Acute myocardial infarction due to left circumflex artery occlusion and significance of ST-segment elevation

Early ischemic ST-segment and T-wave changes during balloon angioplasty

BACKGROUND

Acute coronary occlusion results in increased T-wave amplitude and ST-segment elevation in the ECG leads facing the ischemic region.

MATERIAL AND METHODS

We performed continuous ECG recording in 34 patients during balloon occlusion of the left anterior descending (LAD), left circumflex (LCx) and right coronary artery (RCA). Delta (Δ) ST and ΔT amplitudes were calculated by subtracting the preinflation values from the values measured during balloon inflation.

RESULTS

Occlusion of the LAD resulted in greater increase in the amplitude of the T wave than of the ST segment in lead V2 (ΔT +3.4 mm, inter-quartile range [IQR] 1-6 mm; ΔST +1.4 mm, 0.5-3 mm). During RCA occlusion, ΔST and ΔT didn't differ significantly. LCx occlusion resulted in significant differences between ΔST and ΔT in all leads, except aVF and V3-V4. In two patients (LCx), we observed a biphasic ST-T response: an initial negative change of the T-wave amplitude was followed by a positive change in leads V1-V2. In leads II, III, aVF and V4-V6, there was an initial positive change, followed by a final negative change towards the end of the occlusion.

CONCLUSION

Continuous 12‑lead ECG recording during balloon occlusion of the LCx resulted in significant differences between the ΔST and ΔT values in all leads except aVF and V3-V4. LAD and RCA occlusion resulted in less evident differences between the ST-segment and T-wave changes. A change in polarity of T-wave changes during balloon occlusion (initial negative and final positive change, or vice versa) proved to be a rare finding.

Practical Aspects of the Use of Telematic Systems in the Diagnosis of Acute Coronary Syndrome in Poland

Background and Objectives: The guidelines of the European Society of Cardiology (ESC) recommend the use of telematic methods in the diagnosis of myocardial infarction, allowing for transtelephonic electrocardiography (TTECG) from the emergency scene to centers performing percutaneous coronary interventions (PCI center). It has been proven that such a procedure has a beneficial effect on the survival of patients with ST elevation myocardial infarction (STEMI). Fewer data can be found on the correct use of these methods in everyday clinical practice. The aim of this study was to indicate potential indications and contraindications for the use of the TTECG system, and provide recommendations for proper collaboration between emergency medical systems (EMS) teams and PCI centers. Materials and Methods: The article is a systematic review of cardiological emergencies, with an assessment of indications for the use of the TTECG system. The authors introduced their own grading of the validity of indications for transmission of the TTECG, similar to those used in the official ESC guidelines.: Results:: The authors described individual cardiological emergencies occurring in the practice of EMS, considering specific indications or contraindications for the transmission of the TTECG. The article also discusses individual practical recommendations for proper cooperation between EMS teams and PCI centers in detail. All of the recommendations are compiled in a handy table to facilitate its use in everyday clinical practice. Conclusions: The summary presents a comparison of the realities of the functioning of the telematic support system in Poland in the field of STEMI diagnostics, with the model’s recommendations. The necessity of further educating the members of individual teams included in the network dealing with STEMI treatment was indicated, as well as the necessity of introducing legal regulations sanctioning the functioning of telematic systems in modern medicine.

Cardiogenic shock complicating non-ST-segment elevation myocardial infarction: An 18-year study

OBJECTIVE

To evaluate the epidemiology and outcomes of non-ST-segment-elevation myocardial infarction-cardiogenic shock (NSTEMI-CS) in the United States.

METHODS

Adult (>18 years) NSTEMI-CS admissions were identified using the National Inpatient Sample (2000-2017) and classified by tertiles of admission year (2000-2005, 2006-2011 and 2012-2017). Outcomes of interest included temporal trends of prevalence and in-hospital mortality, use of cardiac procedures, in-hospital mortality, hospitalization costs, and length of stay.

RESULTS

In over 7.3 million NSTEMI admissions, CS was noted in 189,155 (2.6%). NSTEMI-CS increased from 1.5% in 2000 to 3.6% in 2017 (adjusted odds ratio 2.03 [95% confidence interval 1.97-2.09]; P < .001). Rates of non-cardiac organ failure and cardiac arrest increased during the study period. Between 2000 and 2017, coronary angiography (43.9%-63.9%), early coronary angiography (13.6%-25.6%), percutaneous coronary intervention (14.8%-31.6%), and coronary artery bypass grafting use (19.0%-25.8%) increased (P < .001). Over the study period, the use of intra-aortic balloon pump remained stable (28.6%-28.8%), and both percutaneous left ventricular assist devices (0%-9.1%) and extra-corporeal membrane oxygenation (0.1%-1.6%) increased (all P < .001). In hospital mortality decreased from 50.2% in 2000 to 32.3% in 2017 (adjusted odds ratio 0.27 [95% confidence interval 0.25-0.29]; P < .001). During the 18-year period, hospital lengths of stay decreased, and hospitalization costs increased.

