Combined historical and electrocardiographic timing of acute anterior and inferior myocardial infarcts for prediction of reperfusion achievable size limitation

In-Hospital Prognostic Value of Electrocardiographic Parameters Other Than ST-Segment Changes in Acute Myocardial Infarction: Literature Review and Future Perspectives

Electrocardiography (ECG) remains an irreplaceable tool in the management of the patients with myocardial infarction, with evaluation of the QRS and ST segment being the present major focus. Several ECG parameters have already been proposed to have prognostic value with regard to both in-hospital and long-term follow-up of patients. In this review, we discuss various ECG parameters other than ST segment changes, particularly with regard to their in-hospital prognostic importance. Our review not only evaluates the prognostic segments and parts of ECG, but also highlights the need for an integrative approach in big data to re-assess the parameters reported to predict in-hospital prognosis. The evolving importance of artificial intelligence in evaluation of ECG, particularly with regard to predicting prognosis, and the potential integration with other patient characteristics to predict prognosis, are discussed.

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.

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.

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.

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.

The predictive value of an ECG-estimated Acute Ischemia Index for prognosis of myocardial salvage and infarct healing 3months following inferior ST-elevated myocardial infarction

BACKGROUND AND PURPOSE

Identification of prognostic markers can be used to stratify patients in the acute phase of ST-elevated myocardial infarction (STEMI) according to their potential to retain viable myocardium after reperfusion. The percentage of the myocardial area at risk (MaR) that is ischemic at admission, defined as the Acute Ischemia Index, is potentially salvageable. The percentage of the MaR viable at 3months post-reperfusion, by salvage and healing, was defined as the Chronic Salvage Index. A positive relationship between the Acute Ischemia Index and the Chronic Salvage Index was hypothesized.

METHODS

Both indices were assessed by using the ECG indices Aldrich ST and Selvester QRS scores estimating the ischemic and infarcted myocardium. The study population comprised inferior STEMI patients. (N=59).

RESULTS

A correlation of 0.253 (P=0.053) was found.

CONCLUSIONS

These results are relevant and suggest evidence of a trend in the association between these indices.

Infarct evolution in man studied in patients with first-time coronary occlusion in comparison to different species - implications for assessment of myocardial salvage

BACKGROUND

The time course of infarct evolution, i.e. how fast myocardial infarction (MI) develops during coronary artery occlusion, is well known for several species, whereas no direct evidence exists on the evolution of MI size normalized to myocardium at risk (MaR) in man. Despite the lack of direct evidence, current literature often refers to the "golden hour" as the time during which myocardial salvage can be accomplished by reperfusion therapy. Therefore, the aim of the present study was to investigate how duration of myocardial ischemia affects infarct evolution in man in relation to previous animal data. Consecutive patients with clinical signs of acute myocardial ischemia were screened and considered for enrollment. Particular care was taken to assure uniformity of the patients enrolled with regard to old MI, success of revascularization, collateral flow, release of biochemical markers prior to intervention etc. Sixteen patients were ultimately included in the study. Myocardium at risk was assessed acutely by acute myocardial perfusion single photon emission computed tomography (MPS) and by T2 imaging (T2-STIR) cardiovascular magnetic resonance (CMR) after one week in 10 of the 16 patients. Infarct size was measured by late gadolinium enhancement (LGE) at one week.

RESULTS

The time to reach 50% MI of the MaR (T50) was significantly shorter in pigs (37 min), rats (41 min) and dogs (181 min) compared to humans (288 min). There was no significant difference in T50 when using MPS compared to T2-STIR (p = 0.53) for assessment of MaR (288 +/- 23 min vs 310 +/- 22 min, T50 +/- standard error). The transmural extent of MI increased progressively as the duration of ischemia increased (R2 = 0.56, p < 0.001).

CONCLUSION

This is the first study to provide direct evidence of the time course of acute myocardial infarct evolution in relation to MaR in man with first-time MI. Infarct evolution in man is significantly slower than in pigs, rats and dogs. Furthermore, infarct evolution assessments in man are similar when using MPS acutely and T2-STIR one week later for determination of MaR, which significantly facilitates future clinical trials of cardioprotective therapies in acute coronary syndrome by the use of CMR.

