Early diagnosis of right ventricular or posterior infarction associated with inferior wall left ventricular acute myocardial infarction

Right ventricular infarction: epidemiological, clinical, and angiographic characteristics and the outcomes through the experience of a Moroccan cardiology department

Background

Acute myocardial infarction (MI) is a major cause of cardiovascular mortality, which is the leading cause of death in the world. Our objective in this study was to evaluate the epidemiological, clinical, and angiographic features of right ventricular infarction (RVI), as well as its complications and its therapeutic approaches.

Patients and methods

It is a single-centered retrospective descriptive study conducted over a period of 2 years from November 2018 to October 2020. The authors included 82 patients with RVI hospitalized in the cardiovascular ICU during the initial phase of acute coronary syndrome with persistent ST segment elevation. Patients who were diagnosed with RVI at electrocardiogram and echocardiography were recruited.

Results

The authors included 500 patients hospitalized for STEMI, 82 had MI extended to the RV, reflecting a rate of 16.4%. The mean age in our study was 64±12.3 years. Dyslipidemia, diabetes mellitus, and hypertension were the most common cardiovascular risk factors among these patients. RVI co-existed with inferior MI in 62.2 of cases and in 37.8% of anterior MI, while isolated RVI was seen in only one patient. Transthoracic echocardiography showed right ventricular (RV) systolic dysfunction in 24.39% of cases, while RV dilatation was seen in only 10.9% of patients. Therapeutic approach was based essentially on revascularization with thrombolysis and coronary angiography +/- PCI. The percentage of mortality was 2.4%.

Conclusion

RVI is relatively rare and is mostly related to an extension of an inferior MI. Early diagnosis, prompt treatment, and appropriate are the keys to improve prognosis, and reduce complications.

The Role of Doppler Imaging in the Assessment of Right Ventricular Function: a Case-control Study of Acute Inferior Wall Infarction

Background

Right ventricular infarction (RVI) develops in 30-50% of patients with inferior wall infarction (IWI). The rates of mortality, morbidity, and complications in these patients are greater than in the patients without RVI. We compared the tissue Doppler imaging (TDI) indices between a group of patients with IWI and RVI, with a similar group of patients who had IWI alone to investigate the application of TDI indices in the evaluation and detection of right ventricular function.

Material and Methods

We studied 49 patients with first acute IWI in two groups. Group 1 (N=24) were patients with IWI and RVI while group 2 consisted of patients with IWI alone (N=25), based on standard electrocardiogram criteria. The peak systolic (Sm), peak early (Em) and late (Am) diastolic velocities, and Em/Am ratio were obtained from the apical four chamber view, at the lateral side of the tricuspid annulus. We measured trans-tricuspid early (ET) and peak (AT) filling velocity, ET/AT ratio, right ventricular end diastolic diameter (RVEDD), and tricuspid annular plane systolic excursion (TAPSE) by M-mode TDI projected at the long axis of parasternal view.

Results

The RVEDD and E/Em ratio were increased, while the TAPSE was significantly decreased in the patients with RVI as compared to those without RVI (4.7± 0.6 vs. 3.1±0.2 cm; p < 0.005, 5.6±2.21 Vs 4.5±1.2; p<0.006 and 1.7±0.4 vs. 2.3±0.5 cm; p <0.0001, respectively). However, the other statistically measured parameters were not significantly different between these groups.

Conclusion

The measurement of RVEDD, E/Em ratio, and TAPSE, as right ventricular myocardial systolic and diastolic parameters by pulse wave TDI could be used to objectively assess the status of RV condition in patients with first acute IWI.

Usefulness of right ventricular tissue Doppler imaging for diagnosis of right ventricular myocardial infarction

BACKGROUND

Right ventricular myocardial infarction (RVMI) is a complication of acute inferior myocardial infarction and sometimes causes severe hemodynamic disturbance. It is therefore important to promptly detect RVMI and assess the severity of right ventricular (RV) dysfunction. Tissue Doppler imaging (TDI) is a useful method to assess left ventricular function and RV function. In this study, we investigated the possibility of diagnosing RVMI using tricuspid annular velocity determined by TDI.

METHODS

Thirty consecutive patients with first acute inferior myocardial infarction were studied. The diagnosis of RVMI was based on an ST-segment elevation of at least 0.1 mV in lead V4R. The patients were classified into 12 patients with RVMI (the RVMI group) and 18 patients without RVMI (non-RVMI group). All patients underwent two-dimensional echocardiography, pulsed Doppler and TDI, and coronary angiography within 48 h after onset of myocardial infarction. Tricuspid inflow velocity was recorded by pulsed Doppler and early diastolic tricuspid inflow velocity (TVE) was measured. Peak early diastolic velocity of the tricuspid annulus (TVe') at the RV free wall was recorded using TDI. The ratio of TVE to TVe' (TVE/TVe') was calculated.

RESULTS

TVe' was significantly lower in the RVMI group compared to that in the non-RVMI group (5.9 ± 1.3 vs. 9.1 ± 3.1; p = 0.0025). On the basis of a TVe' cutoff value of less than 8.3 cm/s, RVMI was diagnosed with 100 % sensitivity and 61 % specificity.