CONCLUSIONS

In the United States, prevalence of CS in NSTEMI has increased 2-fold between 2000 and 2017, while in-hospital mortality has decreased during the study period. Use of coronary angiography and percutaneous coronary intervention increased during the study period.

Ischemic ST-Segment Depression Maximal in V1-V4 (Versus V5-V6) of Any Amplitude Is Specific for Occlusion Myocardial Infarction (Versus Nonocclusive Ischemia)

Background Occlusion myocardial infarctions (OMIs) of the posterolateral walls are commonly missed by ST-segment-elevation myocardial infarction (STEMI) criteria, with >50% of patients with circumflex occlusion not receiving emergent reperfusion and experiencing increased mortality. ST-segment depression maximal in leads V1-V4 (STDmaxV1-4) has been suggested as an indicator of posterior OMI. Methods and Results We retrospectively reviewed a high-risk population with acute coronary syndrome. OMI was defined from prior studies as a culprit lesion with TIMI (Thrombolysis in Myocardial Infarction) 0 to 2 flow or TIMI 3 flow plus peak troponin T >1.0 ng/mL or troponin I >10 ng/mL. STEMI was defined by the Fourth Universal Definition of Myocardial Infarction. ECGs were interpreted blinded to outcomes. Among 808 patients, there were 265 OMIs, 108 (41%) meeting STEMI criteria. A total of 118 (15%) patients had "suspected ischemic" STDmaxV1-4, of whom 106 (90%) had an acute culprit lesion, 99 (84%) had OMI, and 95 (81%) underwent percutaneous coronary intervention. Suspected ischemic STDmaxV1-4 had 97% specificity and 37% sensitivity for OMI. Of the 99 OMIs detected by STDmaxV1-4, 34% had <1 mm ST-segment depression, and only 47 (47%) had accompanying STEMI criteria, of which 17 (36%) were identified a median 1.00 hour earlier by STDmaxV1-4 than STEMI criteria. Despite similar infarct size, TIMI flow, and coronary interventions, patients with STEMI(-) OMI and STDmaxV1-4 were less likely than STEMI(+) patients to undergo catheterization within 90 minutes (46% versus 68%; P=0.028). Conclusions Among patients with high-risk acute coronary syndrome, the specificity of ischemic STDmaxV1-4 was 97% for OMI and 96% for OMI requiring emergent percutaneous coronary intervention. STEMI criteria missed half of OMIs detected by STDmaxV1-4. Ischemic STDmaxV1-V4 in acute coronary syndrome should be considered OMI until proven otherwise.

Acute Total Occlusion of the Left Circumflex Coronary Artery Presenting with Non-ST-segment Elevation Myocardial Infraction and Normal Electrocardiogram – A Case Report

Introduction In this case report, we report a patient with non-ST-segment elevation myocardial infarction (NSTEMI), presenting with recurrent chest pain typical of angina, a very high troponin I level despite normal electrocardiogram (ECG). On angiography, it turns out that the patient has acute total occlusion in the left circumflex artery (LCx). Case Report A 56 years-old woman presented to the emergency department with chief complaint of recurrent chest pain typical of angina 20 hours before admission. Vital signs were within normal limit. There were no murmur, additional heart sounds, and no rales or crackles. The ECG showed normal sinus rhythm, and there were no ST-T changes on serial examination. The first and second cardiac enzymes troponin I was high (> 10 mg/L). Chest X-ray examination showed cardiomegaly without signs of lung edema.  Patient was diagnosed with high risk NSTEMI, hypertensive heart disease, and diabetes mellitus. Coronary showed an acute total occlusion in the LCx, which is determined as the culprit lesion for the ongoing myocardial infarction. A drug-eluting stent was deployed at the culprit lesion and the coronary flow was TIMI Flow 3. There was non-significant stenosis at the mid-right coronary artery. The echocardiography showed reduced left ventricular systolic function (LVEF 50%) with hypokinetic inferior-septal and inferior-lateral segment base to apical. Post-procedural follow-up was uneventful. Conclusion One of the learning points is that ECG may fail to detect acute total occlusion and rise in troponin level, despite the absence of ST-T changes, warrant urgent invasive strategy.

Electrocardiographic Diagnosis of Acute Coronary Occlusion Myocardial Infarction in Ventricular Paced Rhythm Using the Modified Sgarbossa Criteria

STUDY OBJECTIVE

Ventricular paced rhythm is thought to obscure the electrocardiographic diagnosis of acute coronary occlusion myocardial infarction. Our primary aim was to compare the sensitivity of the modified Sgarbossa criteria (MSC) to that of the original Sgarbossa criteria for the diagnosis of occlusion myocardial infarction in patients with ventricular paced rhythm.