Timing of ischemic onset estimated from the electrocardiogram is better than historical timing for predicting outcome after reperfusion therapy for acute anterior myocardial infarction: a DANish trial in Acute Myocardial Infarction 2 (DANAMI-2) substudy

BACKGROUND

Acute treatment strategy and subsequently prognosis are influenced by the duration of ischemia in patients with ST-elevation acute myocardial infarction (AMI). However, timing of ischemia may be difficult to access by patient history (historical timing) alone. We hypothesized that an electrocardiographic acuteness score is better than historical timing for predicting myocardial salvage and prognosis in patients with anterior AMI treated with fibrinolysis or primary percutaneous coronary intervention.

METHODS

One hundred seventy-five patients with anterior infarct without electrocardiogram (ECG) confounding factors were included. The ECG method for estimating timing of AMI was calculated using core laboratory measurements from the initial 12-lead ECG. Historical timing was recorded as time from symptom onset to initiation of reperfusion therapy. Myocardial salvage was determined by ECG, using the Aldrich score to determine the initially predicted myocardial infarct size and the Selvester score to determine the final QRS-estimated myocardial infarct size.

RESULTS

The mean amount of myocardium salvage depended on ECG timing (43% [+/-38%] for "early" vs 1% [+/-56%] for "late"; P < .001), whereas myocardial salvage was independent of historical timing (P = .9). One-year mortality was predicted from ECG timing (P = .04).

CONCLUSIONS

The ECG method of timing was superior to historical timing in predicting myocardial salvage and prognosis after reperfusion therapy. This study suggests that ECG estimated duration of ischemia might provide a better and objective means to select acute reperfusion therapy rather than the subjective patient history, which could preclude proper reperfusion in some patients with salvageable myocardium.

Electrocardiogram dynamics for risk stratification in ST-segment elevation myocardial infarction—immediate and serially updated information on outcome

Early and serially updated predictions of final infarct-size and clinical outcome--before, during and after reperfusion treatment of ST-elevation myocardial infarction might allow a more individualized treatment: High-risk patients with a predicted major loss of viable myocardium can be identified immediately or during therapy, at a stage when treatment may still be modified; and low-risk patients with predictions of small infarcts and good outcome already after standard primary reperfusion therapy can be identified and thereby avoid a possibly harmful intensified treatment. The necessary information for such predictions seem to be available from the standard 12-lead ECG and from ST-segment monitoring. Today this information, however, is not readily available in clinical practice. Automated algorithms need to be engineered for a broader use and for possibilities of a refined triage and thus for a more individualized strategy of reperfusion therapy.

Acute coronary syndromes

Despite technologic advances in many diagnostic fields, the 12-lead ECG remains the basis for early identification and management of an acute coronary syndrome. This article reviews the use of the ECG in acute coronary syndromes.

Electrocardiogram of acute ST-elevation myocardial infarction: the significance of the various "scores"

The Electrocardiogram has extensively been used for evaluation and triage of patients with acute chest pain. The clinician admitting a patient with ST elevation acute myocardial infarction should be able to estimate the size and location of the ischemic area at risk, how much of the ischemic myocardium has already undergone irreversible necrosis by the time of presentation, and the "severity of ischemia" (or what is the rate of progression of necrosis as long as ischemia continues). The electrocardiographic variables that are used to make these estimates are the initial portion of the QRS (Q and R waves), the terminal portion of the QRS (the S waves and the J-point), the ST segment, and the configuration of the T waves. This editorial discuss the ability to predict each of the "physiological" parameters using the above mentioned electrocardiographic variables.

A dynamic model forecasting myocardial infarct size before, during, and after reperfusion therapy: an ASSENT-2 ECG/VCG substudy

AIMS

Serial forecasts of final myocardial infarct (MI) size during fibrinolytic treatment (Rx) of ST-elevation MI would allow the identification of high-risk patients with a predicted major loss of viable myocardium, at a point when treatment may still be modified. We investigated a model for such forecasting, using time and the ECG.

METHODS AND RESULTS

We collected 234 patients with ST-elevation MI, without signs of previous MI, bundle branch block, or hypertrophy. MI size was determined by the Selvester score and was "forecasted" at: admission with patients stratified by delay time and an ECG acuteness score into three groups (EARLY, DISCORDANT, and LATE); 90 min after Rx by > or =70% ST-recovery or not and occurrence of "reperfusion peaks"; 4 h after Rx by ST re-elevations. EARLY patients had smaller final infarct sizes than LATE (9.4 vs. 20%, P=0.01). EARLY patients with > or =70% ST-recovery without a reperfusion peak had smaller infarct sizes than those with (3.1 vs. 12.5%, P=0.001). EARLY patients without ST re-elevations had smaller infarct sizes (1.5%) than those with some (9%) or many re-elevations (12%), P<0.001.