CONCLUSIONS

The early diastolic tricuspid annular velocity determined by TDI is a noninvasive and sensitive index for diagnosing RVMI.

A study of the clinical profile of right ventricular infarction in context to inferior wall myocardial infarction in a tertiary care centre

INTRODUCTION

Right ventricular infarction, previously thought to be rare and recently thought to be common, is commonly associated with inferior wall myocardial infarction. We will hereby study the clinical profile of right ventricular infarction (as diagnosed by right precordial electrocardiography) in patients with acute inferior wall myocardial infarction and the clinical course of RV infarction in inferior wall myocardial infarction in terms of complications.

AIMS AND OBJECTIVES

1. To study the incidence of right ventricular infarction in patients of acute inferior myocardial infarction using right precordial electrocardiography. 2. To study the complications of right ventricular infarction. 3. To study the response of specific therapy in patients with right ventricular infarction.

MATERIALS & METHODS

50 patients with a history of chest pain less than 24 h were included in the study, standard 12 leads electrocardiography along with right side chest leads were taken on admission and on daily morning at 7 AM routinely for the first three days. A detailed clinical examination was done to find out the presence of right ventricular failure, left ventricular failure, hypotension and cardiogenic shock at the time of admission. Each patient was subjected to investigations viz. cardiac enzymes. Patients were grouped into two groups group A and group B according to the presence or absence of right ventricular infarction respectively.

RESULTS

Of the total studied 50 patients, 16 patients had right ventricular infarction in association with inferior wall infarction of left ventricle. Complicated course was present in 75% of patients in group A as compared to 29.42% of patients in group B.

CONCLUSION

Complications and in-hospital mortality rates were more common in patients with right ventricular infarction than in patients without it.

Comparison of an automated algorithm to expert physician interpretation of 80-lead body surface mapping in the evaluation of acute myocardial ischemia and infarction in patients presenting to the emergency department with chest pain: results from the Optimal Cardiovascular Diagnostic Evaluation Enabling Faster Treatment of Myocardial Infarction trial

INTRODUCTION/BACKGROUND

Eighty-lead (80 L) body surface map (BSM) technology provides electrocardiogram data for the clinician to interpret. A BSM device also offers an automated interpretation. Little information is available about the performance of automated algorithm interpretation in comparison to human interpretation of the 80 L BSM.

METHODS

Interpretations of BSMs by automated algorithm and a core laboratory of physician readers from The Optimal Cardiovascular Diagnostic Evaluation Enabling Faster Treatment of Myocardial Infarction trial were compared. The κ statistic and its 95% confidence interval for concordance were calculated. The effect of BSM quality on concordance was also analyzed.

RESULTS

3405 maps for 1601 subjects were reviewed by the core laboratory and automated algorithm. There was a combined concordance rate of 87.3% (κ = 0.46; 95% confidence interval, 0.40-0.52). A decrease in signal quality was associated with a decrease in concordance between human and automated algorithm interpretation (κ = 0.52 for good quality vs κ = 0.30 for poor quality).

CONCLUSION

A moderate degree of concordance was noted between physician and automated algorithm interpretation of 80 L BSMs. Signal quality of 80 L electrocardiographic BSM directly affected concordance.

Incremental benefit of 80-lead electrocardiogram body surface mapping over the 12-lead electrocardiogram in the detection of acute coronary syndromes in patients without ST-elevation myocardial infarction: Results from the Optimal Cardiovascular Diagnostic Evaluation Enabling Faster Treatment of Myocardial Infarction (OCCULT MI) trial

BACKGROUND

The initial 12-lead (12L) electrocardiogram (ECG) has low sensitivity to detect myocardial infarction (MI) and acute coronary syndromes (ACS) in the emergency department (ED). Yet, early therapies in these patients have been shown to improve outcomes.

OBJECTIVES

The Optimal Cardiovascular Diagnostic Evaluation Enabling Faster Treatment of Myocardial Infarction (OCCULT-MI) trial was a multicenter trial comparing a novel 80-lead mapping system (80L) to standard 12L ECG in patients with chest pain and presumed ACS. This secondary analysis analyzed the incremental value of the 80L over the 12L in the detection of high-risk ECG abnormalities (ST-segment elevation or ST depression) in patients with MI and ACS, after eliminating all patients diagnosed with ST-elevation MI (STEMI) by 12L ECG.

METHODS

Chest pain patients presenting to one of 12 academic EDs were diagnosed and treated according to the standard care of that site and its clinicians; the clinicians were blinded to 80L results. MI was defined by discharge diagnosis of non-ST-elevation MI (NSTEMI) or unstable angina (UA) with an elevated troponin. ACS was defined as discharge diagnosis of NSTEMI or UA with at least one positive test result (troponin, stress test, angiogram) or revascularization procedure.

RESULTS

  Of the 1,830 patients enrolled in the trial, 91 patients with physician-diagnosed STEMI and 225 patients with missing 80L or 12L data were eliminated from the analysis; no discharge diagnosis was available for one additional patient. Of the remaining 1,513 patients, 408 had ACS, 206 had MI, and one had missing status. The sensitivity of the 80L was significantly higher than that of the 12L for detecting MI (19.4% vs. 10.4%, p = 0.0014) and ACS (12.3% vs. 7.1%, p = 0.0025). Specificities remained high for both tests, but were somewhat lower for 80L than for 12L for detecting both MI and ACS. Negative and positive likelihood ratios (LR) were not statistically different between groups. In patients with severe disease (defined by stenosis > 70% at catheterization, percutaneous coronary intervention, coronary artery bypass graft, or death from any cause), the 80L had significantly higher sensitivity for detecting MI (with equivalent specificity), but not ACS.