METHODS

In this retrospective case-control investigation, we studied adult patients with ventricular paced rhythm and symptoms of acute coronary syndrome who presented in an emergency manner to 16 international cardiac referral centers between January 2008 and January 2018. The occlusion myocardial infarction group was defined angiographically as thrombolysis in myocardial infarction grade 0 to 1 flow or angiographic evidence of coronary thrombosis and peak cardiac troponin I ≥10.0 ng/mL or troponin T ≥1.0 ng/mL. There were 2 control groups: the "non-occlusion myocardial infarction-angio" group consisted of patients who underwent coronary angiography for presumed type I myocardial infarction but did not meet the definition of occlusion myocardial infarction; the "no occlusion myocardial infarction" control group consisted of randomly selected emergency department patients without occlusion myocardial infarction.

RESULTS

There were 59 occlusion myocardial infarction, 90 non-occlusion myocardial infarction-angio, and 102 no occlusion myocardial infarction subjects (mean age, 72.0 years; 168 [66.9%] men). For the diagnosis of occlusion myocardial infarction, the MSC were more sensitive than the original Sgarbossa criteria (sensitivity 81% [95% confidence interval [CI] 69 to 90] versus 56% [95% CI 42 to 69]). Adding concordant ST-depression in V4 to V6 to the MSC yielded 86% (95% CI 75 to 94) sensitivity. For the no occlusion myocardial infarction control group of ED patients, additional test characteristics of MSC and original Sgarbossa criteria, respectively, were as follows: specificity 96% (95% CI 90 to 99) versus 97% (95% CI 92 to 99); negative likelihood ratio (LR) 0.19 (95% CI 0.11 to 0.33) versus 0.45 (95% CI 0.34 to 0.65); and positive LR 21 (95% CI 7.9 to 55) versus 19 (95% CI 6.1 to 59). For the non-occlusion myocardial infarction-angio control group, additional test characteristics of MSC and original Sgarbossa criteria, respectively, were as follows: specificity 84% (95% CI 76 to 91) versus 90% (95% CI 82 to 95); negative LR 0.22 (95% CI 0.13 to 0.38) versus 0.49 (95% CI 0.35 to 0.66); and positive LR 5.2 (95% CI 3.2 to 8.6) versus 5.6 (95% CI 2.9 to 11).

CONCLUSION

For the diagnosis of occlusion myocardial infarction in the presence of ventricular paced rhythm, the MSC were more sensitive than the original Sgarbossa criteria; specificity was high for both rules. The MSC may contribute to clinical decisionmaking for patients with ventricular paced rhythm.

Prevalence and prognosis of isolated posterior ST-segment elevation acute myocardial infarction using synthesized-V7-9 lead

Limited data exist on the prevalence and prognosis of isolated posterior ST-segment elevation acute myocardial infarction (STEMI), revealed with a posterior chest lead. Furthermore, the utility of a synthesized-V_7-9 lead in the diagnosis of STEMI is unclear; therefore, we aimed to evaluate its usefulness. We enrolled 142 consecutive patients with STEMI with the culprit lesion on the left circumflex artery (STEMI-LCx) undergoing percutaneous coronary intervention (PCI) between January 2009 and December 2019. We retrospectively checked the ST-segment change of both standard 12-lead and synthesized-V_7-9 lead in all patients with STEMI-LCx. Based on electrocardiogram (ECG) findings, isolated posterior STEMI that was only revealed in synthesized-V_7-9 lead was classified as "STEMI-LCx-synV_7-9" and the remaining as "STEMI-LCx-12ECG." The prevalence of STEMI-LCx-synV_7-9 in patients with STEMI-LCx was assessed. The incidence of all-cause death, cardiac death, and mechanical complications within 30 days, 3 months, and 1 year was also assessed according to each STEMI-LCx. STEMI-LCx-synV_7-9 and STEMI-LCx-12ECG occurred in 10 (7.0%) and 132 (93.0%) patients, respectively. No significant difference was found in patients' characteristics between the two groups. The patients with STEMI-LCx-synV_7-9 had significantly higher incidences of cardiac death within 3 months and 1 year (30.0% vs. 6.1%, P = 0.031, 30.0% vs. 7.6%, P = 0.050, respectively) and mechanical complications in each follow-up period (20.0% vs. 1.5%, P = 0.025) than those with STEMI-LCx-12ECG. STEMI-LCx-synV_7-9 was observed in 7.0% of the patients with STEMI-LCx. Our findings suggest that the synthesized-V_7-9 lead helps diagnose isolated posterior STEMI and might improve prognosis in patients with STEMI-LCx.

Sharing and Teaching Electrocardiograms to Minimize Infarction (STEMI): reducing diagnostic time for acute coronary occlusion in the emergency department

BACKGROUND

Limits to ST-Elevation Myocardial Infarction (STEMI) criteria may lead to prolonged diagnostic time for acute coronary occlusion. We aimed to reduce ECG-to-Activation (ETA) time through audit and feedback on STEMI-equivalents and subtle occlusions, without increasing Code STEMIs without culprit lesions.

