Grade 3 ischemia on the admission electrocardiogram is associated with severe microvascular injury on cardiac magnetic resonance imaging after ST elevation myocardial infarction

High-risk ECG patterns in ST elevation myocardial infarction for mortality prediction

AIM

We explored the pre-intervention (first medical contact) electrocardiographic (ECG) patterns and their relation to survival among patients with acute myocardial infarction, who presented either with ST elevation (ST elevation myocardial infarction, STEMI) or LBBB, and who underwent emergent coronary angiography in a region with a 24/7/365 STEMI network.

METHODS

This is a retrospective analysis of 1363 consecutive patients hospitalized for first STEMI between the years 2014 and 2018. We assessed the prognostic significance of a variety of ECG categories, including location of ST elevation, severity of ischemia, intraventricular and atrioventricular conduction disorders, atrial fibrillation or flutter, junctional rhythms, heart rate, left ventricular hypertrophy and Q waves. The primary outcome was all-cause mortality between January 2014 and the end of 2020.

RESULTS

The mean age of the patients was 67.9 (SD 12.8) years. The majority were treated by percutaneous coronary intervention (93.8%, n = 1278). Median follow-up time was 3.7 years (IQR 2.5-5.1 years) during which 22.5% (n = 307) of the patients died. According to Cox regression analysis, adjusted for pre-existing conditions and age, the ECG variables with statistically significant association with survival were elevated heart rate (>100 bpm) (HR 2.34, 95% CI 1.75-3.12), atrial fibrillation or flutter (HR 1.94, 95% CI 1.41-2.67), left bundle branch block (LBBB) (HR 2.62, 95% CI 1.49-4.63) and non-specific intraventricular conduction delay (NIVCD) (HR 1.85, 95% CI 1.22-2.89).

CONCLUSION

Higher heart rate, atrial fibrillation or flutter, LBBB and NIVCD are associated with worse outcome in all-comers with STEMI. Ischemia severity was not associated with impaired prognosis.

The prognostic significance of grade of ischemia in the ECG in patients with ST-elevation myocardial infarction: A substudy of the randomized trial of primary PCI with or without routine manual thrombectomy (TOTAL trial)

BACKGROUND

The importance of the grade of ischemia (GI) ECG classification in the risk assessment of patients with STEMI has been shown previously. Grade 3 ischemia (G3I) is defined as ST-elevation with distortion of the terminal portion of the QRS complex in two or more adjacent leads, while Grade 2 ischemia (G2I) is defined as ST-elevation without QRS distortion. Our aim was to evaluate the prognostic impact of the GI classification on the outcome in patients with STEMI.

METHODS

7,211 patients from the TOTAL trial were included in our study. The primary outcome was a composite of cardiovascular death, recurrent myocardial infarction (MI), cardiogenic shock, or New York Heart Association (NYHA) class IV heart failure within one year.

RESULTS

The primary outcome occurred in 153 of 1,563 patients (9.8%) in the G3I group vs. 364 of 5,648 patients (6.4%) in the G2I group (adjusted HR 1.27; 95% CI, 1.04 - 1.55; p=0.022). The rate of cardiovascular death (4.8% vs. 2.5%; adjusted HR 1.48; 95% CI 1.09 - 2.00; p=0.013) was also higher in patients with G3I.

CONCLUSIONS

G3I in the presenting ECG was associated with an increased rate of the composite of cardiovascular death, recurrent MI, cardiogenic shock, or NYHA class IV heart failure within one year compared to patients with G2I. Patients with G3I also had a higher cardiovascular death compared to patients with G2I.

Electrocardiogram to predict reperfusion success in late presenters with ST-segment elevation myocardial infarction treated with primary percutaneous coronary intervention

BACKGROUND

Clinical decision-making in patients with ST-segment elevation myocardial infarction (STEMI) presenting beyond 12 h of symptom onset (late presenters) is challenging. However, the electrocardiogram (ECG) may provide helpful information. We investigated the association between three ECG-scores and myocardial salvage and infarct size in late presenters treated with primary percutaneous coronary intervention (primary PCI).

