A QRS scoring system for assessing left ventricular function after myocardial infarction

Machine learning-based prediction of infarct size in patients with ST-segment elevation myocardial infarction: A multi-center study

BACKGROUND

Cardiac magnetic resonance imaging (CMR) is the gold standard for measuring infarct size (IS). However, this method is expensive and requires a specially trained technologist to administer. We therefore sought to quantify the IS using machine learning (ML) based analysis on clinical features, which is a convenient and cost-effective alternative to CMR.

METHODS AND RESULTS

We included 315 STEMI patients with CMR examined one week after morbidity in final analysis. After feature selection by XGBoost on fifty-six clinical features, we used five ML algorithms (random forest (RF), light gradient boosting decision machine, deep forest, deep neural network, and stacking) to predict IS with 26 (selected by XGBoost with information gain greater than average level of 56 features) and the top 10 features, during which 5-fold cross-validation were used to train and optimize models. We then evaluated the value of actual and ML-IS for the prediction of adverse remodeling. Our finding indicates that MLs outperform the linear regression in predicting IS. Specifically, the RF with five predictors identified by the exhaustive method performed better than linear regression (LR) with 10 indicators (R² of RF: 0.8; LR: 0). The finding also shows that both actual and ML-IS were independently associated with adverse remodeling. ML-IS ≥ 21% was associated with a twofold increase in the risk of LV remodeling (P < 0.01) compared with patients with reference IS (1st tertile).

CONCLUSION

ML-based methods can predict IS with widely available clinical features, which provide a proof-of-concept tool to quantitatively assess acute phase IS.

Original Article--Value of Pathological Q Waves and Angiographic Collateral Grade in Patients Undergoing Coronary Chronic Total Occlusion Recanalization: Cardiac Magnetic Resonance Study

Background/aim

Successful coronary chronic total occlusion (CTO) revascularization was found by many studies to be associated with improved left ventricular (LV) systolic function and survival if evidence of viability is present. Little is known about the association of CTO revascularization in patients with electrocardiographic Q waves and improvement in angina burden as a measurement of health-related quality of life (HRQOL) afterwards.

Methods

In this study, 100 patients with single vessel CTO were included. Myocardial viability was tested by late gadolinium enhancement (LGE) on cardiac magnetic resonance (CMR) and 50 patients showed evidence of viability. Seattle Angina Questionnaire (SAQ) scores were used as a measure of HRQOL.

Results

Pathological Q waves were present in 48 patients (including 19 patients with viable CTO territory) out of 100 patients. Patients with Q waves tended to have worse Seattle Angina Questionnaire (SAQ) scores compared to those with no Q waves (31.2 ± 11.7 vs 45.3 ± 13.9 respectively, p = 0.002), worse LV systolic function and wall motion score index (WMSI) on CMR. They also had significantly less prevalence of viability (p < 0.001). Patients with Q waves and positive viability had lower SAQ scores (37.2 ± 10.1 vs 52.7 ± 13.2 respectively, p = 0.02), higher LVEF and lower WMSI. They also had well developed collateral grade (2.1 ± 1.03 vs 0.7 ± 0.82 respectively, p < 0.001). After successful percutaneous coronary intervention (PCI), in the viable LV group, presence of Q waves was not associated with better LV functional recovery, while those with higher collateral grades were more likely to have better LV functional recovery post CTO-PCI. Patients with Q waves and viable CTO territory showed significantly better SAQ scores compared to pre-PCI (87.3 ± 12.2 vs 37.2 ± 10.1 respectively, p < 0.001). For angina frequency, post–PCI score was 80.2 ± 7.9 compared to 39.2 ± 7.1 before PCI, p < 0.001). Multivariate regression analysis showed that pathological Q waves, Rentrop's collateral grade and the Canadian Cardiovascular Society (CCS) angina class before PCI were the most significant independent predictors of improved HRQOL as reflected by SAQ (OR for Q waves 7.83, 95% CI 1.62–18.91,p 0.003), (OR for Rentrop's collateral grade 8.31,95% CI 2.21–26.33, p < 0.001), (OR for CCS class 8.39, 95% CI 1.21–20.8, p 0.01).

Conclusion

Well-developed collateral circulation could independently predict LV functional recovery after CTO-PCI. Patients with Q waves and viable CTO territory tend to have higher CCS class before revascularization and get significant improvement of HRQOL after PCI. Other predictors of improved HRQOL are Rentrop's collateral grade and worse CCS class before PCI.

Assessing heart disease using a novel magnetocardiography device

The aim of this paper is to present the use of a portable, unshielded magnetocardiograph (MCG) and identify key characteristics of MCG scans that could be used in future studies to identify parameters that are sensitive to cardiac pathology. We recruited 50 patients with confirmed myocardial infarction (MI) within the past 12 weeks and 46 volunteers with no history of cardiac disease. A set of 38 parameters were extracted from MCG features including both signals from the sensor array and from magnetic images obtained from the device and principal component analysis was used to concentrate the information contained in these parameters into uncorrelated predictors. Linear fits of these parameters were then used to examine the ability of MCG to distinguish between sub-groups of patients. In the fist instance, the primary aim of this study was to ensure that MCG has a basic ability to separate a highly polarised patient group (young controls from post infarction patients) and to identify parameters that could be used in future studies to build a formal diagnostic tool kit. Parameters that parameterised left ventricular ejection fraction (LVEF) were identified and an example is presented to show differential low and high ejection fractions.

Validation of electrocardiographic criteria for identifying left ventricular dysfunction in patients with previous myocardial infarction

Background

Eleven criteria correlating electrocardiogram (ECG) findings with reduced left ventricular ejection fraction (LVEF) have been previously published. These have not been compared head‐to‐head in a single study. We studied their value as a screening test to identify patients with reduced LVEF estimated by cardiac magnetic resonance (CMR) imaging.

Methods

ECGs and CMR from 548 patients (age 61 + 11 years, 79% male) with previous myocardial infarction (MI), from the DETERMINE and PRE‐DETERMINE studies, were analyzed. Sensitivity, specificity, positive predictive value (PPV), and negative predictive value (NPV) of each criterion for identifying patients with LVEF ≤ 30% and ≤ 40% were studied. A useful screening test should have high sensitivity and NPV.

Results

Mean LVEF was 40% (SD = 11%); 264 patients (48.2%) had LVEF ≤ 40%, and 96 patients (17.5%) had LVEF ≤ 30%. Six of 11 criteria were associated with a significant lower LVEF, but had poor sensitivity to identify LVEF ≤ 30% (range 2.1%–55.2%) or LVEF ≤ 40% (1.1%–51.1%); NPVs were good for LVEF ≤ 30% (range 82.8%–85.9%) but not for LVEF ≤ 40% (range 52.1%–60.6%). Goldberger's third criterion (RV4/SV4 < 1) and combinations of maximal QRS duration > 124 ms + either Goldberger's third criterion or Goldberger's first criterion (SV1 or SV2 + RV5 or RV6 ≥ 3.5 mV) had high specificity (95.4%–100%) for LVEF ≤ 40%, although seen in only 48 (8.8%) patients; predictive values were similar on subgroup analysis.