METHODS

This multi-centre, quality improvement initiative reviewed all Code STEMI patients from the emergency department (ED) over a one-year baseline and one-year intervention period. We measured ETA time, from the first ED ECG to the time a Code STEMI was activated. Our intervention strategy involved a grand rounds presentation and an internal website presenting weekly local challenging cases, along with literature on STEMI-equivalents and subtle occlusions. Our outcome measure was ETA time for culprit lesions, our process measure was website views/visits, and our balancing measure was the percentage of Code STEMIs without culprit lesions.

RESULTS

There were 51 culprit lesions in the baseline period, and 64 in the intervention period. Median ETA declined from 28.0 min (95% confidence interval [CI] 15.0-45.0) to 8.0 min (95%CI 6.0-15.0). The website garnered 70.4 views/week and 27.7 visitors/week in a group of 80 physicians. There was no change in percentage of Code STEMIs without culprit lesions: 28.2% (95%CI 17.8-38.6) to 20.0% (95%CI 11.2-28.8%). Conclusions Our novel weekly web-based feedback to all emergency physicians was associated with a reduction in ETA time by 20 min, without increasing Code STEMIs without culprit lesions. Local ECG audit and feedback, guided by ETA as a quality metric for acute coronary occlusion, could be replicated in other settings to improve care.

Effects of atorvastatin and ticagrelor combination therapy on renal function and the levels of suppression of tumorigenicity 2 and interleukin-33 in patients with ST-segment elevation myocardial infarction

OBJECTIVE

We evaluated the effects of atorvastatin and ticagrelor combination therapy on renal function and the levels of suppression of tumorigenicity 2 (ST2) and interleukin 33 (IL-33) in patients with ST-segment elevation myocardial infarction (STEMI).

METHODS

Eighty-four STEMI patients who underwent emergency percutaneous coronary intervention at our hospital from January 2015 to March 2018 were retrospectively analyzed and divided into a control group (n = 44) and an observation group (n = 40). The control group was treated with atorvastatin as routine STEMI treatment, whereas the observation group was concurrently administered ticagrelor.

RESULTS

After treatment, significantly better outcomes were observed in the control group than in the observation group in terms of clinical indices, including chest pain relief, enzyme levels, duration of reperfusion-associated arrhythmia, and depression of the ST segment. Both groups exhibited improvements in cardiac ultrasound indices, whereas the observation group showed lower left ventricular end-diastolic and end-systolic diameters and higher left ventricular ejection fractions than the control group.

CONCLUSIONS

Atorvastatin and ticagrelor combination therapy is clinically effective and safe for STEMI patients as it reduces the degree of myocardial infarction, protects the heart and renal functions, improves inflammation, and reduces adverse cardiac event incidences.

Urgent Pericardiocentesis Is More Frequently Needed After Left Circumflex Coronary Artery Perforation

Background: Coronary artery perforation (CAP) is a rare but potentially life-threatening complication of percutaneous coronary interventions (PCIs) due to the risk of cardiac tamponade. Strikingly, in contrast to numerous analyses of CAP predictors, only few studies were focused on the predictors of tamponade after PCI, once iatrogenic CAP has occurred. Our aim was to search for clinical and periprocedural characteristics, including the coronary artery involved, associated with the development of acute cardiac tamponade among patients experiencing CAP. Methods: From the medical records of nine centers of invasive cardiology in southern Poland, we retrospectively selected 81 patients (80% with acute myocardial infarction) who had iatrogenic CAP with a visible extravasation jet during angiography (corresponding to type III CAP by the Ellis classification, CAP_III) over a 15-year period (2005-2019). Clinical, angiographic and periprocedural characteristics were compared between the patients who developed acute cardiac tamponade requiring urgent pericardiocentesis in the cathlab (n = 21) and those with CAP_III and without tamponade (n = 60). Results: CAP_III were situated in the left anterior descending artery (LAD) or its diagonal branches (51%, n = 41), right coronary artery (RCA) (24%, n = 19), left circumflex coronary artery (LCx) (16%, n = 13), its obtuse marginal branches (7%, n = 6) and left main coronary artery (2%, n = 2). Acute cardiac tamponade occurred in 24% (10 of 41), 21% (4 of 19) and 37% (7 of 19) patients who experienced CAP_III in the territory of LAD, RCA and LCx, respectively. There were no significant differences in the need for urgent pericardiocentesis (37%) in patients with CAP_III in LCx territory (i.e., the LCx or its obtuse marginal branches) compared to CAP_III in the remaining coronary arteries (23%) (p = 0.24). However, when CAP_III in the LCx were separated from CAP_III in obtuse marginal branches, urgent pericardiocentesis was more frequently performed in patients with CAP_III in the LCx (54%, 7 of 13) compared to subjects with CAP_III in an artery other than the LCx (21%, 14 of 68) (p = 0.03). The direction of this tendency remained consistent regardless of CAP management: prolonged balloon inflation only (n = 26, 67% vs. 13%, p = 0.08) or balloon inflation with subsequent stent implantation (n = 55, 50% vs. 24%, p = 0.13). Besides LCx involvement, no significant differences in other characteristics were observed between patients according to the need of urgent pericardiocentesis. Conclusions: CAP_III in the LCx appears to lead to a higher risk of acute cardiac tamponade compared to perforations involving other coronary arteries. This association may possibly be linked to distinct features of LCx anatomy and/or well-recognized delays in diagnosis and management of LCx-related acute coronary syndromes.