METHODS

Sixty-six patients with STEMI and ongoing symptoms presenting 12-72 h after symptom onset were included. Cardiac magnetic resonance was performed at day 1 (interquartile range [IQR], 1-1) and at follow-up at day 93 (IQR, 90-98). The pre-PCI ECG was analyzed for the presence of pathological QW (early QW) as well as Anderson-Wilkins acuteness score (AW-score), the classic Sclarovsky-Birnbaum Ischemia Grading System (classic SB-IG-score) and a modified SB-IG-score including any T-wave morphologies.

RESULTS

Early QW was associated with a larger myocardium at risk (39 ± 12 versus 33 ± 12; p = 0.030) and final infarct size (20 ± 11 versus 14 ± 9; p = 0.021) as well as a numerical lower final myocardial salvage (0.52 ± 0.19 versus 0.61 ± 0.23; p = 0.09). The association with final infarct size disappeared after adjusting for myocardium at risk. An AW-score < 3 showed a trend towards a larger final infarct size (18 ± 11 versus 11 ± 11; p = 0.08) and was not associated with salvage index (0.55 ± 0.20 versus 0.65 ± 0.30; p = 0.23). The classic and modified SB-IG-score were not associated with final infarct size (modified SB-IG-score, 17 ± 10 versus 21 ± 13; p = 0.28) or final myocardial salvage (0.53 ± 0.20 versus 0.53 ± 0.26; p = 0.96).

CONCLUSION

Of three well-established ECG-scores only early QW and AW-score < 3 showed association with myocardium at risk and infarct size to some extent, but the association with myocardial salvage was weak. Hence, neither of the three investigated ECG-scores are sufficient to guide clinical decision-making in patients with STEMI and ongoing symptoms presenting beyond 12 h of symptom onset.

Automatic electrocardiographic algorithm for assessing severity of ischemia in ST-segment elevation myocardial infarction

BACKGROUND

Terminal QRS distortion on the electrocardiogram (ECG) is a sign of severe ischemia in patients with STEMI and can be quantified by the Sclarovsky-Birnbaum Severity of Ischemia. Due to score complexity, it has not been applied in clinical practice. Automatic scoring of digitally recorded ECGs could facilitate clinical application. We aimed to develop an automatic algorithm for the severity of ischemia.

METHODS

Development set: 50 STEMI ECGs were manually (Manual-score) and automatically (Auto-score) scored by our designed algorithm. The agreement between Manual- and Auto-score was assessed by kappa statistics. Test set: ECGs from 199 STEMI patients were assigned a severity grade (severe or non-severe ischemia) by the Auto-score. Infarct size estimated by median peak Troponin T (TnT) and Creatinine Kinase Myocardial Band (CKMB) was tested between the groups.

RESULTS

The agreement between Manual- and Auto-score was 0.83 ((95% CI 0.55-1.00), p < 0.0001), sensitivity 75% and specificity 100%, PPV 100% and NPV 94.6%. In the test set 152 (76%) patients were male, mean age 61 ± 12 years. The Auto-score designated severe ischemia in 42 (21%) and non-severe ischemia in 157 (79%) patients. Patients with ECG signs of severe vs. non-severe ischemia had significantly higher levels of biomarkers of infarct size. In multiple linear regression, ECG sign of severe ischemia was an independent predictor for higher TnT and CKMB levels.

CONCLUSION

The automatic ECG algorithm for severity of ischemia in STEMI performs adequately for clinical use. Severe ischemia obtained by the Auto-score was associated with biomarker estimated larger infarct size.