Conclusions

None of the ECG criteria qualified as a good screening test. Three criteria had high specificity for LVEF ≤ 40%, although seen in < 9% of patients. Whether other ECG criteria can better identify LV dysfunction remains to be determined.

Both baseline Selvester QRS score and change in QRS score predict prognosis in patients with acute ST-segment elevation myocardial infarction after percutaneous coronary intervention

We aimed to demonstrate the prognostic value of Selvester QRS scores in patients with acute ST-segment elevation myocardial infarction (STEMI).

Early Q-wave morphology in prediction of reperfusion success in patients with ST-segment elevation myocardial infarction treated with primary percutaneous coronary intervention - A cardiac magnetic resonance imaging study

BACKGROUND

Pathological Q-wave (QW) in the electrocardiogram (ECG) before primary percutaneous coronary intervention (primary PCI) is a strong prognostic marker in patients with ST-segment elevation myocardial infarction (STEMI). However, current binary QW criteria are either not clinically applicable or have a lack of diagnostic performance. Accordingly, we evaluated the association between duration, depth and area of QW and markers of the effect of reperfusion (reperfusion success).

METHODS

A total of 516 patients with their first STEMI had obtained an ECG before primary PCI and an acute cardiac magnetic resonance imaging (CMR) at day 1 (interquartile range [IQR], 1-1) and at follow-up at day 92 (IQR, 89-96). The largest measurable QW in ECG was used for analysis of duration, depth and area of QW (QW morphology). The QW morphology was evaluated as a continuous variable in linear regression models and as a variable divided in four equally large groups.

RESULTS

The QW morphology as four equally large groups was significantly associated with all CMR endpoints (p ≤ 0.001) and showed a linear relationship (p ≤ 0.001) with final infarct size (for QW duration, β = 0.47; QW depth, β = 0.41 and QW area, β = 0.39), final infarct transmurality (for QW duration, β = 0.36; QW depth, β = 0.26 and QW area, β = 0.23) and final myocardial salvage index (for QW duration, β = -0.34; QW depth, β = -0.26 and QW area, β = -0.24).

CONCLUSION

Although modest, the QW morphology in STEMI patients showed significant linear association with markers of reperfusion success. Hence, it is suggested that the term pathological is not used as a dichotomous parameter in patients with STEMI but rather evaluated on the basis of extent.

Long-term prognostic value of QRS score in patients with successfully recanalized coronary chronic total occlusion and construction of a predictive nomogram model

BACKGROUND

Few studies have evaluated the prognostic value of QRS score in patients with coronary chronic total occlusion (CTO) after successful recanalization.

METHODS

A total of 474 patients with successfully recanalized coronary CTO were finally included in our study and were followed up for 34.0±5.3months. They were divided into 3 groups: QRS score≥8, QRS score 4-7 and QRS score 0-3. The primary outcome was composite endpoint of major adverse cardiac and cerebral events (MACCEs). A predictive nomogram was established to predict prognosis for MACCEs, and the predictive accuracy of the nomogram was determined by concordance index.

RESULTS

We found that QRS score correlated moderately with wall motion score index (WMSI) (r=0.551, p<0.001), left ventricular ejection fraction (LVEF) (r=-0.339, p<0.001) and coronary collateral circulation (CCC) (r=-0.569, p<0.001). During follow-up, patients with higher QRS score were observed to undergo poor prognosis. After multivariable adjustment, QRS score was still a significant independent predictor for MACCEs [(hazard ratio 1.28, 95% CI 1.18-1.39, p<0.001) in model 1,(hazard ratio 1.30, 95% CI 1.21-1.41, p<0.001) in mode2] and mortality[(hazard ratio 1.33, 95% CI 1.14-1.57, p<0.001) in model 1, (hazard ratio 1.49 , 95% CI 1.24-1.79, p<0.001) in model 2]. Moreover, the nomogram could more accurately predict 3-year MACCEs (c-index: 0.84).

CONCLUSION

QRS score is a strong independent predictor of long-term prognosis in patients with coronary CTO successfully recancalized. The proposed nomograms can be used for the prediction of MACCE in this population.

Dynamic Changes in High-Sensitivity Cardiac Troponin I Are Associated with Dynamic Changes in Sum Absolute QRST Integral on Surface Electrocardiogram in Acute Decompensated Heart Failure

BACKGROUND

A three-dimensional electrocardiographic (ECG) metric, the sum absolute QRST integral (SAI QRST), predicts ventricular arrhythmias in heart failure (HF) patients with implantable cardioverter defibrillator and mechanical response to cardiac resynchronization therapy. We hypothesized that there is an association between patient-specific changes in SAI QRST and myocardial injury as measured by high-sensitivity troponin I (hsTnI).

METHODS

Sum absolute integral QRST on resting 12-lead ECG and hsTnI were measured simultaneously, every 3 hours, and during 12-hour observation period in a prospective cohort of emergency department patients (n = 398; mean age 57.8 ± 13.2 years; 54% female, 64% black), diagnosed with acute coronary syndrome (ACS, n = 28), acutely decompensated HF (acute decompensated heart failure, n = 35), cardiac non-ACS (n = 19), or noncardiac condition (n = 316). Random-effects linear regression analysis assessed the association of SAI QRST and myocardial injury, with adjustment for demographics (age, sex, race), prevalent cardiovascular disease (myocardial infarction, history of revascularization, stroke, and HF), risk factors (diabetes, smoking, hypercholesterolemia, hypertension, and cocaine use), and left bundle branch block.

RESULTS

Within the entire cohort, SAI QRST decreased by 3 (95%CI -5 to -1) mV*ms every 3 hours. A 10-fold increase in hsTnI was associated with a 7.7 (0.6-14.9) mV*ms increase in SAI QRST. In the subgroup of acutely decompensated HF patients (n = 35), a 10-fold increase in hsTnI was associated with a 61.0 (5.9-116.1) mV*ms increase in SAI QRST.

CONCLUSION

Patient-specific time-varying changes in the surface ECG scalar measure of global electrical heterogeneity, as measured by SAI QRST, and in myocardial injury as measured by hsTnI, are independently and directly associated with each other, likely reflecting a common underlying mechanism.

Study of the Blood Supply Fraction of the Ascending Aorta and Its Effect in Diagnosing Early Ascending Aortic Atherosclerosis

OBJECTIVES

To investigate the capacity of blood storage of certain large arteries during diastole, we first studied the ascending aorta by echocardiography. The concept of the blood supply fraction of the ascending aorta was then introduced to evaluate elastic retraction of the ascending aortic wall and determine its role in diagnosing early atherosclerosis of the ascending aorta.

METHODS

First, we enrolled 120 healthy volunteers and divided them into 3 groups according to age: 20 to 35 years (B1 group), 36 to 50 years (B2 group), and 51 to 65 years (B3 group); there were 40 volunteers in each group. We used echocardiography to measure the blood supply fraction in each volunteer and compared the results for each group. Then we enrolled 40 patients (51-65 years) with early atherosclerosis of the ascending aorta, measured the blood supply fraction of each, and compared the results with the B3 group.