CONCLUSIONS

Among patients without ST elevation on the 12L ECG, the 80L body surface mapping technology detects more patients with MI or ACS than the 12L, while maintaining a high degree of specificity.

Future developments in chest pain diagnosis and management

Much of the focus of research on patients with chest pain is directed at technological advances in the diagnosis and management of acute coronary syndrome (ACS), pulmonary embolism (PE), and acute aortic dissection (AAD), despite there being no significant difference at 4 years as regards mortality, ongoing chest pain, and quality of life between patients presenting to the emergency department with noncardiac chest pain and those with cardiac chest pain. This article examines future developments in the diagnosis and management of patients with suspected ACS, PE, AAD, gastrointestinal disease, and musculoskeletal chest pain.

Assessment of right ventricular diastolic function by tissue Doppler imaging in patients with acute right ventricular myocardial infarction

BACKGROUND

It is known that right ventricular systolic parameters as assessed by color tissue Doppler imaging (TDI) are abnormal in patients with inferior wall ST elevation myocardial infarction (IWMI) with right ventricular myocardial infarction (RVMI). This study was undertaken to determine right ventricular diastolic function as assessed by TDI in patients with acute RVMI.

METHODS

Thirty-five patients with first IWMI were studied and compared with 20 age-matched healthy controls, and categorized into those with (14 patients) and without (21 patients) RVMI based on standard ECG criteria. Peak systolic, peak early and late diastolic velocities (Sm, Em, and Am), Em/Am ratio along with time to Sm (ECG Q-Sm) and time to Em (ECG Q-Em) were acquired from the apical 4-chamber view at the lateral side of tricuspid annulus using TDI.

RESULTS

Sm, Em, and Em/Am ratio was reduced significantly in patients with RVMI as compared with those without RVMI and healthy individuals (Sm [11.1 + or - 2.9] vs. [14 + or - 1.9] and [14.5 + or - 2.1] cm/sec, P < 0.01; Em [9.2 + or - 3.5] vs. [12.9 + or - 3] and [14.0 + or - 2.0] cm/sec, P < 0.01; Em/Am ratio 0.53 + or - 0.2 vs. 0.78 + or - 0.19 and 0.8 + or - 0.3 [P < 0.0001]). Among the intervals, there was significant prolongation of Q-Em (558 + or - 14.8 vs. 507 + or - 16.2 and 480 + or - 20 ms [P < 0.0001]) but Q-Sm and Am were not statistically different between the groups.

CONCLUSION

Right ventricular TDI diastolic parameters are abnormal in patients with RVMI. The method of recording the velocities and time intervals are simple and can be used to assess right ventricular diastolic function in patients with RVMI. (Echocardiography 2010;27:539-543).

Body surface mapping: potential role in a chest pain critical care pathway

Recent advances in biomarkers have improved the evaluation of patients with acute chest pain, but current critical care pathways may still lead to important delays in early diagnosis and, hence, treatment of acute myocardial infarction (AMI). Electrocardiographic changes may occur within seconds of an ischemic insult, but the conventional 12-lead electrocardiogram (ECG) typically has only 50% to 60% sensitivity for diagnosis of AMI. Recording of multiple ECGs over a larger thoracic surface area, including the right ventricular, high left lateral, and posterior regions, by body surface mapping (BSM) has been made feasible in the setting of acute coronary syndromes by novel developments in electrode technology and simultaneous multichannel ECG data acquisition. Clinical studies of an Food and Drug Adminstration-approved BSM system (PRIME-ECG) have demonstrated improved early diagnosis of AMI in patients without 12-lead ST elevation and improved detection of right ventricular or posterior involvement in ST elevation MI. The improved diagnostic sensitivity compared with the conventional 12-lead ECG coupled with the potential reduction of delay to diagnosis compared with biomarkers suggest that BSM may have an important role as part of a chest pain critical care pathway for evaluation of patients with ischemic type chest pain.

Magnitude and consequences of missing the acute infarct-related circumflex artery

Emergent reperfusion strategies are integral to providing optimal patient outcomes in the setting of acute coronary artery occlusion. ST-segment elevation on the surface 12-lead electrocardiogram, although specific as a surrogate marker, is insensitive to acute posterior circulation coronary artery occlusion. Studies of non-ST-segment elevation acute coronary syndrome consistently identify patients who have epicardial vessel occlusion at the time of initial angiography, which is usually delayed for hours or days after the initial presentation. In addition, studies of ST-segment elevation myocardial infarction often divulge a disparity in identification of the infarct-related artery, with an underrepresentation of the left circumflex artery. Taken together, it is likely that many patients with left circumflex artery occlusion are "missed" during the early phases of myocardial infarction due to the electrocardiographically silent nature of the posterior territory, resulting in delayed myocardial salvage and worse cardiovascular outcomes. In this review, we report on the magnitude of missed left circumflex infarction and the consequences of this delay in diagnosis. We review the electrocardiographic findings of left circumflex occlusion and discuss strategies to enhance early identification. Heightened awareness of this clinical scenario and the available methods to avoid missing this elusive diagnosis are imperative in our quest to further improve the outcomes of patients with acute myocardial infarction.