Ischemic QRS prolongation as a biomarker of myocardial injury in STEMI patients

BACKGROUND

Patients with acute coronary occlusion (ACO) may not only have ischemia-related ST-segment changes but also changes in the QRS complex. It has recently been shown in dogs that a greater ischemic QRS prolongation (IQP) during ACO is related to lower collateral flow. This suggests that greater IQP could indicate more severe ischemia and thereby more rapid infarct development. Therefore, the purpose was to evaluate the relationship between IQP and measures of myocardial injury in patients presenting with acute ST-elevation myocardial infarction (STEMI).

METHODS

Seventy-seven patients with first-time STEMI were retrospectively included from the recently published SOCCER trial. All patients underwent a cardiac magnetic resonance (CMR) examination 2-6 days after the acute event. Infarct size (IS), myocardium at risk (MaR), and myocardial salvage index (MSI) were assessed and related to IQP. IQP measures assessed were; computer-generated QRS duration, QRS duration at maximum ST deviation, absolute IQP and relative IQP, all derived from a pre-PCI, 12-lead ECG.

RESULTS

Median absolute IQP was 10 ms (range 0-115 ms). There were no statistically significant correlations between measures of IQP and any of the CMR measures of myocardial injury (absolute IQP vs IS, r = 0.03, p = 0.80; MaR, r = -0.01, p = 0.89; MSI, r = -0.05, p = 0.68).

CONCLUSIONS

Unlike previous experimental studies, the IQP was limited in patients presenting at the emergency room with first-time STEMI and no correlation was found between IQP and CMR variables of myocardial injury in these patients. Therefore, IQP does not seem to be a suitable biomarker for triaging patients in this clinical context.

Electrocardiographic scores of severity and acuteness of myocardial ischemia predict myocardial salvage in patients with anterior ST-segment elevation myocardial infarction

BACKGROUND

Terminal "QRS distortion" on the electrocardiogram (ECG) (based on Sclarovsky-Birnbaum's Grades of Ischemia Score) is a sign of severe ischemia, associated with adverse cardiovascular outcome in ST-segment elevation myocardial infarction (STEMI). In addition, ECG indices of the acuteness of ischemia (based on Anderson-Wilkins Acuteness Score) indicate myocardial salvage potential. We assessed whether severe ischemia with or without acute ischemia is predictive of infarct size (IS), myocardial salvage index (MSI) and left ventricular ejection fraction (LVEF) in anterior versus inferior infarct locations.

METHODS

In STEMI patients, the severity and acuteness scores were obtained from the admission ECG. Based on the ECG patients were assigned with severe or non-severe ischemia and acute or non-acute ischemia. Cardiac magnetic resonance (CMR) was performed 2-6days after primary percutaneous coronary intervention (pPCI). LVEF was measured by echocardiography 30days after pPCI.

RESULTS

ECG analysis of 85 patients with available CMR resulted in 20 (23%) cases with severe and non-acute ischemia, 43 (51%) with non-severe and non-acute ischemia, 17 (20%) with non-severe and acute ischemia, and 5 (6%) patients with severe and acute ischemia. In patients with anterior STEMI (n=35), ECG measures of severity and acuteness of ischemia identified significant and stepwise differences in myocardial damage and function. Patients with severe and non-acute ischemia had the largest IS, smallest MSI and lowest LVEF. In contrast, no difference was observed in patients with inferior STEMI (n=50).

CONCLUSIONS

The applicability of ECG indices of severity and acuteness of myocardial ischemia to estimate myocardial damage and salvage potential in STEMI patients treated with pPCI, is confined to anterior myocardial infarction.

Diagnostic performance of T1 and T2 mapping to detect intramyocardial hemorrhage in reperfused ST-segment elevation myocardial infarction (STEMI) patients

Purpose

To investigate the performance of T₁ and T₂ mapping to detect intramyocardial hemorrhage (IMH) in ST‐segment elevation myocardial infarction (STEMI) patients treated by primary percutaneous coronary intervention (PPCI).