RESULTS

The mean blood supply fractions ± SD in the B1, B2, and B3 groups were 21.75% ± 1.53%, 20.76% ± 1.62%, and 18.44% ± 1.19%, respectively. The fraction in the B3 group was significantly lower than those in the B1 and B2 groups (P < .01). The fraction in the patients with early atherosclerosis was 14.92% ± 1.01%, which was obviously lower than that in the B3 group (P < .01).

CONCLUSIONS

The blood supply fraction of the ascending aorta decreases with age, and it could be used as a parameter for diagnosis of early atherosclerosis of the ascending aorta.

Quantitative Assessment of Vectorcardiographic Loop Morphology

Vectorcardiography (VCG), developed 100years ago, characterizes clinically important electrophysiological properties of the heart. In this study, VCG QRS loop roundness, planarity, thickness, rotational angle, and dihedral angle were measured in 81 healthy control subjects (39.0±14.2y; 51.8% male; 94% white), and 8 patients with infarct-cardiomyopathy and sustained monomorphic ventricular tachycardia (VT) (68.0±7.8y, 37.5% male). The angle between two consecutive QRS vectors was defined as the rotational angle, while dihedral angle quantified planar alteration over the QRS loop. In VT subjects, planarity index decreased (0.63±0.22 vs. 0.88±0.10; P=0.014), and dihedral angle was significantly more variable (variance of dihedral angle, median (IQR): 897(575-1450) vs. 542(343-773); P=0.029; rMSSD: 47.7±12.7 vs. 35.1±13.1; P=0.027). Abnormal electrophysiological substrate in VT patients is characterized by the appearance of QRS loop folding, likely due to local conduction block. The presence of fragmented QRS complexes on the 12-lead ECG had low sensitivity (31%) for detecting QRS loop folding on the VCG.

Noninvasive electrocardiographic imaging of chronic myocardial infarct scar

BACKGROUND

Myocardial infarction (MI) scar constitutes a substrate for ventricular tachycardia (VT), and an accurate delineation of infarct scar may help to identify reentrant circuits and thus facilitate catheter ablation. One of the recent advancements in characterization of a VT substrate is its volumetric delineation within the ventricular wall by noninvasive electrocardiographic imaging. This paper compares, in four specific cases, epicardial and volumetric inverse solutions, using magnetic resonance imaging (MRI) with late gadolinium enhancement as a gold standard.

METHODS

For patients with chronic MI, who presented at Glasgow Western Infirmary, delayed-enhancement MRI and 120-lead body surface potential mapping (BSPM) data were acquired and 4 selected cases were later made available to a wider community as part of the 2007 PhysioNet/Computers in Cardiology Challenge. These data were used to perform patient-specific inverse solutions for epicardial electrograms and morphology-based criteria were applied to delineate infarct scar on the epicardial surface. Later, the Rochester group analyzed the same data by means of a novel inverse solution for reconstructing intramural transmembrane potentials, to delineate infarct scar in three dimensions. Comparison of the performance of three specific inverse-solution algorithms is presented here, using scores based on the 17-segment ventricular division scheme recommended by the American Heart Association.

RESULTS

The noninvasive methods delineating infarct scar as three-dimensional (3D) intramural distribution of transmembrane action potentials outperform estimates providing scar delineation on the epicardial surface in all scores used for comparison. In particular, the extent of infarct scar (its percentage mass relative to the total ventricular mass) is rendered more accurately by the 3D estimate. Moreover, the volumetric rendition of scar border provides better clues to potential targets for catheter ablation.

CONCLUSIONS

Electrocardiographic inverse solution providing transmural distribution of ventricular action potentials is a promising tool for noninvasively delineating the extent and location of chronic MI scar. Further validation on a larger data set with detailed gold-standard data is needed to confirm observations reported in this study.

Advanced Electrocardiography Identifies Left Ventricular Systolic Dysfunction in Non-Ischemic Cardiomyopathy and Tracks Serial Change over Time

Electrocardiogram (ECG)-based detection of left ventricular systolic dysfunction (LVSD) has poor specificity and positive predictive value, even when including major ECG abnormalities, such as left bundle branch block (LBBB) within the criteria for diagnosis. Although machine-read ECG algorithms do not provide information on LVSD, advanced ECG (A-ECG), using multiparameter scores, has superior diagnostic utility to strictly conventional ECG for identifying various cardiac pathologies, including LVSD. Methods: We evaluated the diagnostic utility of A-ECG in a case-control study of 40 patients with LVSD (LV ejection fraction < 50% by echocardiography), due to non-ischemic cardiomyopathy (NICM), and 39 other patients without LVSD. Diagnostic sensitivity and specificity for LVSD were determined after applying a previously validated probabilistic A-ECG score for LVSD to stored standard (10 s) clinical 12L ECGs. In 25 of the NICM patients who had serial ECGs and echocardiograms, changes in the A-ECG score versus in echocardiographic LV ejection fraction were also studied to determine the level of agreement between the two tests. Results: Analyses by A-ECG had a sensitivity of 95% for LVSD (93% if excluding N = 11 patients with LBBB) and specificity of 95%. In the 29 NICM patients without LBBB who had serial ECGs, sensitivity improved to 97% when all ECGs were considered. By comparison, human readers in a busy clinical environment had a sensitivity of 90% and specificity of 63%. A-ECG score trajectories demonstrated improvement, deterioration or no change in LVSD, which agreed with echocardiography, in 76% of cases (n = 25). Conclusion: A-ECG scoring detects LVSD due to NICM with high sensitivity and specificity. Serial A-ECG score trajectories also represent a method for inexpensively demonstrating changes in LVSD. A-ECG scoring may be of particular value in areas where echocardiography is unavailable, or as a gatekeeper for echocardiography.

Electrocardiogram for predicting cardiac functional recovery

To investigate if the 12-lead resting electrocardiogram (ECG) is a predictor of left ventricular (LV) functional recovery after revascularization of chronic total coronary artery occlusions (CTO). Revascularization was performed in 58 CTO patients who had impaired regional wall motion. The 12-lead resting ECG was used to evaluate Q-wave, QT dispersion, and other parameters. Pre- and postoperative LV regional wall motions were evaluated by real-time three-dimensional echocardiography (RT-3DE). In patients with non-Q-wave, the wall motion score index (WMSI) was dropped from 1.56 ± 0.31 to 1.12 ± 0.21 (P < 0.05), while there was no significant changes (1.73 ± 0.12 and 1.59 ± 0.23, P > 0.05) for WMSI in patients with Q-wave. Preoperative non-Q-wave at baseline was predicted recovery with 88 % sensitivity and 68 % specificity. Positive predictive value for recovery was 67 % in patients with non-Q-wave. The presence of Q-wave can predict non-recovery of the regional wall motion with 68 % sensitivity and 88 % specificity. For CTO patients treated by revascularization, recovery can be predicted reliably through the analysis of pathological Q-wave on the 12-lead resting ECG.