Body surface mapping vs 12-lead electrocardiography to detect ST-elevation myocardial infarction

A prospective, multicenter trial was conducted in patients with nontraumatic chest pain in 4 hospitals to determine whether an 80-lead body surface map electrocardiogram system (80-lead BSM ECG) improves detection of ST-segment elevation in acute myocardial infarction (STEMI) compared with a standard 12-lead electrocardiogram (ECG) in an emergency department (ED) setting. A trained ED or cardiology staff member (technician or nurse) recorded a 12-lead ECG and 80-lead BSM ECG from each subject at initial presentation. Serial biomarkers (total creatine kinase [CK], CK-MB, and/or troponin) were obtained according to individual hospital practice. Of the 647 patients evaluated, 589 had available biomarkers results. Eighty-lead BSM ECG improved detection of biomarker-confirmed STEMI compared with the 12-lead ECG for CK-MB-defined STEMI (100% vs 72.7%, P = .031; n = 364) or troponin-defined STEMI (92.9% vs 60.7%, P = .022; n = 225). Specificity for STEMI was high (range, 94.9%-97.1%) with no significant difference between 80-lead BSM ECG and 12-lead ECG. Right ventricular involvement complicating inferior STEMI was detected by 80-lead BSM ECG in 2 (22%) of 9 patients with CK-MB-defined MI and in 2 (22%) of 9 patients with troponin-defined MI. The infarct location missed most commonly on 12-lead ECG but detected by 80-lead BSM ECG was inferoposterior MI. We conclude that BSM using 80-lead BSM ECG is more sensitive for detection of STEMI than 12-lead ECG, while retaining similar specificity.

Acute detection of ST-elevation myocardial infarction missed on standard 12-Lead ECG with a novel 80-lead real-time digital body surface map: primary results from the multicenter OCCULT MI trial

STUDY OBJECTIVE

Although 80-lead ECG body surface mapping is more sensitive for ST-elevation myocardial infarction (STEMI) than the 12-lead ECG, its clinical utility in chest pain in the emergency department (ED) has not been studied. We sought to determine the prevalence, clinical care patterns, and clinical outcomes of patients with STEMI identified on 80-lead but not on 12-lead (80-lead-only STEMI).

METHODS

The Optimal Cardiovascular Diagnostic Evaluation Enabling Faster Treatment of Myocardial Infarction trial was a multicenter prospective observational study of moderate- to high-risk chest pain patients presenting to the ED. Patients received simultaneous 12-lead and 80-lead ECGs as part of their initial evaluation and were treated according to the standard of care, with clinicians blinded to the 80-lead results. The primary outcome of the trial was door-to-sheath time in patients with 80-lead-only STEMI versus patients with STEMI identified by 12-lead alone (12-lead STEMI). Secondary outcomes included angiographic and clinical outcomes at 30 days.

RESULTS

One thousand eight hundred thirty patients were evaluated, 91 had a discharge diagnosis of 12-lead STEMI, and 25 patients met criteria for 80-lead-only STEMI. Eighty-four of the 91 12-lead STEMI patients underwent cardiac catheterization, with a median door-to-sheath time of 54 minutes, versus 14 of the 25 80-lead-only STEMI patients, with a door-to-sheath time of 1,002 minutes (estimated treatment difference in median=881; 95% confidence interval 181 to 1,079 minutes). Clinical outcomes and revascularization rates, however, were similar between 80-lead-only STEMI and 12-lead STEMI patients.

CONCLUSION

The 80-lead ECG provides an incremental 27.5% increase in STEMI detection versus the 12-lead. Patients with 80-lead-only STEMI have adverse outcomes similar to those of 12-lead STEMI patients but are treated with delayed or conservative invasive strategies.

Analysis of the extension of Q-waves after infarction with body surface map: Relationship with infarct size

AIMS

We aimed to characterize the extension of Q-waves after a first ST-segment elevation myocardial infarction using body surface map (BSM) and its relationship with infarct size quantified with cardiovascular magnetic resonance imaging (CMR).

METHODS AND RESULTS

Thirty-five patients were studied 6 months after a first ST-segment elevation myocardial infarction (23 anterior, 12 inferior). All cases had single-vessel disease and an open artery. The extension of Q-waves was analyzed by means of a 64-lead BSM. Infarct size was quantified with CMR. Absence of Q-waves in BSM was observed in 5 patients (14%), 2 of whom (40%) had >1 segment with transmural necrosis. Absence of Q-waves in 12-lead ECG was observed in 8 patients (23%), 7 of whom (87%) had >1 segment with transmural necrosis. Patients with inferior infarctions (n=12, 34%) showed a larger number of Q-waves in BSM (18+/-7.1 leads) than patients with anterior infarctions (n=23, 66%; 3.7+/-3.6 leads; p<0.0001). When the study group was analysed as a whole, the total number of Q-waves detected in BSM did not correlate with the number of necrotic segments (r=0.15; p=0.4). In anterior infarctions, a number of Q-waves >median (2 leads) was related to a higher number of necrotic segments (5.1+/-2.4 vs. 2+/-2.2 segments; p=0.004). The same was observed in inferior infarctions (median 20 leads: 3.5+/-1.9 vs. 1.2+/-1.2 segments; p=0.03).