Materials and Methods

Fifty STEMI patients were prospectively recruited between August 2013 and July 2014 following informed consent. Forty‐eight patients completed a 1.5T cardiac magnetic resonance imaging (MRI) with native T₁, T₂, and T2* maps at 4 ± 2 days. Receiver operating characteristic (ROC) analyses were performed to assess the performance of T₁ and T₂ to detect IMH.

Results

The mean age was 59 ± 13 years old and 88% (24/48) were male. In all, 39 patients had interpretable T2* maps and 26/39 (67%) of the patients had IMH ( T2* <20 msec on T2* maps). Both T₁ and T₂ values of the hypointense core within the area‐at‐risk (AAR) performed equally well to detect IMH (T₁ maps AUC 0.86 [95% confidence interval [CI] 0.72–0.99] versus T₂ maps AUC 0.86 [95% CI 0.74–0.99]; P = 0.94). Using the binary assessment of presence or absence of a hypointense core on the maps, the diagnostic performance of T₁ and T₂ remained equally good (T₁ AUC 0.87 [95% CI 0.73–1.00] versus T₂ AUC 0.85 [95% CI 0.71–0.99]; P = 0.90) with good sensitivity and specificity (T₁: 88% and 85% and T₂: 85% and 85%, respectively).

Conclusion

The presence of a hypointense core on the T₁ and T₂ maps can detect IMH equally well and with good sensitivity and specificity in reperfused STEMI patients and could be used as an alternative when T2* images are not acquired or are not interpretable.

Level of Evidence: 2

Technical Efficacy: Stage 2

J. MAGN. RESON. IMAGING 2017;46:877–886

Pre-hospital electrocardiographic severity and acuteness scores predict left ventricular function in patients with ST elevation myocardial infarction

OBJECTIVES

System delay (time from first medical contact to primary percutaneous coronary intervention) is associated with heart failure and mortality in patients with ST segment elevation myocardial infarction (STEMI). We evaluated the impact of system delay on left ventricular function (LVF) according to the combination of ischemia severity (Sclarovsky-Birnbaum grades) and acuteness (Anderson-Wilkins scores) in the pre-hospital electrocardiogram (ECG).

METHODS

In a predefined secondary analysis of a prospective study, the severity and acuteness scores were performed on the pre-hospital ECG. Patients were assessed with respect to 4 classifications which were not mutually exclusive: severe ischemia (+SI) or non-severe ischemia (-SI) and acute ischemia (+AI) or non-acute ischemia (-AI). LVF was assessed by global longitudinal strain (GLS) within 48hours of admission. Adjusted linear regression investigated the association of system delay with GLS in each group.

RESULTS

In total 262 patients were eligible for analysis of the ECG, which resulted in 42 (16%) with (+SI, -AI), 110 (42%) with (-SI, -AI), 90 (34%) with (-SI, +AI), and 20 (8%) patients with (+SI, +AI). Although system delay did not differ between groups, patients with severe and non-acute ischemia had the most impaired LVF. System delay correlated weakly with GLS in the entire population (r=0.133, p=0.031), and well with GLS in the (+SI, +AI) group (r=0.456, p=0.04), while there was no correlation in the other groups. By adjusted analysis, system delay predicted impaired GLS only in the (+SI, +AI) group (β=0.578, p=0.002).

CONCLUSION

Pre-hospital risk stratification by ECG identifies patients with acute and severe ischemia who are at increased risk for reduced ventricular function (assessed by GLS) after STEMI. Optimizing reperfusion delays in these patients can therefore be of particular benefit in improving clinical outcome after STEMI.

QRS distortion in pre-reperfusion electrocardiogram is a bedside predictor of large myocardium at risk and infarct size (a METOCARD-CNIC trial substudy)

BACKGROUND

QRS distortion is an electrocardiographic (ECG) sign of severe ongoing ischemia in the setting of ST-segment elevation acute myocardial infarction (STEMI). We sought to evaluate the association between the degree of QRS distortion and myocardium at risk and final infarct size, measured by cardiac magnetic resonance (CMR).