Brain natriuretic peptide levels predict 6-month mortality in patients with cardiogenic shock who were weaned off extracorporeal membrane oxygenation

There are limited data regarding the association between brain natriuretic peptide (BNP) levels obtained after weaning from extracorporeal membrane oxygenation (ECMO) and the outcomes of patients with acute coronary syndrome (ACS)-associated cardiogenic shock.We prospectively obtained data regarding patients (aged ≥ 19 years) with ACS-associated cardiogenic shock who received ECMO and were subsequently weaned off the treatment. BNP levels were collected at 5 time points: pre-ECMO implantation, post-ECMO implantation, pre-ECMO weaning, day 1 after ECMO weaning, and day 5 after ECMO weaning.Of 48 patients with ACS-related cardiogenic shock, 33 were included in this analysis. Mean patient age was 59.0 (50.0-66.5) years, and 5 patients (15.2%) were women. Eight patients had asystole/pulseless electrical activity before ECMO and 14 (42.4%) had 3-vessel disease on coronary angiography. During the 6-month follow up, 12 (36.4%) patients died. BNP levels after ECMO weaning were significantly different between 6-month survivors and non-survivors. Cox proportional hazards model revealed that BNP levels (tertiles) on days 1 and 5 after ECMO weaning were significantly associated with 6-month mortality (hazard ratio, 7.872; 95% confidence interval, 1.870-32.756; 8.658 and 1.904-39.365, respectively). According to the Kaplan-Meier curves, the first tertile had significantly longer survival compared to the third tertile for both days 1 and 5 after ECMO weaning.Post-ECMO weaning BNP levels (days 1 and 5) were significantly associated with increased 6-month mortality in patients with ACS complicated by refractory cardiogenic shock who were weaned off ECMO.

Door-to-balloon time and cardiac mortality in acute myocardial infarction by total occlusion of the left circumflex artery

BACKGROUND

Acute myocardial infarction (AMI) caused by total occlusion of the left circumflex artery (LCX) can present as non-ST-segment elevation myocardial infarction (NSTEMI). We evaluate whether door-to-balloon time (DBT) is associated with cardiac mortality in patients with total occlusion of the LCX.

PATIENTS AND METHODS

From the Korea Acute Myocardial Infarction Registry, patients with AMI who had total occlusion with a Thrombolysis In Myocardial Infarction flow grade of 0 were included. We determined the factors for delay in primary percutaneous coronary intervention (DBT>90 min) and evaluated cardiac mortality for a median period of 14 months.

RESULTS

Mean DBT was 68 min (interquartile range=50-156 min), and the achievement rate of DBT less than or equal to 90 min was 66.9% in the entire study population. More than half of patients with total occlusion of LCX were presented as NSTEMI (57.7%). Among patients with total occlusion of the LCX, the mean DBT was 136 min (interquartile range=60-484 min), and the achievement rate of DBT less than or equal to 90 min was 42.8%. On multivariate analysis, LCX occlusion was an important factor for DBT more than 90 min (odds ratio: 1.766, P<0.001). Among patients with LCX occlusion, cardiac mortality was higher in patients with ST-segment elevation (6.2 vs. 11.0%, P=0.024).

CONCLUSION

This study showed that LCX occlusion was a significant factor for the delay in primary percutaneous coronary intervention on account of presenting as NSTEMI. Cardiac mortality was not associated with DBT more than 90 min but with ST-segment elevation in AMI patients with total occlusion of the LCX.

Submitral Aneurysm in a Patient with a Normal Electrocardiogram

A ventricular aneurysm entails well-known risks for the patient such as heart failure, potentially lethal arrhythmias, and systemic embolic phenomena. The submitral or posterolateral ventricular aneurysm is a very rare variety, usually of congenital etiology, which may also have other causes, including ischemic heart disease. The present case is about a 76-year-old male with the antecedent of an acute myocardial infarction 3 years ago. He presented with intermittent, brief, and self-limiting episodes of severe dyspnea, intense desperation, and accelerated palpitations, with a nonspecific electrocardiogram. An echocardiography revealed a large submitral aneurysm, with a good clinical response to the specific treatment of heart failure, antiarrhythmics, and oral anticoagulation therapy. We analyze the implications of an aneurysm in the context of an ischemic etiology, with special attention to the limitations of the electrocardiogram in the diagnosis of occlusions of the circumflex artery that irrigates the posterolateral region of the heart. We suspect that a greater number of patients with a culprit circumflex artery could receive appropriate coronary interventionism or thrombolysis if decision-making in the emergency room would not depend mainly on the electrocardiogram. Better stratification tools are needed to prevent late complications of infarction, such as those observed in this patient.