CONCLUSION

In a stable phase after a first ST-segment elevation myocardial infarction, absence of Q-waves does not mean non-transmural necrosis. Using BSM, extension of Q-waves is much higher in inferior infarctions; a separate analysis depending on infarct location is necessary. A major BSM-derived extension of Q-waves is related to larger infarct size both in anterior and in inferior infarctions.

Consideration of Pitfalls in and Omissions from the Current ECG Standards for Diagnosis of Myocardial Ischemia/Infarction in Patients Who Have Acute Coronary Syndromes

The ECG is the key clinical test available for the emergency determination of which patients who presenting with acute coronary syndromes indeed have acute myocardial ischemia/infarction. Because typically the etiology is thrombosis, the correct clinical decision regarding reperfusion therapy is crucial. This review follows the efforts of an AHA working group to develop new standards for clinical application of electrocardiology. The pitfalls in the current diagnostic standards regarding ischemia/infarction that have been identified by sufficiently documented studies are corrected in their report. This article focuses on the pitfalls for which new standards will emerge in future years.

How many ECG leads do we need?

The number of leads needed in clinical electrocardiography depends on the clinical problem to be solved. The standard 12-lead ECG is so well established that alternative lead systems must prove their advantage through well-conducted clinical studies to achieve clinical acceptance. Certain additional leads seem to add valuable information in specific patient groups. The use of a large number of leads (eg, in body surface potential mapping) may add clinically relevant information, but it is cumbersome and its clinical advantage is yet to be proven. Reduced lead sets emulate the 12-lead ECG reasonably well and are especially advantageous in emergency situations.

Electrocardiographic diagnosis of non–ST-segment elevation acute coronary syndromes: current concepts for the physician

With several myocardial infarction (MI) registries reporting a decline in the incidence of ST-elevation MI (STEMI) and an increase in non-ST-elevation MI (NSTEMI) and unstable angina (UA), it is important that future healthcare resources are directed towards this increased volume of patients, ECG technology, core to the early diagnosis of these patients, has lagged behind relative to other techniques and little progress has been as far as acute coronary syndrome triage is concerned beyond ST-segment deviation. We present a review of the literature on current electrocardiographic changes which will allow admitting physicians to better risk stratify those patients with "non-diagnostic ECGs." These ECGs may become diagnostic with careful evaluation, use of serial ECGs and when additional lead sets are used.

Body surface mapping in the ED evaluation of the patient with chest pain: use of the 80-lead electrocardiogram system

Body surface mapping (BSM) is an electrocardiographic (ECG) technique that uses numerous leads on a patient's anterior and posterior chest, enabling more complete visualization of cardiac electrical activity. The rationale behind BSM is an extension of additional lead ECG. Output from BSM is displayed in a 12-lead ECG format, an 80-lead ECG format, and on color contour maps. The color contour maps can be displayed on a torso image or as a flat map.

Classification of acute coronary syndromes using the 12-lead electrocardiogram as a guide

The management of patients with acute coronary syndromes (ACS) is becoming more complicated. With the advent of new therapies and surgical techniques, the likelihood that patients will make a full recovery improves. Cardiovascular disease remains the leading cause of death for adults in the United States, and with continually increasing trends such as obesity and diabetes, will likely remain so in the future. With the introduction of improved therapies, the numbers of patients dying after their first myocardial infarction continues to decline. Electrocardiogram (ECG) technology has improved, and further research has improved its sensitivity and specificity allowing for earlier, more consistent diagnosis of ACS. As a result, guidelines have been developed to assist nurses and clinicians in the management of patients with ACS. Nurses are in a unique position to provide primary triage, recognize ACS based on the patient's presentation and initial 12-lead ECG, and initiate an appropriate response. Key elements of 12-lead ECG interpretation and their application to established guidelines are essential skills for nurses working in clinical arenas frequented by patients with ACS.

Detection of evolving right ventricular infarct during right coronary artery stent insertion using PRIME ECG body surface mapping with colour map reconstruction

We present the evolutionary changes of isolated right ventricular infarction (RVI) in a patient undergoing right coronary artery stenting using a novel imaging system. Twelve ECG and body surface maps were recorded at 30-s intervals during right coronary angioplasty, during which a right ventricular branch of the right coronary artery (RCA) occluded, resulting in a short-lived episode of chest pain and minor changes on a 12 lead ECG. Using computer-derived colour reconstruction of the ECG data, the changes of isolated right ventricular infarction is obvious, in contrast to the transient and equivocal changes seen on the 12 lead ECG.

CONCLUSION

Isolated RVI may be missed on 12 lead ECG criteria. Body surface mapping (BSM) allows unequivocal diagnosis of isolated RVI by colour map reconstruction that is able to localise the ischaemic change.