Automated analysis of the 12-lead ECG in the emergency department: association between high-sensitivity cardiac troponin I and the cardiac electrical biomarker

Timely detection of myocardial injury is essential for appropriate management of patients in emergency department (ED) evaluated for acute myocardial infarction. A novel electrocardiogram (ECG) metric, the Cardiac Electrical Biomarker (CEB), uses eigenvalue modeling of the 12-lead ECG and quantifies dipolar vs. multipolar forces. The goal of this project was to study association between the CEB and high-sensitivity troponin I (HsTnI). We conducted a retrospective study of patients, evaluated in the ED for acute myocardial infarction [n = 411; 57.6 ± 13.2 years; 186 (45%) men; 266 (64%) African-Americans]. Resting 12-lead ECG and HsTnI were measured at presentation and at 3, 6, and 9 hours after the initial measurement. The CEB was measured by the VectraplexECG System (VectraCor, Totowa, NJ). Patient-specific longitudinal analysis was performed to study association between the CEB with HsTnI changes over time. The CEB indicated myocardial injury in 116 (28.2%) study participants. HsTnI was significantly elevated during ED observation period in patients with myocardial injury, diagnosed by the CEB [median (interquartile range), 10.3 (5.2-31.4) vs. 6.3 (3.5-16.5) ng/L; P = 0.002]. In a mixed-effects linear regression adjusted for age, race, and sex, increasing HsTnI was associated with the CEB elevation [β-coefficient, 0.071 (95% confidence interval, 0.008-0.134); P = 0.027]. In conclusion, in patients in ED evaluated for acute myocardial injury, increasing values of HsTnI were associated with increasing values of the CEB, suggesting that myocardial injury is the mechanism that underlines acute changes in the CEB.

A mismatch index based on the difference between measured left ventricular ejection fraction and that estimated by infarct size at three months following reperfused acute myocardial infarction

BACKGROUND AND AIM

The reduction of left ventricular ejection fraction (LVEF) following ST-segment elevation myocardial infarction (STEMI) is a result of infarcted myocardium and may involve dysfunctional but viable myocardium. An index that may quantitatively determine whether LVEF is reduced beyond the expected value when considering only infarct size (IS) has previously been presented based on cardiac magnetic resonance (CMR). The purpose of this study was to introduce the index based on the electrocardiogram (ECG) and compare indices based on ECG and CMR.

METHOD AND RESULTS

In 55 patients ECG and CMR were obtained 3 months after STEMI treated with primary percutaneous coronary intervention. Significant, however moderate inverse relationships were found between measured LVEF and IS. Based on IS and LVEF an IS estimated LVEF was derived and an MI-LVEF mismatch index was calculated as the difference between measured LVEF and IS estimated LVEF. In 41 (74.5%) of the patients there was agreement between the ECG and CMR indices in regards to categorizing indices as >10 or ≤ 10 and generally no significant difference was detected, mean difference of 1.26 percentage points (p = 0.53).

CONCLUSION

The study found an overall good agreement between MI-LVEF mismatch indices based on ECG and CMR. The MI-LVEF mismatch index may serve as a tool to identify patients with potentially reversible dysfunctional but viable myocardium, but future studies including both ECG and CMR are needed.

Relationships between cardiac magnetic resonance imaging abnormalities in the inter-ventricular septum and Selvester QRS scoring criteria for anterior-septal myocardial infarction in patients with right ventricular volume overload

BACKGROUND

Patients with ostium secundum atrial septal defects (ASDs) were studied to determine the prevalence of Selvester anteroseptal myocardial infarction QRS points, and to test the hypothesis that there is a relationship between these criteria and thinning and/or scarring of the inter-ventricular septum (IVS).

METHODS

Demographic, electrocardiographic (ECG), and cardiac magnetic resonance imaging (CMR) data were acquired on 46 patients with a secundum ASD closed percutaneously. Selvester QRS scoring on patient ECGs was performed for areas representing the anteroseptal region of the left ventricle (LV). The IVS to LV free wall thickness ratio was used to assess thinning of the IVS while late gadolinium enhancement (LGE) of the IVS was used for scarring; both using CMR.

RESULTS

Twenty-four (52%) patients scored Selvester QRS points in the anteroseptal region with a mean score of 2.6±1.8. The mean IVS/LV free wall thickness ratio at the basal level and mid-ventricular level was 1.1±0.3 and 1.3±0.3, respectively. There was no association of Selvester QRS points with IVS/LV free wall ratio at the basal (p=0.59) or mid-ventricular (p=0.13) levels. The one patient with LGE in the IVS had 4 Selvester anteroseptal QRS points.

CONCLUSION

The results of our study demonstrate that in our patient population there is a 52% prevalence of Selvester anteroseptal QRS points which are due to thinning and/or scarring of the IVS in only one patient.

Ischemia Index to predict post coronary artery bypass graft change in left ventricular ejection fraction

INTRODUCTION

Both myocardial necrosis and ischemia can decrease the left ventricular ejection fraction (LVEF). An accurate estimate of the relative contributions of these irreversible and potentially reversible factors could lead to better decisions regarding the risk and benefit of coronary artery bypass grafting (CABG). The value of an Ischemia Index calculated by subtracting the ECG estimated infarction dependent LVEF from the measured LVEF to predict post-operative improvement of LVEF was studied in 55 patients with LVEF <40% before CABG. Patients were grouped according to absence or presence of other coexisting ECG confounders.

RESULTS

No significant (p=0.083) relationship was found between the Ischemia Index and the improvement in LVEF after CABG in the overall population, but a strong trend was present in the patients with ECGs without confounding QRS changes (p=0.056).

CONCLUSION

These results suggest a positive relationship between the Ischemia Index and improvement of LVEF after CABG in patients without electrocardiographic confounders, but a prospective study using a larger sample is needed.

The Correlation between Infarct Size and the QRS Axis Change after Thrombolytic Therapy in ST Elevation Acute Myocardial Infarction

OBJECTIVE

Electrocardiography (ECG) may be a practical guiding tool for prognostic infarct sizing in ST elevation acute myocardial infarction (STEAMI). In this study, we sought to find a relation between the infarct size and the change in the QRS axis after thrombolytic therapy.

MATERIALS AND METHODS

Patients with STEAMI who received thrombolytic therapy were selected retrospectively. The mean QRS axes of two ECGs (before and 90 minutes after thrombolytic therapy) were calculated. Creatinine kinase MB (CKMB) was used as the marker of infarct size.

RESULTS

We did not detect any correlation between infarct size and change in the QRS axis with respect to any myocardial infarction MI localizations (p=0.80). However, in the isolated inferior MI group, there was a good correlation between CKMB and change in the QRS axis (r=-0.52 p=0.049).

CONCLUSION

The change in the QRS axis is rarely emphasized, providing a practical and promising tool for evaluating both the efficiency of the thrombolytic therapy and prognostic infarct sizing.

A new electrocardiogram marker to identify patients at low risk for ventricular tachyarrhythmias: sum magnitude of the absolute QRST integral

OBJECTIVE

We proposed and tested a novel electrocardiogram marker of risk of ventricular arrhythmias (VAs).

METHODS

Digital orthogonal electrocardiograms were recorded at rest before implantable cardioverter-defibrillator (ICD) implantation in 508 participants of a primary prevention ICDs prospective cohort study (mean ± SD age, 60 ± 12 years; 377 male [74%]). The sum magnitude of the absolute QRST integral in 3 orthogonal leads (SAI QRST) was calculated. A derivation cohort of 128 patients was used to define a cutoff; a validation cohort (n = 380) was used to test a predictive value.