Comparison of Outcomes and Intervention Among Patients With Non-ST-Segment Elevation Acute Myocardial Infarction of Those With a Left Circumflex Versus Those With a Non-Left Circumflex-Related Coronary Artery (From the ELISA-3 Trial)

Previous studies found that patients with an acute coronary syndrome (ACS) due to occlusion of the left circumflex (LC) coronary artery often present without ST-elevation, leading to a delay in diagnosis and revascularization, a larger infarct size, and a worse prognosis. In this subgroup analysis of the ELISA-3 study (early or late intervention in high-risk non-ST-segment elevation acute coronary syndromes [NSTE-ACS]) incidence, characteristics and prognosis of LC-related NSTE-ACS was investigated, and the outcome of early versus late invasive strategy was compared. In 383 of 542 patients the culprit vessel could be identified, with the LC artery in 112 (29%) of them. Patients with LC-related ACS had more often single vessel disease and underwent percutaneous coronary intervention more and CABG less frequently. The primary end point of the combined incidences of death, myocardial infarction, and recurrent ischemia at 30-day follow-up occurred in 9.0% of LC versus 16.5% of non-LC-related ACS (p = 0.057). Enzymatic infarct size and incidence of bleeding were comparable. Of patients with LC-related ACS, 62 were assigned to an early and 50 to a late invasive treatment with a median time from admission to angiography of 5.5 and 65.7 hours, respectively. The primary end point occurred in 9.7% and 8.0%, respectively (p = 1.00) with comparable enzymatic infarct size and bleeding. In conclusion, no significant differences in outcome were found between patients with an LC- and a non-LC-related NSTE-ACS. In LC-related NSTE-ACS, angiography within 12 hours of admission is feasible but not superior to angiography after more than 48 hours.

New Insights Into the Use of the 12-Lead Electrocardiogram for Diagnosing Acute Myocardial Infarction in the Emergency Department

The 12-lead electrocardiogram (ECG) remains the most immediately accessible and widely used initial diagnostic tool for guiding management in patients with suspected myocardial infarction (MI). Although the development of high-sensitivity cardiac troponin assays has improved the rule-in and rule-out and risk stratification of acute MI without ST elevation, the immediate management of the subset of acute MI with acute coronary occlusion depends on integrating clinical presentation and ECG findings. Careful interpretation of the ECG might yield subtle features suggestive of ischemia that might facilitate more rapid triage of patients with subtle acute coronary occlusion or, conversely, in identification of ST-elevation MI mimics (pseudo ST-elevation MI patterns). Our goal in this review article is to consider recent advances in the use of the ECG to diagnose coronary occlusion MIs, including the application of rules that allow MI to be diagnosed on the basis of atypical ECG manifestations. Such rules include the modified Sgarbossa criteria allowing identification of acute MI in left bundle branch block or ventricular pacing, the 3- and 4-variable formula to differentiate normal ST elevation (formerly called early repolarization) from subtle ECG signs of left anterior descending coronary artery occlusion, the differentiation of ST elevation of left ventricular aneurysm from that of acute anterior MI, and the use of lead aVL in the recognition of inferior MI. Improved use of the ECG is essential to improving the diagnosis and appropriate early management of acute coronary occlusion MIs, which will lead to improved outcomes for patients who present with acute coronary syndrome.

Left Circumflex Coronary Artery as the Culprit Vessel in ST-Segment-Elevation Myocardial Infarction

The prevalence of the left circumflex coronary artery (LCx) as the culprit vessel in ST-segment-elevation myocardial infarction (STEMI) is reportedly lowest among that of the 3 main epicardial arteries, and has not been described for non-STEMI (NSTEMI) and stable angina pectoris. We sought to define the distribution of culprit arteries in these clinical presentations and suggest mechanisms for the differences. We reviewed 189 coronary angiograms of patients with STEMI, 203 with NSTEMI, and 548 with stable angina (n=940), and compared distributions of stenotic and culprit coronary arteries (lesions prompting intervention). Obstructive coronary lesions (≥50% narrowing) were more prevalent in the left anterior descending coronary artery (LAD) (36%-38%) and similar in the LCx and right coronary artery (RCA) (27%-29%), regardless of clinical presentation (P <0.01). In NSTEMI and stable angina, culprit vessels and total obstructive disease had the same distribution. In STEMI, however, a culprit LCx was significantly less prevalent (17%) than was total obstructive disease (27%; P <0.01), or a culprit LAD (47%) or RCA (34%) (both P <0.001). In our computed tomographic angiographic model of coronary longitudinal strain (percentage of shortening), LCx strain was only 1.5% ± 2.4%, versus 9.5% ± 2.9% for LAD strain and 10.1% ± 3.9% for RCA strain. In STEMI, LCx plaques seem less prone to rupturing. Culprit and total disease distributions are similar in NSTEMI and angina, suggesting a different ischemic pathophysiology in these presentations. Lower LCx longitudinal strain might contribute to reduced plaque rupture in STEMI.