Temporal analysis of the depolarization wave of healed myocardial infarction in body surface potential mapping

BACKGROUND

We studied the ability of different time segments of the depolarization wave recorded with body surface potential mapping (BSPM) to detect and localize myocardial infarction (MI).

METHODS

BSPM was recorded in 24 patients with remote MI and in 24 healthy controls. Cine and contrast-enhanced magnetic resonance imaging (MRI) was used as a reference method. Patients were grouped according to anatomical location of their MI. The QRS complex was divided into six temporally equal segments, for which time integrals were calculated.

RESULTS

The time segments of the QRS complex showed different MI detection capability depending on MI location. For anterior infarction the second segment of the QRS complex was the best in MI detection and the optimal area was on the right inferior quadrant of the thorax (time integral average -1.5 +/- 1.8 mVms patients, 1.0 +/- 1.6 mVms controls, P = 0.002). For lateral infarction the first segment of the QRS complex performed best and the optimal area for MI detection was the left fourth intercostal area (time integral average 1.8 +/- 1.0 mVms patients, 0.7 +/- 0.5 mVms controls, P = 0.024). For inferior and posterior MI the mid-phases of the QRS complex were the best and the optimal area was the mid-inferior area of the thorax (time integral average -6.2 +/- 8.3 mVms patients, 3.3 +/- 4.3 mVms controls, P = 0.002; -9.1 +/- 6.1 mVms patients, 0.6 +/- 7.1 mVms controls, P = 0.001, respectively).

CONCLUSIONS

Time segment analysis of the depolarization wave offers potential for improving the detection and localization of healed MI.

Body surface potential mapping improves detection of ST segment alteration during percutaneous coronary intervention

BACKGROUND

The 12-lead electrocardiogram underestimates ST segment alteration in acute coronary syndromes compared with multi-lead body surface mapping. We assessed whether 80-lead mapping would improve detection of ST alteration during percutaneous coronary intervention.

METHODS

Simultaneous maps and 12-lead electrocardiograms were recorded pre-procedure, during balloon inflation and post-procedure from patients undergoing elective intervention to native coronary arteries. Recordings were obtained from 39 inflations (19 patients). All arteries were successfully stented.

RESULTS

Mean 'lead specific' ST alteration (the difference in ST elevation/depression between pre-procedure and inflation recordings in the lead showing maximal ST alteration) was greater on the map than on electrocardiogram, both for ST elevation (0.16+/-0.02 vs. 0.06+/-0.01 mV; p<0.001) and ST depression (0.11+/-0.017 vs. -0.03+/-0.006 mV; p<0.001). During first inflations (n=19), mean lead specific ST elevation and depression on map were greater than on electrocardiogram (0.20+/-0.034 vs. 0.07+/-0.015 mV; p<0.001 and 0.11+/-0.029 vs. 0.03+/-0.009 mV; p=0.001, respectively). Mapping detected greater summated ST elevation and depression during inflation than electrocardiogram (0.04+/-0.005 vs. 0.021+/-0.003 mV; p<0.001 and 0.026+/-0.004 vs. 0.011+/-0.002 mV; p<0.001, respectively). Qualitative analysis of maps and electrocardiograms showed that 21/39 (53.8%) maps recorded during inflation met criteria for myocardial ischaemia compared with 7/39 (17.9%) electrocardiograms (p<0.001).

CONCLUSION

Body surface mapping compared with the 12-lead electrocardiogram improves detection of myocardial ischaemia during intervention.

A novel method for the detection of transient myocardial ischaemia using body surface electrocardiac mapping

BACKGROUND

The limitations of the 12-lead ECG in the detection of myocardial ischaemia are well known. This study sought to test the hypothesis that a Body Surface Mapping (BSM) system can detect and localise the transient regional ischaemia induced by elective percutaneous coronary intervention (PCI) in patients with stable angina.

METHODS AND RESULTS

25 patients undergoing elective single vessel PCI were studied: 11 with RCA lesions, 9 with LAD lesions and 5 with circumflex lesions. Patients had BSM readings every 30 s following the inflation of a dilating balloon in the target vessel for 1 min. BSMs were analysed for ST segment change at 60 ms after the J point (ST60). Peak ST changes were analysed and colour map reconstruction made. Characteristic ST segment changes in each arterial domain were observed following inflation of the balloon. Maximal change occurred in a standard V lead on only 2/46 occasions. Statistically significant rapid rise and fall of ST 60 readings were observed indicating the onset recovery and location of the transient ischaemia. A novel method for the presentation of colour map reconstruction that removes baseline noise has been developed.

CONCLUSIONS

These data confirm the hypothesis that this BSM system can detect and display transient myocardial ischaemia. BSM may represent a novel clinical tool for the assessment of clinical ischaemia.

Electrocardiographic manifestations: acute inferior wall myocardial infarction

The 12-lead electrocardiogram (EKG) is an important tool in evaluating the patient with acute myocardial infarction (MI). Patients with acute inferior wall myocardial infarction (IWMI) represent a heterogeneous group in terms of morbidity, mortality, Emergency Department (ED) management, and site of occlusion in the culprit coronary artery. The standard 12-lead EKG, right-sided chest leads and posterior chest leads, in conjunction with clinical findings often provide the necessary information for the Emergency Physician (EP) to predict complications, morbidity and mortality. IWMI patients may have associated right ventricular infarction (RVI) or lateral and posterior wall extension. Each of these entities is associated with specific hemodynamic abnormalities and increased mortality. In addition, various atrioventricular (AV) blocks are commonly associated with IWMI. This article presents several cases of IWMI with EKGs and a discussion of EKG interpretation in the setting of IWMI.