METHODS

A total of 174 patients with a first anterior STEMI reperfused by primary angioplasty were prospectively recruited. Pre-reperfusion ECG was used to divide the study population into three groups according to the absence of QRS distortion (D0) or its presence in a single lead (D1) or in 2 or more contiguous leads (D2+). Myocardium at risk and infarct size were determined by CMR one week after STEMI. Multiple regression analysis was used to study the association of QRS distortion with myocardium at risk and infarct size, with adjustment for relevant clinical and ECG variables.

RESULTS

101 patients (58%) were in group D0, 30 (17%) in group D1, and 43 (25%) in group D2+. Compared with group D0, presence of QRS distortion (groups D2+ and D1) was associated with a significantly adjusted larger extent of myocardium at risk (group D2+: absolute increase 10.4%, 95% CI 6.1-14.8%, p<0.001; group D1: absolute increase 3.3%, 95% CI 1.3-7.9%, p=0.157) and larger infarct size (group D2+: absolute increase 10.1%, 95% CI 5.5-14.7%, p<0.001; group D1: absolute increase 4.9%, 95% CI 0.08-9.8%, p=0.046).

CONCLUSIONS

Distortion in the terminal portion of the QRS complex on pre-reperfusion ECG in two or more leads is independently associated with larger myocardium at risk and infarct size in the setting of primary angioplasty-reperfused anterior STEMI. QRS distortion in only one lead is independently associated with larger infarct size in this setting. Our findings suggest that QRS distortion analysis could be included in risk-stratification of patients presenting with anterior STEMI.

QRS complex distortion (Grade 3 ischaemia) as a predictor of myocardial damage assessed by cardiac magnetic resonance imaging and clinical prognosis in patients with ST-elevation myocardial infarction

AIMS

Distortion of the terminal portion of the QRS complex (so-called Grade 3 ischaemia, G3I) has been associated with adverse outcomes in ST-elevation myocardial infarction (STEMI) populations. However, the correlation of G3I with infarct size and microvascular injury as defined by cardiac magnetic resonance (CMR) is not well defined. Aim of this study was to assess the relation of G3I with myocardial damage as assessed by CMR and clinical outcomes in STEMI patients.

METHODS AND RESULTS

We analysed the ECGs of 572 consecutive STEMI patients regarding the presence or absence of G3I. CMR was performed within 1 week after infarction for comprehensive assessment of myocardial damage using a standardized protocol. The primary clinical endpoint was major adverse cardiac events (MACE) within 12 months after infarction. G3I was present in 186 (32%) patients. The presence of G3I was associated with larger infarct size (P = 0.01), the presence of late microvascular obstruction (P = 0.05), the presence of intramyocardial haemorrhage (P = 0.04), and impaired myocardial salvage (P = 0.01). G3I was associated with a higher incidence of MACE (P = 0.01) and was identified as an independent predictor of MACE in Cox regression analysis (HR 2.19; 95% CI 1.10 to 4.38, P = 0.03).

CONCLUSION

This largest study to date correlating G3I on the admission ECG with CMR markers of myocardial damage demonstrates that G3I is significantly associated with infarct size, impaired myocardial salvage, and reperfusion injury in a reperfused STEMI population. Moreover, G3I was independently associated with MACE. CLINICALTRIALS.GOV: NCT00712101.

Updated electrocardiographic classification of acute coronary syndromes

The electrocardiogram (ECG) findings in acute coronary syndrome should always be interpreted in the context of the clinical findings and symptoms of the patient, when these data are available. It is important to acknowledge the dynamic nature of ECG changes in acute coronary syndrome. The ECG pattern changes over time and may be different if recorded when the patient is symptomatic or after symptoms have resolved. Temporal changes are most striking in cases of ST-elevation myocardial infarction. With the emerging concept of acute reperfusion therapy, the concept ST-elevation/ non-ST elevation has replaced the traditional division into Q-wave/non-Q wave in the classification of acute coronary syndrome in the acute phase.