A new 4-variable formula to differentiate normal variant ST segment elevation in V2-V4 (early repolarization) from subtle left anterior descending coronary occlusion - Adding QRS amplitude of V2 improves the model

INTRODUCTION

Precordial normal variant ST elevation (NV-STE), previously often called "early repolarization," may be difficult to differentiate from subtle ischemic STE due to left anterior descending (LAD) occlusion. We previously derived and validated a logistic regression formula that was far superior to STE alone for differentiating the two entities on the ECG. The tool uses R-wave amplitude in lead V4 (RAV4), ST elevation at 60 ms after the J-point in lead V3 (STE60V3) and the computerized Bazett-corrected QT interval (QTc-B). The 3-variable formula is: 1.196 x STE60V3 + 0.059 × QTc-B - 0.326 × RAV4 with a value ≥23.4 likely to be acute myocardial infarction (AMI).

HYPOTHESIS

Adding QRS voltage in V2 (QRSV2) would improve the accuracy of the formula.

METHODS

355 consecutive cases of proven LAD occlusion were reviewed, and those that were obvious ST elevation myocardial infarction were excluded. Exclusion was based on one straight or convex ST segment in V2-V6, 1 millimeter of summed inferior ST depression, any anterior ST depression, Q-waves, "terminal QRS distortion," or any ST elevation >5 mm. The NV-STE group comprised emergency department patients with chest pain who ruled out for AMI by serial troponins, had a cardiologist ECG read of "NV-STE," and had at least 1 mm of STE in V2 and V3. R-wave amplitude in lead V4 (RAV4), ST elevation at 60 ms after the J-point in lead V3 (STE60V3) and the computerized Bazett-corrected QT interval (QTc-B) had previously been measured in all ECGs; physicians blinded to outcome then measured QRSV2 in all ECGs. A 4-variable formula was derived to more accurately classify LAD occlusion vs. NV-STE and optimize area under the curve (AUC) and compared with the previous 3-variable formula.

RESULTS

There were 143 subtle LAD occlusions and 171 NV-STE. A low QRSV2 added diagnostic utility. The derived 4-variable formula is: 0.052*QTc-B - 0.151*QRSV2 - 0.268*RV4 + 1.062*STE60V3. The 3-variable formula had an AUC of 0.9538 vs. 0.9686 for the 4-variable formula (p = 0.0092). At the same specificity as the 3-variable formula [90.6%, at which cutpoint (≥23.4), 123 of 143 MI were correctly classified for 86% sensitivity], the sensitivity of the new formula at cutpoint ≥17.75 is 90.2%, with 129/143 correctly classified MI, identifying an additional 6 cases. The cutpoint with the highest accuracy (92.0%) was at a cutoff value ≥18.2, with 88.8% sensitivity, 94.7% specificity, and a positive and negative likelihood ratio of 16.9 (95% CI: 8.9-32) and 0.12 (95% CI: 0.07-0.19). At this cutpoint, it correctly classified an additional 11 cases (289 of 315, vs. 278 of 315): 127/143 for MI (an additional 4 cases) and 162/171 for NV-STE (an additional 7 cases).

CONCLUSION

On the ECG, a 4-variable formula was derived which adds QRSV2; it differentiates subtle LAD occlusion from NV-STE better than the 3-variable formula. At a value ≥18.2, the formula (0.052*QTc-B - 0.151*QRSV2 - 0.268*RV4 + 1.062*STE60V3) was very accurate, sensitive, and specific, with excellent positive and negative likelihood ratios. This formula needs to be validated.

Validation of the modified Sgarbossa criteria for acute coronary occlusion in the setting of left bundle branch block: A retrospective case-control study

BACKGROUND

The modified Sgarbossa criteria were proposed in a derivation study to be superior to the original criteria for diagnosing acute coronary occlusion (ACO) in left bundle branch block (LBBB). The new rule replaces the third criterion (5 mm of excessively discordant ST elevation [STE]) with a proportion (at least 1 mm STE and STE/S wave ≤-0.25). We sought to validate the modified criteria.

METHODS

This retrospective case-control study was performed by chart review in 2 tertiary care center emergency departments (EDs) and 1 regional referral center. A billing database was used at 1 site to identify all ED patients with LBBB and ischemic symptoms between May 2009 and June 2012. In addition, all 3 sites identified LBBB ACO patients who underwent emergent catheterization. We measured QRS amplitude and J-point deviation in all leads, blinded to outcomes. Acute coronary occlusion was determined by angiographic findings and cardiac biomarker levels, which were collected blinded to electrocardiograms. Diagnostic statistics of each rule were calculated and compared using McNemar's test.

RESULTS

Our consecutive cohort search identified 258 patients: 9 had ACO, and 249 were controls. Among the 3 sites, an additional 36 cases of ACO were identified, for a total of 45 ACO cases and 249 controls. The modified criteria were significantly more sensitive than the original weighted criteria (80% vs 49%, P < .001) and unweighted criteria (80% vs 56%, P < .001). Specificity of the modified criteria was not statistically different from the original weighted criteria (99% vs 100%, P = .5) but was significantly greater than the original unweighted criteria (99% vs 94%, P = .004).