RESULTS

During a mean follow-up of 18 months, 58 patients received appropriate ICD therapies. The SAI QRST was lower in patients with VA (105.2 ± 60.1 vs 138.4 ± 85.7 mV ms, P = .002). In the Cox proportional hazards analysis, patients with SAI QRST not exceeding 145 mV ms had about 4-fold higher risk of VA (hazard ratio, 3.6; 95% confidence interval, 1.96-6.71; P < .0001) and a 6-fold higher risk of monomorphic ventricular tachycardia (hazard ratio, 6.58; 95% confidence interval, 1.46-29.69; P = .014), whereas prediction of polymorphic ventricular tachycardia or ventricular fibrillation did not reach statistical significance.

CONCLUSION

High SAI QRST is associated with low risk of sustained VA in patients with structural heart disease.

An ECG index of myocardial scar enhances prediction of defibrillator shocks: an analysis of the Sudden Cardiac Death in Heart Failure Trial

BACKGROUND

Only a minority of patients receiving implantable cardioverter-defibrillators (ICDs) for the primary prevention of sudden death receive appropriate shocks, yet almost as many are subjected to inappropriate shocks and device complications. Identifying and quantifying myocardial scar, which forms the substrate for ventricular tachyarrhythmias, may improve risk stratification.

OBJECTIVE

This study sought to determine whether the absence of myocardial scar detected by novel 12-lead electrocardiographic (ECG) Selvester QRS scoring criteria identifies patients with low risk for appropriate ICD shocks.

METHODS

We applied QRS scoring to 797 patients from the ICD arm of the Sudden Cardiac Death in Heart Failure Trial. Patients were followed up for a median of 45.5 months for ventricular tachycardia/fibrillation treated by the ICD or sudden tachyarrhythmic death (combined group referred to as VT/VF).

RESULTS

Increasing QRS score scar size predicted higher rates of VT/VF. Patients with no scar (QRS score = 0) represented a particularly low-risk cohort with 48% fewer VT/VF events than the rest of the population (absolute difference 11%; hazard ratio 0.52, 95% confidence interval 0.31 to 0.88). QRS score scar absence versus presence remained a significant prognostic factor after controlling for 10 clinically relevant variables. Combining QRS score (scar absence versus presence) with ejection fraction (≥ 25% versus < 25%) distinguished low-, middle-, and high-risk subgroups with 73% fewer VT/VF events in the low-risk versus high-risk group (absolute difference 22%; hazard ratio = 0.27, 95% confidence interval 0.12 to 0.62).

CONCLUSION

Patients with no scar by QRS scoring have significantly fewer VT/VF events. This inexpensive 12-lead ECG tool provides unique, incremental prognostic information and should be considered in risk-stratifying algorithms for selecting patients for ICDs.

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.

Electrocardiographic predictors of atrial fibrillation

BACKGROUND

Atrial fibrillation (AF) is the most prevalent arrhythmia in the United States and accounts for more than 750,000 strokes per year. Noninvasive predictors of AF may help identify patients at risk of developing AF. Our objective was to identify the electrocardiographic characteristics associated with onset of AF.

METHODS

This was a retrospective cohort analysis of 42,751 patients with electrocardiograms (ECGs) ordered by physician's discretion and analyzed using a computerized system. The population was followed for detection of AF on subsequent ECGs. Cox proportional hazard regression analysis was performed to test the association between these ECG characteristics and development of AF.

RESULTS

For a mean follow-up of 5.3 years, 1,050 (2.4%) patients were found to have AF on subsequent ECG recordings. Several ECG characteristics, such as P-wave dispersion (the difference between the widest and narrowest P waves), premature atrial contractions, and an abnormal P axis, were predictive of AF with hazard ratio of approximately 2 after correcting for age and sex. P-wave index, the SD of P-wave duration across all leads, was one of the strongest predictors of AF with a concordance index of 0.62 and a hazard ratio of 2.7 (95% CI 2.1-3.3) for a P-wave index >35. These were among the several independently predictive markers identified on multivariate analysis.

CONCLUSIONS

Several ECG markers are independently predictive of future onset of AF. The P index, a measurement of disorganized atrial depolarization, is one of the strongest predictors of AF. The ECG contains valuable prognostic information that can identify patients at risk of AF.

Added value of a resting ECG neural network that predicts cardiovascular mortality

BACKGROUND

The resting 12-lead electrocardiogram (ECG) remains the most commonly used test in evaluating patients with suspected cardiovascular disease. Prognostic values of individual findings on the ECG have been reported but may be of limited use.

METHODS

The characteristics of 45,855 ECGs ordered by physician's discretion were first recorded and analyzed using a computerized system. Ninety percent of these ECGs were used to train an artifical neural network (ANN) to predict cardiovascular mortality (CVM) based on 132 ECG and four demographic characteristics. The ANN generated a Resting ECG Neural Network (RENN) score that was then tested in the remaining ECGs. The RENN score was finally assessed in a cohort of 2189 patients who underwent exercise treadmill testing and were followed for CVM.

RESULTS

The RENN score was able to better predict CVM compared to individual ECG markers or a traditional Cox regression model in the testing cohort. Over a mean of 8.6 years, there were 156 cardiovascular deaths in the treadmill cohort. Among the patients who were classified as intermediate risk by Duke Treadmill Scoring (DTS), the third tertile of the RENN score demonstrated an adjusted Cox hazard ratio of 5.4 (95% CI 2.0-15.2) compared to the first RENN tertile. The 10-year CVM was 2.8%, 8.6% and 22% in the first, second and third RENN tertiles, respectively.

CONCLUSIONS

An ANN that uses the resting ECG and demographic variables to predict CVM was created. The RENN score can further risk stratify patients deemed at moderate risk on exercise treadmill testing.

ECG quantification of myocardial scar in cardiomyopathy patients with or without conduction defects: correlation with cardiac magnetic resonance and arrhythmogenesis

BACKGROUND

Myocardial scarring from infarction or nonischemic fibrosis forms an arrhythmogenic substrate. The Selvester QRS score has been extensively validated for estimating myocardial infarction scar size in the absence of ECG confounders, but has not been tested to quantify scar in patients with hypertrophy, bundle branch/fascicular blocks, or nonischemic cardiomyopathy. We assessed the hypotheses that (1) QRS scores (modified for each ECG confounder) correctly identify and quantify scar in ischemic and nonischemic patients when compared with the reference standard of cardiac magnetic resonance using late-gadolinium enhancement, and (2) QRS-estimated scar size predicts inducible sustained monomorphic ventricular tachycardia during electrophysiological testing.

