score at discharge (2.37 vs. 4.62, p <0.001). Mortality in aborted MI patients compared with those who had true MI was 3.9% versus 4.6% at 30-day and 7.0% versus 7.4% at 1-year. The baseline-adjusted mortality was significantly lower in patients with aborted MI (odds ratio [OR] 0.76, 95% confidence interval [CI] 0.63 to 0.92, p = 0.005 for 30-day and OR 0.70, 95% CI 0.50 to 0.98, p = 0.035 for one year). A very low-risk subset was identified with > or =70% ST-segment resolution at 60 min whose 30-day and 1-year mortality was 1.0% and 2.7%, respectively, compared with 5.9% and 9.3% in aborted MI patients with <70% ST-segment resolution at 60 min (all p < or = 0.002).

CONCLUSIONS

Prompt fibrinolytic treatment improved the likelihood of aborted MI. The subgroup with complete 60-min ST-segment resolution had the best clinical outcomes.

The predischarge electrocardiographic pattern in anterior acute myocardial infarction: relation between evolutionary ST segment and T-wave configuration and prediction of myocardial infarct size and left ventricular systolic function by the QRS Selvester score

Left ventricular systolic function, determined mainly by final infarct size, has a major influence on prognosis after acute myocardial infarction (MI). It was found that infarct size and left ventricular ejection fraction can be predicted using the Selvester QRS-score in patients not receiving reperfusion therapy. We assessed whether the predischarge QRS-score can be used for estimating infarct size and left ventricular ejection fraction in 51 patients with a first anterior MI who had received reperfusion therapy and whether considering the configuration of the ST-segments and T-waves will increase the accuracy of these predictions. All patients had received reperfusion therapy and had predischarge resting 99mTc-sestamibi scan. We determined the Selvester QRS score using the electrocardiograms performed on the same day of the scan. In addition, we divided the patients into 3 groups: A: isoelectric ST and negative T-waves (n = 12); B: ST elevation (> or =0.1 mV) and negative T-waves (n = 23); and C: ST elevation (> or =0.1 mV) and positive T-waves (n = 16). The myocardial perfusion defect extent increased from group A to C (28.5+/-16.4%, 39.4+/-14.8%, and 45.3+/-15.8% in groups A, B, and C. respectively; P = .022). Similarly, the left ventricular ejection fraction decreased (41.7+/-11.6%, 38.4+/-8.1%, and 32.0+/-9.7%, respectively; P = .042) from group A to C. Overall, the correlation between the QRS-score and the myocardial perfusion defect extent (Rho = 0.249; P = .08), and ejection fraction (Rho = -0.229; P = .11) was not good. A statistically significant correlation between the myocardial perfusion defect size and the QRS-score was found only in group A (Rho = 0.599, P = .04). In patients with a first anterior myocardial infarction who underwent reperfusion therapy, the predischarge QRS-score is predictive of infarct size only in those in whom ST elevation resolved completely. In patients with residual ST elevation the Selvester QRS-score is inaccurate in predicting infarct size and left ventricular ejection fraction upon discharge.

Dynamic changes of QT interval and QT dispersion in non-Q-wave and Q-wave myocardial infarction

QT interval and QT dispersion both prolong early postinfarction. Non-Q wave (NQMI) and Q-wave myocardial infarction (QMI) differ in the extent of transmural necrosis, which may influence these measures of myocardial repolarization. This study compared dynamic changes in QT interval and QT dispersion early postinfarction between NQMI and QMI. In 40 patients with NQMI and 69 patients with QMI, maximum QTc (QTc(max)) and QT dispersion (QTD) were measured during the first 4 days postinfarction. Infarct size was assessed daily by using the Selvester QRS score. In both infarct types, QTc(max) and QTD were prolonged on day 1 of infarction, peaking over the next 2 days before returning toward baseline by day 4. NQMI patients had significantly longer QTc(max) and QTD by days 2 to 3 when compared with QMI patients. Multivariable linear regression identified "infarct type x QRS score" as the only independent predictor of QTc(max) (R(2) =.32, P <.0001) and QTD (R(2) =.19, P <.0001) on day 2. In conclusion, dynamic changes of QTc(max) and QTD occur in both infarct types. Large NQMI is associated with greater prolongation of QTc(max) and QTD, which may be due to greater M cell uncoupling and exposure when compared with QMI.

Computer applications in the interpretation of the exercise electrocardiogram

The exercise electrocardiogram remains the noninvasive diagnostic test of first choice in patients with coronary artery disease. While new technology offers novel diagnostic possibilities and the ability to assess patients unsuitable for exercise testing, no other investigation has to this point furnished the quality of functional information and value-for-predictive accuracy of exercise electrocardiography. In this article, we describe how this central position in the work up of the cardiac patient has been secured through the evolution of the microprocessor. Particularly important has been its ability to harness and present large volumes of raw data, to derive and manipulate multivariate equations for diagnostic prediction, and to run 'expert' systems which can pool demographic and exercise test data, calculate risk scores, and prompt the nonexpert with advice on current management. These key features explain the pivotal role of the exercise test in the diagnostic, and increasingly prognostic, armoury of the cardiovascular clinician.

Relation between evolutionary ST segment and T-wave direction and electrocardiographic prediction of mycardial infarct size and left ventricular function among patients with anterior wall Q-wave acute myocardial infarction who received reperfusion therapy

In the prethrombolytic era it was found that infarct size and left ventricular ejection fraction could be predicted using the Selvester QRS score. We evaluated whether infarct size and left ventricular ejection fraction could be predicted by the predischarge QRS score in patients who had received reperfusion therapy and whether considering the configuration of the ST segments and T waves would increase the accuracy of these predictions. We evaluated 51 patients with first anterior wall myocardial infarction who had received reperfusion therapy and predischarge resting technetium-99m-sestamibi scan. The electrocardiograms recorded on the same day of the scan were analyzed for the QRS score and were divided into 3 groups: A, isoelectric ST and negative T waves; B, ST elevation (> or =0.1 mV) and negative T waves; and C, ST elevation (> or =0.1 mV) and positive T waves. Groups A, B, and C included 12, 23, and 16 patients, respectively. The myocardial perfusion defect extent increased from groups A to C (median 21%, 37%, and 43.5% in groups A, B, and C, respectively; p = 0.023). Similarly, left ventricular ejection fraction decreased (44%, 38%, and 34%, respectively; p = 0.042) from groups A to C. Overall, the correlation between the QRS score and the myocardial perfusion defect extent (rho 0.249; p = 0.08) and ejection fraction (rho -0.229; p = 0.11) was poor. A statistically significant correlation between myocardial perfusion defect size and QRS score was found only in group A (rho 0.599, p = 0.04). Among patients with anterior myocardial infarction who received reperfusion therapy, the predischarge QRS score was predictive of infarct size only in those in whom ST elevation resolved completely. In patients with residual ST elevation there was no correlation between QRS score and infarct size.