CONCLUSIONS

The modified Sgarbossa criteria were superior to the original criteria for identifying ACO in LBBB.

Significant narrowing of the circumflex artery leads to worse outcomes than right coronary artery narrowing in patients with anterior myocardial infarction treated invasively

BACKGROUND

Occlusion of the circumflex artery (Cx) often does not present signs in the ECG. It can lead to delayed angiography during ST-elevation myocardial infarction (STEMI). The aim of this analysis was to determine if Cx narrowing is related to diverse outcomes in comparison with right coronary artery (RCA) stenosis in patients with STEMI, treated with percutaneous coronary intervention (PCI) of the left descending artery (LAD).

METHODS AND RESULTS

Inclusion criteria were as follows: first STEMI treated with PCI of the LAD and additional significant (≥ 70 %) Cx or RCA narrowing-two-vessel disease. A total of 234 consecutive patients with STEMI were included. Total mortality was estimated during long-term follow-up, at mean 639 (± 224) days after STEMI. Patients with Cx narrowing constituted 46 % (N = 108) of the study population, and patients with RCA narrowing amounted to 54 % (N = 126). Patients with narrowing of the Cx had worse long-term outcomes in terms of mortality than patients with RCA narrowing (22 vs. 11 %, p < 0.05, respectively). Multiple regression analysis showed independent risk factors for death during long-term follow-up such as: age, ejection fraction and Cx narrowing.

CONCLUSION

Significant Cx narrowing leads to worse outcomes than RCA narrowing in patients with STEMI treated with PCI of the LAD.

Incidence, angiographic features and outcomes of patients presenting with subtle ST-elevation myocardial infarction

BACKGROUND

Borderline electrocardiograms represent a challenge in ST-segment elevation myocardial infarction (STEMI) management and are associated with inappropriate discharges and delays to intervention.

OBJECTIVES

To assess angiographic characteristics and outcomes of patients presenting with subtle ST-elevation (STE) myocardial infarction.

METHODS

A total of 504 consecutive patients with suspected STEMI treated by systematic primary percutaneous coronary intervention were prospectively included. Subtle STE was defined as a maximal preinterventional STE of 0.1 to 1 mm. Angiograms were interpreted by investigators unaware of the electrocardiographic data.

RESULTS

The proportion of patients with subtle STE was 18.3%, 86% of them presented with Thrombolysis In Myocardial Infarction flow grade 0/1 and 91% underwent percutaneous coronary intervention. Despite having smaller infarcts, subtle STE patients associated more frequent multivessel disease (57% vs 44%, P = .02) and larger delays to reperfusion. During a follow-up of 19.0 ± 4.9 months, the rates of death or reinfarction were similar among groups (10.0% vs 12.6%, P = .467). Subtle STE was not associated with better outcomes neither in univariate nor after adjustment in a multivariate analysis (adjusted hazard ratio 0.79, 95% CI 0.37-1.69, P = .546).

CONCLUSIONS

Subtle STEMI is frequent in clinical practice and is usually associated with acute total coronary occlusion. Therefore, it should be diagnosed and treated in the same expeditiously manner as marked STEMI.

Predictive value of electrocardiogram in diagnosing acute coronary artery lesions among patients with out-of-hospital-cardiac-arrest

AIMS

Acute coronary lesions are known to be the most common trigger of out of hospital cardiac arrest (OHCA). Aim of the present study was to assess the predictive value of ST-segment changes in diagnosing the presence of acute coronary lesions among OHCA patients

METHODS

Findings of coronary angiography (CA) performed in patients resuscitated from OCHA were retrospectively reviewed and related to ST-segment changes on post-ROSC electrocardiogram (ECG) RESULTS: Ninety-one patients underwent CA after OHCA; 44% of patients had ST-segment elevation and 56% of patients had other ECG patterns on post-ROSC ECG. Significant coronary artery disease (CAD) was found in 86% of patients; CAD was observed in 98% of patients with ST-segment elevation and in 77% of patients with other ECG patterns on post-ROSC ECG (p=0.004). Acute or presumed recent coronary artery lesions were diagnosed in 56% of patients, respectively in 85% of patients with ST-segment elevation and in 33% of patients with other ECG patterns (p<0.001). ST-segment analysis on post-ROSC ECG has a good positive predictive value but a low negative predictive value in diagnosing the presence of acute or presumed recent coronary artery lesions (85% and 67%, respectively)

CONCLUSIONS

Electrocardiographic findings after OHCA should not be considered as strict selection criteria for performing emergent CA in patients resuscitated from OHCA without obvious extra-cardiac cause; even in the absence of ST-segment elevation on post-ROSC ECG, acute culprit coronary lesions may be present and considered the trigger of cardiac arrest.