12-lead ECG interpretation 2: right ventricular and posterior infarcts

Some myocardial abnormalities can have serious consequences if not detected, and may negatively affect overall patient outcomes. Right ventricular and posterior myocardial infarction are two types of myocardial injury that may seriously affect the patient's haemodynamics status, but can be recognized easily if appropriate specialized 12-lead electrocardiograms (ECGs) are recorded and analysed. The nurse is best-placed to conduct advanced ECG interpretation, in partnership with medical colleagues, and taking into account the patient's clinical symptoms and cardiac risk factors. This article should be read in conjunction with the first article (Vol 12(21): 1248-55).

The use of calculated epicardial potentials improves significantly the sensitivity of a diagnostic algorithm in the detection of acute myocardial infarction

Inverse electrocardiography can calculate epicardial potentials (EP) from body surface potentials (BSP) taking into account a thoracic volume conductor model (TVCM). Previous studies have shown that a tailored TVCM is superior to a general TVCM in calculating EP. However, construction of a tailored TVCM for a patient in an acute clinical setting is impractical. In this study we used a general TVCM in our EP calculations to determine whether this improves detection of acute myocardial infarction (AMI) using a diagnostic algorithm. BSP were derived from the 80-lead body surface map (BSM). Consecutive patients (n=379) with ischemic type chest pain were recruited. The BSM and a 12-lead electrocardiogram (ECG) were recorded at initial presentation and creatine kinase (CK) and/or CK-MB were measured initially, 12 and 24 hours postsymptom onset. A physician interpreted the 12-lead electrocardiogram and documented ST elevation if present. AMI was defined by the World Health Organization (WHO) criteria. The diagnostic algorithm result for each patient using BSP and calculated EP were documented. AMI occurred in 171 patients. The diagnostic algorithm using BSP identified 106 of these as ST elevation AMI (STEMI) (sensitivity 62%, specificity 80%). The same algorithm using EP identified 133 as STEMI (sensitivity 78%, specificity 80%). Calculated EP improved the algorithm's diagnostic sensitivity by a factor of 1.25 (P<.001) with no significant difference in specificity. Calculated EP using a general TVCM significantly improves the sensitivity of a diagnostic algorithm based on BSP in detection of AMI with no significant loss in specificity.

Additional electrocardiographic leads in the ED chest pain patient: right ventricular and posterior leads

In the evaluation of the patient with chest pain, the 12-lead electro cardiogram is a less-than-(ECG) perfect indicator of acute myocardial infarction (AMI), particularly when used early in the course of the acute ischemic event; this relative insensitivity for AMI results from many different issues, including a less-than-optimal imaging of certain areas of the heart. It has been suggested that the sensitivity of the 12-lead ECG can be improved if 3 additional body surface leads are used in selected individuals. Acute posterior (PMI) and right ventricular myocardial infarctions are likely to be underdiagnosed, because the standard lead placement of the 12-lead ECG does not allow these areas to be assessed directly. Additional leads frequently used include leads V(8) and V(9), which image the posterior wall of the left ventricle, and lead V(4R), which reflects the status of the right ventricle. The standard ECG coupled with these additional leads constitutes the 15-lead ECG, the most frequently used additional lead ECG in clinical practice. The use of the additional leads might not only confirm the presence of AMI, but also provide a more accurate reflection of the true extent of myocardial damage.

Body surface mapping improves early diagnosis of acute myocardial infarction in patients with chest pain and left bundle branch block

OBJECTIVE

To test prospectively depolarisation and repolarisation body surface maps (BSMs) for mirror image reversal, which is less susceptible to artefact, in patients with acute ischaemic-type chest pain, and to compare these BSM criteria with previously published 12 lead ECG criteria.

METHODS

An 80 lead portable BSM system was used to map patients presenting with acute ischaemic-type chest pain and a 12 lead ECG with left bundle branch block (LBBB). Acute myocardial infarction (AMI) was defined by serial cardiac enzymes. Each 12 lead ECG was assessed by the criteria of Sgarbossa et al and Hands et al for diagnosis of AMI. Depolarisation and repolarisation BSMs were assessed for loss of mirror image reversal of QRS with ST-T isointegral map patterns and a change in vector angle from QRS to ST-T outside 180+/-15 degrees -findings typically seen in LBBB with AMI.

RESULTS

Of 56 patients with chest pain and LBBB, 18 had enzymatically confirmed AMI. Patients with loss of BSM image reversal were significantly more likely to have AMI (odds ratio 4.9, 95% confidence interval 1.5 to 16.4, p = 0.007). Loss of BSM image reversal was significantly more sensitive (67%) for AMI than either 12 lead ECG method (17%, 33%) albeit with some loss in specificity (BSM 71%, 12 lead ECG 87%, 97%). Patients with AMI compared with those without AMI had a greater mean change in vector angle outside the normal range (180+/-15 degrees ), particularly between QRS isointegral and ST60 isopotential (the potential 60 ms after the J point at each electrode site) BSMs (19 degrees v 9 degrees, p = 0.038). Loss of image reversal and QRS-ST60 vector change outside 180+/-15 degrees had 61% sensitivity and 82% specificity for AMI (odds ratio 7.0, 95% confidence interval 2.0 to 24.4, p = 0.001).