METHODS AND RESULTS

One hundred sixty-two patients with left ventricular ejection fraction < or =35% (95 ischemic, 67 nonischemic) received 12-lead ECG and cardiac magnetic resonance using late-gadolinium enhancement before implantable cardioverter defibrillator placement for primary prevention of sudden cardiac death. QRS scores correctly diagnosed cardiovascular magnetic resonance scar presence with receiver operating characteristics area under the curve of 0.91 and correlation for scar quantification of r=0.74 (P<0.0001) for all patients. Performance within hypertrophy, conduction defect, and nonischemic subgroups ranged from area under the curve of 0.81 to 0.94 and r=0.60 to 0.80 (P<0.001 for all). Among the 137 patients undergoing electrophysiological or device testing, each 3-point QRS-score increase (9% left ventricular scarring) was associated with an odds ratio for inducing monomorphic ventricular tachycardia of 2.2 (95% CI, 1.5 to 3.2; P<0.001) for all patients, 1.7 (1.0 to 2.7, P=0.04) for ischemics, and 2.2 (1.0 to 5.0, P=0.05) for nonischemics.

CONCLUSIONS

QRS scores identify and quantify scar in ischemic and nonischemic cardiomyopathy patients despite ECG confounders. Higher QRS-estimated scar size is associated with increased arrhythmogenesis and warrants further study as a risk-stratifying tool.

The relationship between left ventricular ejection fraction and infarct size assessed by MRI

OBJECTIVES

We sought to study the relationship between left ventricular ejection fraction (LVEF) and infarct size in patients with ischemic heart disease (IHD) using magnetic resonance imaging (MRI), and to determine a dysfunction index based on the maximum possible LVEF in relation to infarct size.

DESIGN

In 149 patients with chronic IHD, LVEF and infarct size were quantified by MRI. Dysfunction index was defined as the maximum possible LVEF minus measured LVEF.

RESULTS

The maximum possible LVEF was found to be LVEF=72.2-[1.18*infarct size]. Dysfunction index for the study population was mean 20 (range -6 to 57), 74% of the study population had a dysfunction index >10 and 44% had a dysfunction index >20.

CONCLUSIONS

The present study suggests that infarct size by MRI can be used to estimate a maximum possible LVEF and a dysfunction index. The distribution of dysfunction index in the population suggests a considerable prevalence of dysfunctional but viable myocardium. Future studies are needed to assess if the dysfunction index can be useful to assess the potential for improvement in LVEF following revascularization.

Predischarge QRS score and risk for heart failure after first ST-elevation myocardial infarction

BACKGROUND

The prognostic value of the QRS score, a simple index of infarct size after a first ST-elevation myocardial infarction, has not been adequately explored in the reperfusion era.

METHODS AND RESULTS

We prospectively followed up 100 consecutive survivors of a first ST-elevation myocardial infarction (aged 64 +/- 13 years, 77% were male) without bundle branch block or paced rhythm at hospital discharge for 3 months. The modified 32-point QRS score was calculated as part of the predischarge evaluation. The predefined primary endpoint was the composite of death or hospitalization for heart failure. By 3 months, 6 patients died and 16 patients were readmitted for heart failure, resulting in a 22% primary endpoint rate. Patients with a QRS score >/= 3 at hospital discharge (n = 38) had significantly more events compared with those with a QRS score < 3 (44.7% vs. 8.2%, P < .001), and all six deaths occurred among patients with a QRS score >/= 3 (P = .002). A QRS score < 3 reliably predicted heart-failure free survival during the follow-up period (negative predictive value 91.9%). In multivariate models, the QRS score was an independent predictor of the primary endpoint (hazard ratio = 1.4 per point, 95% confidence interval 1.1-1.8, P = .003).

CONCLUSION

For patients surviving a first ST-elevation myocardial infarction, the predischarge QRS score provides powerful prognostic information on short-term outcomes, including mortality and readmission for heart failure.

Single-lead electrocardiographic variables in the detection of prior myocardial infarction with respect to Q-wave status and infarct age

OBJECTIVES

Conventionally, the detection of prior myocardial infarction (MI) is based on QRS abnormalities, which may ignore non-Q-wave MI (NQMI). We aimed at finding automatically applicable quantitative ECG variables for diagnosing prior MI.

METHODS

Body surface potential mapping (BSPM) was registered and automatically analyzed in 144 patients with prior MI and in 75 healthy controls. The MI was defined according to its age as recent or old, and Q-wave status as Q-wave MI (QMI) or NQMI.

RESULTS

The QRSSTT integral, the STT integral and the T-wave apex amplitude applied in single, selected leads were found to be the optimal parameters in the detection of prior MI. The areas under the receiver-operating characteristic curves (AUC) were 89% for each, and detection was equal in old and recent MI (AUCs from 87 to 90%), and in QMI and NQMI (AUCs from 88 to 90%).

CONCLUSIONS

The quantitative, automatically applicable single-lead variables comprising ventricular repolarization was effective in detecting prior MI, irrespective of the time elapsed from MI or the Q-wave status. These variables could be suitable for population studies and health screening purposes and are applicable to automatic ECG diagnostics of prior MI.

Prognostic value of the computerized ECG in Hispanics

BACKGROUND

The prevalence and prognostic values of electrocardiogram (ECG) abnormalities in Hispanics have not been compared to other ethnicities in a large population. Despite a worse cardiovascular risk profile, the prevalence of cardiovascular disease is lower in Hispanics compared to non-Hispanics.

HYPOTHESIS

We hypothesized that ECG abnormalities were less common in Hispanics and were not as strongly associated with cardiovascular mortality.

METHODS

45,563 ECGs ordered for usual clinical indications in a Veteran's hospital were available for analysis. 1,392 patients who died within one week of the ECG were excluded. Demographic characteristics were recorded and the population was followed for an average of 7.5 years using the California Death Index. The presence of baseline ECG characteristics were recorded and analyzed using the GE/Marquette computerized ECG system. Age, sex and heart rate adjusted Cox hazard ratio analyses were performed.

RESULTS

Being Hispanic was associated with lower cardiovascular death, with a hazard ratio (HR) of 0.76 (95% CI 0.65-0.89). Findings such as atrial fibrillation, presence of Q-waves, left ventricular hypertrophy (LVH), upright T-waves in aortic valve replacement (aVR) and cardiac Infarction Injury Scores > 6 were significantly less prevalent in Hispanics than in non-Hispanics. These findings were similarly associated with increased cardiovascular mortality in both groups, each with a HR of approximately 2.

CONCLUSION

The lower prevalence of ECG characteristics associated with coronary heart disease, atrial fibrillation and left ventricular hypertrophy support prior observations that cardiovascular disease is less prevalent in the Hispanic population. These findings, however, are similarly associated with increased mortality compared to non-Hispanics.