KEYPOINTS

In acute coronary syndrome, in addition to the traditional electrocardiographic risk markers, such as ST depression, the 12-lead ECG contains additional, important diagnostic and prognostic information. Clinical guidelines need to acknowledge certain high-risk ECG patterns to improve patient care.

Twenty years of ECG grading of the severity of ischemia

Shortly following an occlusion of an epicardial coronary artery, changes in the surface electrocardiogram (ECG) can be detected. Initially, T waves in leads with their positive poles facing the ischemic zone become positive, tall and symmetrical. Later, ST segment elevation (STE) becomes apparent. If ischemia continues, changes in the terminal portion of the QRS may also be detected. The changes in the terminal portion of the QRS are believed to be caused by prolongation of the electrical conduction in the ischemic zone and reflect severe ischemia due to lack of protection by preconditioning or collateral circulation. Several groups have shown that patients with the QRS changes of grade 3 ischemia have higher mortality, higher incidence of reinfarction and heart failure than patients presenting with only the T and ST changes of grade 2 ischemia, despite equal success in recanalizing the epicardial coronary artery by either thrombolytic therapy or primary percutaneous coronary intervention. Grade 3 ischemia is associated with more rapid progression of necrosis and larger final infarct size. Further studies are needed to better understand the underlying mechanisms that determine the severity of ischemia and how we should use this method based on the standard 12 lead ECG to implement clinical therapeutic decisions.

Relation of angiographic thrombus burden with electrocardiographic grade III ischemia in patients with ST-segment elevation myocardial infarction

BACKGROUND

We aimed to investigate the association between electrocardiographic (ECG) grade III ischemia and angiographic thrombus burden in patients with acute ST-segment elevation myocardial infarction (STEMI) who underwent primary percutaneous coronary intervention (pPCI).

METHODS

The study population consisted of 307 patients with STEMI. Baseline ECGs of the patients were analyzed for grade III ischemia; angiographic thrombus burden was assessed by thrombolysis in myocardial infarction thrombus classification.

RESULTS

A total of 108 (35%) patients had low thrombus burden whereas 199 (65%) patients had high thrombus burden. Grade III ischemia was more prevalent in patients with high thrombus burden (25.1% vs 11.1%, P = .004). Only grade III ischemia (odds ratio: 2.59, 95% confidence interval 1.24-5.39, P = .011) and history of coronary artery disease (CAD) were found to be the independent predictors of high thrombus burden.

CONCLUSION

Grade III ischemia on ECG and previous history of CAD were independent predictors of coronary thrombus burden in patients with STEMI who underwent pPCI.

The size does not matter - the presence of microvascular obstruction but not its extent corresponds to larger infarct size in reperfused STEMI

BACKGROUND

Microvascular obstruction (MVO) is a cardiac magnetic resonance (CMR) marker of no-reflow in ST-segment elevation myocardial infarction (STEMI). It remains unresolved whether the infarct size corresponds only to the presence of MVO or also to its extent.

METHODS

The study included 53 patients with first STEMI (median age 61.5 years, 77% male) treated with percutaneous coronary intervention (PCI) who underwent CMR after median 5 days from PCI. Small MVO was defined as patchy, non-confluent spots of dark areas of absent contrast surrounded by late gadolinium enhancement (LGE). Large MVO was defined as confluent areas of MVO comprising a large amount of the infarct zone.

RESULTS

Microvascular obstruction was observed in 32 patients (60%) including 18 patients with small MVO (36%) and 14 patients with large MVO (24%). Patients with MVO were more likely to have TIMI 0/1 grade flow on initial angiogram, higher levels of necrotic markers, larger infarct size, larger left ventricular end-diastolic and end-systolic volume and lower ejection fraction in comparison to patients without MVO. These differences were not observed between patients with large and small MVO.

CONCLUSIONS

The presence of MVO but not its extent corresponds to larger infarct size in STEMI.