CONCLUSION

Final infarct size can be forecasted using delay time and serial ECGs. Serially updated forecasts seem especially important when both clock-time and initial ECG- signs indicate earliness.

Comparison between human and automated electrocardiographic waveform measurements for calculating the Anderson-Wilkins acuteness score in patients with acute myocardial infarction

The Anderson-Wilkins (AW) electrocardiographic (ECG) acuteness score complements time from pain onset in prognostic stratification of patients with acute myocardial infarction (AMI). However, for the AW acuteness score to be of practical use in the acute situation, it must be an integral component of a commercial automated ECG analysis program. The objective of this study was to determine the concordance between human and computer measurements and calculation of the AW acuteness score. The mean difference in AW acuteness score was 0.11 +/- 0.66 for anterior and -0.07 +/- 1.24 for inferior AMI. Ninety-nine percent of the differences were found to be 1.0 or less for the anterior AMI group, and 91.7% were 1.0 or less in the inferior AMI group. The differences were primarily caused by minor disagreements in measurements. In conclusion, the AW acuteness score established using manual ECG waveform measurements can be implemented into commercial automated ECG analysis programs to achieve practical use in clinical decision support for patients with AMI.

Refinement and interobserver agreement for the electrocardiographic Sclarovsky-Birnbaum Ischemia Grading System

BACKGROUND

Electrocardiogram-derived grades of ischemia at the time of patient presentation with acute myocardial infarction have proved useful in predicting the salvageability by reperfusion therapy, final infarct size, severity of left ventricular dysfunction, and short- and long-term prognosis.

SUBJECTS AND METHODS

The Sclarovsky-Birnbaum Ischemia Grading System based on the relation between the acute appearances of the T wave, the ST segment, and the QRS complex was considered as a means of enhanced ECG analysis in this group of patients. The evaluation of a training population (n = 46) resulted in refinement of the published description of the Sclarovsky-Birnbaum Ischemia Grading System, and a test population (n = 50) was utilized for investigating the interobserver agreement among 5 observers in determining the grade of ischemia.

RESULTS

The agreement among the observers applying the "refined" Sclarovsky-Birnbaum Ischemia Grading System was 0.89. Complete agreement was found for the ECGs of 80% of the patients, and the most common reason for disagreement was the application of the terminal T-negativity criterion.

CONCLUSIONS

The refined Sclarovsky-Birnbaum Ischemia Grading System can be performed manually with low interobserver variability. It has potential for support of the acute myocardial infarction triage decision as an electrocardiographic method for evaluating the level of ischemic protection at the time of either pre-hospital or emergency-department presentation.

A modified Anderson-Wilkins electrocardiographic acuteness score for anterior or inferior myocardial infarction

BACKGROUND

Optimal treatment of acute myocardial infarction (AMI) depends on the duration of the ischemia. The Anderson Wilkins (AW) electrocardiographic acuteness score has been shown to complement the historical timing in estimating the time interval from acute thrombotic coronary occlusion in patients presenting with chest pain and evolving myocardial infarction. The purposes of this study were to (1) compare the distributions of the previously developed AW acuteness score in a training population with either anterior or inferior AMI and (2) propose modifications to the formula to achieve distributions similar to the observed distributions of historical times from onset of pain.

METHODS

Two hundred three and 177 patients were included as training and testing population, respectively. All patients had an anterior or an inferior AMI and were without confounding factors on the electrocardiogram.

RESULTS

The training population had similar distributions of historical times from onset of pain, but differences in distributions of AW acuteness scores, between patients with anterior and inferior AMI (P <.0001). Eighty percent of the inferior AMI group had the highest possible AW acuteness score. Modification of a Q-wave criterion from > or =30 to > or =20 ms resulted in similar distributions in patients with anterior and inferior AMI both in the training and an independent testing population.

CONCLUSIONS

These results suggest that a modified AW acuteness score using a lower Q-wave duration criterion provides similar AMI timing information in patients with anterior and inferior locations. Clinical use of the AW acuteness score will only be practical if the calculation is automated.