Comparison of effectiveness of enoxaparin versus unfractionated heparin to reduce silent and clinically apparent acute myocardial infarction in patients presenting with non-ST-segment elevation acute coronary syndrome

Electrocardiographic (ECG) estimates of myocardial infarct size based on the Selvester ECG score have been shown to predict mortality and left ventricular function after acute myocardial infarction (AMI). This score has also been used to identify not clinically apparent AMI ("silent" AMI) and to determine treatment effect, suggesting it could serve as a clinical trial end point. The objective of this study was to compare the rate of silent AMI as measured by the Selvester QRS score in patients with a non-ST-segment elevation acute coronary syndrome treated with enoxaparin versus intravenous unfractionated heparin who were participating in a continuous ECG monitoring substudy of the Efficacy and Safety of Subcutaneous Enoxaparin in Non-Q-wave Coronary Events study (ESSENCE) and INTegrelin and Enoxaparin Randomized Assessment of acute Coronary syndrome Treatment trial (INTERACT). Enoxaparin was associated with a 56% relative risk decrease in silent AMI at 96 hours compared with unfractionated heparin (2.7% vs 6.1% p = 0.03). Similarly, enoxaparin decreased Holter-detected myocardial ischemia compared with unfractionated heparin (18.7% vs 35.9%, p = 0.03). In conclusion, enoxaparin significantly decreased the composite of silent AMI or clinical AMI and death at 1 year (9.3% vs 21%, p = 0.0001).

Acute anterior myocardial infarction followed by acute inferoposterior myocardial infarction: the case of the necrotic QRS counterpoise

A case of a 55-year-old man who suffered an acute anterior myocardial infarction (MI) followed by an acute inferoposterior MI 1 month later, which led to his demise from cardiogenic shock, is presented. The electrocardiogram after his second MI resulted in profound decrease in the amplitude of the QRS complexes and cancellation of the features of the previous anterior MI (necrotic QRS counterpoise). The implications of these electrocardiogram alterations, particularly when using this modality in QRS scoring systems for estimation of infarct size or left ventricular function, are discussed.

Correlation between ECG and myocardial perfusion after mechanical reperfusion of acute myocardial infarction

The identification of viable myocardium after myocardial infarction (MI) carries major prognostic impact. Due to myocardial stunning early after successful mechanical reperfusion of acute myocardial infarction, analysis of myocardial perfusion but not of contractile function can be used to differentiate between necrotic and viable myocardium. Although being widely regarded as an indicator of infarct transmurality, the relation between post-infarct Q-wave formation and the amount of viable myocardium has not been studied. We hypothesized that there was a correlation between the extent of Q-wave formation and the extent of perfusion abnormalities on myocardial contrast echocardiography early after successful mechanical reperfusion of first acute myocardial infarction and that the extent of post-infarct Q-wave formation might therefore be used as a simple estimate of the amount of viable myocardium.

METHODS AND RESULTS

47 patients with first MI and treated by direct PCI were enrolled. Patients were divided into 3 groups according the presence and number of abnormal Q waves (group A-no abnormal Q wave; group B-< or =2 abnormal Q waves, group C-> or =3 abnormal Q waves). Left ventricular pump function was defined by ejection fraction (EF) on ventriculography and wall motion score index (WMSI) on echocardiography. Myocardial perfusion was defined by perfusion score index (PSI) on myocardial contrast echocardiography. Patients in group A had significantly better LV function than patients in other groups [EF 57+/-5 vs. 48+/-11% (group B) and 47+/-10% (group C); p<0.05], also WMSI was the best in this group [1.34+/-0.22 vs. 1.67+/-0.39 (group B) and 1.68+/-0.31 (group C); p<0.01]. Myocardial perfusion assessed by PSI was best in group A (1.2+/-0.3, p<0.05). With respect to PSI, there was a significant difference between group B and C (1.41+/-0.21 vs. 1.56+/-0.29; p<0.05), even though EF and WMSI did not differ in these groups. The amount of perfused segments with severe wall motion abnormality was higher in group B compared to group C (47% vs. 25%; p<0.05).

CONCLUSION

In patients after successful mechanical reperfusion of first MI, the extent of Q-wave formation on ECG may be regarded as a corollary of the amount of myocardial microvascular damage and may, therefore, be used to estimate the amount of viable myocardium post-infarct.

Resting 12-lead electrocardiogram as a reliable predictor of functional recovery after recanalization of chronic total coronary occlusions

BACKGROUND

A major goal of revascularization is the recovery of left ventricular (LV) function. Nuclear imaging techniques are widely used for detecting recovery of function with a good sensitivity, but only moderate specificity. Predictors of recovery in chronic total coronary occlusions (CTO) are not investigated.

HYPOTHESIS

The 12-lead-resting electrocardiogram (ECG) is a predictor of LV recovery after successful recanalization of CTO.

METHODS

Successful recanalization of CTO was performed in 127 patients. Of these, 62 patients, who constitute the study group, had impaired regional wall motion prior to recanalization. The 12-lead resting ECG was evaluated for Q-wave areas and parameters of QT dispersion. Impairment of regional wall motion was evaluated by LV angiogram at baseline and at follow-up.

RESULTS

Angiographic follow-up after 5 +/- 1.4 months documented reocclusion in eight patients. Complete follow-up with a patent coronary artery and an ECG without bundle-branch block was available in 43 patients. Wall motion severity index (WMSI) improved from -2.92 +/- 0.28 to -1.34 +/- 0.61 (p < 0.001) in patients without Q waves, whereas it was unchanged in patients with Q waves (-3.01 +/- 0.30 and -2.81 +/- 0.32). Absence of Q waves at baseline predicted recovery of regional wall motion with 89% sensitivity and 67% specificity. Positive predictive value for recovery was 68% in patients without Q waves, but only 11% in patients with Q waves. In multivariate analysis, only absence of Q waves predicted improvement in WMSI (p = 0.01).

CONCLUSIONS

In patients with recanalization of CTO, recovery of regional wall motion is reliably predicted by analysis of the resting 12-lead ECG for pathologic Q waves.

Ischemic Preconditioning by Unstable Angina Reduces the Release of CK-MB Following CABG and Stimulates Left Ventricular HSP-72 Protein Expression

BACKGROUND AND AIM

Whether the CK-MB reducing effect of ischemic preconditioning (IP) by unstable angina within 24 to 48 hours before CABG is achieved by early or by delayed preconditioning of left ventricular myocardium in humans is unknown. We investigated whether IP is associated with phosphorylation of p38 MAPK (characteristic for early preconditioning) or with increased protein expression of HSP-72 (characteristic for delayed preconditioning) at the time of CABG in patients.

METHODS

Nineteen patients were grouped according to the occurrence of ischemic episodes within 48 hours before CABG. The patients without angina were assigned to the control group (CON, n = 10) whereas patients who had experienced angina within 48 hours before CABG were assigned to the preconditioned group (IP, n = 9). The effect of IP on the CABG induced maximal release of creatine kinase (CK) and CK-MB was examined. Left ventricular biopsy specimens taken immediately before cross clamping from ischemic (ISCH) and from reference (REF) areas were processed to analyze p38 MAPK phosphorylation and HSP-72-protein expression.

RESULTS

While IP significantly reduced CK-MB (18.7 +/- 1.3 vs. 13.8 +/- 1.5 U/L, mean +/- SEM, p < 0.05), it only tended to reduce CK (292.7 +/- 32.8 vs. 274.1+/-31.1 U/L, p = NS, mean +/- SEM). CK-MB release for any given cross-clamp time was significantly reduced by IP (regression lines: CON, y= 0.4x+ 2, r= 0.8; IP, y= 0.1x+ 10, r= 0.2; p < 0.01, ANCOVA). There was no effect of IP on left ventricular p38 MAPK phosphorylation. IP increased left ventricular HSP-72-protein expression in ischemic areas when compared to reference areas (1.78 +/- 0.35 vs. 2.58 +/- 0.65, REF vs. ISCH, PhosphorImager units x10(6), mean +/- SEM, p < 0.05, ANCOVA).

CONCLUSIONS

Thus, in the human left ventricular myocardium there is a second window of protection lasting for at least 48 hours, while at that time the early phase of preconditioning has already gone.

Electrocardiographic damage scores and cardiovascular mortality

BACKGROUND

A number of electrocardiogram (ECG) classification systems have been developed to estimate cardiac injury, infarct size, and left ventricular function. Although many studies have documented an association between clinical, imaging, and autopsy data, few have evaluated their prognostic value.

METHODS AND RESULTS

ECGs from 46,933 patients were analyzed using computerized measurements and algorithms. The Simplified Selvester Score, the Cardiac Infarction Injury Score (CIIS), and a Q-wave score were calculated. Other ECG characteristics such as left ventricular hypertrophy and bundle-branch blocks were also evaluated. The main outcome was cardiovascular (CV) mortality. During a mean follow-up of 6 years, the CIIS outperformed all other ECG classifications in determining prognosis. Going from lowest to highest tertile of CIIS, each step had a hazard ratio of 1.39 (CI 1.32-1.45) or a 39% increase in risk per tertile. Using clinically based thresholds, the annual mortality for high-risk CIIS was 4.5% (CI 4.0-4.6) versus 0.3% (CI 0.0-1.3) for those in the low-risk group.

CONCLUSIONS

A low-risk damage score was associated with a <1% annual CV mortality and a high-risk damage score with annual CV mortality of >4%. A damage score should be calculated as part of all computerized ECG interpretations.

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.

Quantitative clinical assessment of chronic anterior myocardial infarction with delayed enhancement magnetic resonance imaging and QRS scoring

BACKGROUND

Both the regional and global myocardial extent of chronic myocardial infarction (MI) are important prognostic factors for length and quality of life and also crucial for the choice of therapy in patients with ischemic heart disease. Our aim was to develop and validate techniques for comparison between regional and global size of remote anterior MI in the left ventricle quantified with both magnetic resonance imaging (MRI) and electrocardiogram (ECG).

METHODS

Delayed-enhancement (DE) MRI was used as a clinical "gold standard" for MI size to evaluate the extent of MI estimated with the commonly available standard 12-lead ECG. A method for comparing global and regional quantifications of MI with DE-MRI and ECG was developed. The Selvester QRS-scoring system was used for estimating MI size electrocardiographically.

RESULTS

Twenty-five patients with chronic single anterior MI, documented with DE-MRI, were studied. The best agreement for mean % MI per regional segment of the left ventricle was found in the middle third (26% vs 27%), whereas the most significant discrepancy was found in the apex (56% vs 30%). The global MI size of the left ventricle averaged 21 +/- 9% with DE-MRI and 22% +/- 12% with ECG, with a correlation of r = 0.40 (P <.05).

CONCLUSIONS

The current Selvester QRS scoring system performs well for quantifying anterior MI in the mid-regions of the left ventricle. The diagnostic performance of the Selvester QRS-scoring system for quantifying MI in the other regions, particularly the left ventricular apex, can potentially be improved, with DE-MRI as the gold standard.

Value of the electrocardiogram in predicting left ventricular enlargement and dysfunction after myocardial infarction

To identify electrocardiographic predictors of left ventricular enlargement or persistent dysfunction following a myocardial infarction. Baseline and predischarge 12-lead electrocardiograms (ECGs) from 272 patients with anterior myocardial infarction who were enrolled in the Healing and Early Afterload Reducing Therapy trial were evaluated and related to echocardiographic data obtained at baseline and day 90. ST-segment elevation, QRS score, and number of negative T waves were assessed at both time points. The majority of patients (87%; n = 237) received reperfusion therapy. Multivariate models were used to adjust for potential confounders, including maximal creatine kinase level and ejection fraction at baseline. None of the baseline electrocardiographic variables independently predicted ventricular enlargement or recovery of function. In contrast, the sum of ST- and maximum ST-segment elevation, and the number of leads with ST-segment elevation > or =1 mm in the predischarge ECG, were independent predictors of ventricular enlargement from baseline to day 90. Each lead with ST-segment elevation > or =1 mm was associated with 3.5 mL of ventricular enlargement (95% confidence interval [CI]: 1.6 to 5.5 mL; P <0.0001). Similarly, the sum of ST-segment elevation (odds ratio [OR] = 0.78; 95% CI: 0.69 to 0.89; P <0.0001), the maximum ST-segment elevation (OR = 0.25; 95% CI: 0.13 to 0.45; P <0.0001), and the number of leads with ST-segment elevation > or =1 mm (OR = 0.58; 95% CI: 0.45 to 0.74; P <0.0001) were independently associated with a lower likelihood of recovery of function at day 90. Predischarge ECG may be a useful tool for early identification of patients at risk of ventricular enlargement and persistent dysfunction following myocardial infarction.

Is anteroseptal myocardial infarction an appropriate term?

Anteroseptal myocardial infarction is defined by the presence of electrocardiographic Q-waves limited to precordial leads V(1) to V(2), V(3), or V(4). We sought to determine whether this term is appropriate by correlating electrocardiographic, echocardiographic, and angiographic findings. We studied 50 consecutive patients admitted for a first acute myocardial infarction with Q-waves in precordial leads V(1) to V(2)-V(4), and who had undergone echocardiography and coronary angiography during hospitalization. Echocardiograms in the apical long-axis, two-chamber, and four-chamber views were studied using a wall motion scoring index.Q-waves were present in precordial leads V(1)-V(2) in 4 patients, V(1)-V(3) in 28 patients, and V(1)-V(4) in the remaining 18 patients. The presumptive culprit lesion was in the proximal segment of the left anterior descending artery in 15 patients, in the middle segment in 33 patients, and indeterminate in 2 patients. This lesion was before the first septal branch in 19 patients and after the first septal branch in 29. Mean (+/- SD) left ventricular ejection fraction was 51% +/- 10%. Echocardiographic analysis showed that the septal wall was never the only wall that was affected. However, the apex was affected in all patients and was the only wall that was affected in 26 (52%) patients (apical wall index, 2.1 +/- 0.5). In the remaining 24 patients, the septum was also affected (septal index, 1.5 +/- 0.3), but less severely than was the apex (apical index, 2.3 +/- 0.4; P <0.0001 vs. septum). In these 24 patients, the anterior and lateral walls were also affected (anterior index, 1.4 +/- 0.4; lateral index, 1.1 +/- 0.2), but again, less severely than was the apex (P <0.0001 for both vs. apex). Neither angiographic nor echocardiographic data support the notion of an isolated anteroseptal myocardial infarction. Left anterior descending artery involvement appears more often to be midsegment and postseptal. The apex is always and principally affected. These findings suggest that anteroseptal myocardial infarction is a misnomer and that the V(1) to V(2)-V(4) Q-wave pattern should be considered to indicate a predominantly apical, and generally limited, myocardial infarction.