CONCLUSIONS

BSM compared with the 12 lead ECG improved the early diagnosis of AMI in the presence of LBBB.

Comparison of the 80-lead body surface map to physician and to 12-lead electrocardiogram in detection of acute myocardial infarction

Diagnosis of non-ST-elevation acute myocardial infarction (AMI) by a 12-lead electrocardiogram has poor sensitivity and specificity and, therefore, relies on biochemical markers of myocardial necrosis, which can only be reliably detected within 14 to 16 hours from symptom onset. The body surface map (BSM) improves AMI detection but is limited by its interpretation by inexperienced medical staff. To facilitate interpretation, an automated BSM algorithm was developed and is evaluated in this study. One hundred three patients with ischemic-type chest pain were recruited for this study from December 2001 to April 2002. A 12-lead electrocardiogram (Marquette Mac 5K) and BSM (PRIME-ECG) were recorded at initial presentation, and cardiac troponin I and/or creatine kinase-MB levels measured at 12 hours after symptom onset. The admitting physician's 12-lead electrocardiographic (ECG) interpretation, 12-lead ECG algorithm (Marquette 12 SL V233) diagnosis, and BSM algorithm diagnosis were documented for each patient. AMI, defined by elevation of troponin I to >1 microg/L and/or creatine kinase-MB to >25U/L, occurred in 53 patients. The admitting physician diagnosed 24 patients with AMI (sensitivity 45%, specificity 94%), the 12-lead ECG algorithm diagnosed 17 patients with AMI (sensitivity 32%, specificity 98%), and the BSM algorithm diagnosed 34 patients with AMI (sensitivity 64%, specificity 94%). The BSM algorithm improved the diagnostic sensitivity by 2.0 (p <0.001) and 1.4 (p = 0.002) compared with the 12-lead ECG algorithm or the admitting physician, respectively. There was no significant difference in specificity. Thus, the BSM algorithm improves detection of AMI compared with the 12-lead ECG algorithm or physician's 12-lead ECG interpretation.

New parameters in identification of right ventricular myocardial infarction and proximal right coronary artery lesion

OBJECTIVE

The diagnosis of right ventricular myocardial infarction (RVMI) accompanied by acute inferior myocardial infarction (MI) is still a problem that we encounter. This study was designed to find out the usefulness both of peak myocardial systolic velocity (Sm) and of the myocardial performance index (MPI) of the right ventricle measured by pulsed-wave tissue Doppler imaging (TDI) in assessing right ventricular function.

METHODS

Sixty patients who experienced a first acute inferior MI (mean [+/- SD] age, 57 +/- 9 years) were prospectively assessed. An ST-segment elevation of >or= 0.1 mV in V(4)-V(6)R lead derivations was defined as an RVMI. From the echocardiographic apical four-chamber view, the Sm, the peak early diastolic velocity, peak late diastolic velocity, the ejection time, the isovolumetric relaxation time, and the contraction time of the right ventricle were recorded at the level of the tricuspid annulus by using TDI. Then, the MPI was calculated. The patients were classified into the following three groups, according to the localization of the infarct-related artery (IRA) detected using coronary angiography: group I, proximal right coronary artery; group II, distal right coronary artery; and group III, circumflex coronary artery.

RESULTS

RVMIs were detected in sixteen patients, and the IRA in 27 patients was the proximal right coronary artery. The right ventricular Sm was observed to be significantly low in patients with RVMIs and those in group I compared to those without RVMIs and those in groups II and III (10.9 +/- 1.3 vs 14.3 +/- 3.2 cm/s, respectively [p < 0.001]; 11.5 +/- 2.5 vs 15.1 +/- 3 cm/s, respectively; and 14.9 +/- 2.6 cm/s, respectively [p < 0.001]). In the diagnosis of RVMI, the values for sensitivity, specificity, negative predictive value, and positive predictive value of Sm < 12 cm/s were 81%, 82%, 92%, and 62% respectively, and in the diagnosis of the proximal right coronary artery as the IRA, those values were 63%, 88%, 74%, and 81%, respectively. The MPI was high in the same patient groups (0.83 +/- 0.12 vs 0.57 +/- 0.11 in those patients without RVMI, respectively, [p < 0.001]; 0.74 +/- 0.13 vs 0.56 +/- 0.15 in group II and 0.54 +/- 0.07 in group III, respectively [p < 0.001]). The sensitivity, specificity, negative predictive value, and positive predictive value of an MPI of > 0.70 in the diagnosis of RVMI were calculated as 94%, 80%, 97%, and 63%, respectively, and in the diagnosis of the proximal right coronary artery as the IRA, those values were 78%, 91%, 83%, and 88% respectively.

CONCLUSIONS

An Sm <12 cm/s and an MPI > 0.70 obtained by TDI may define RVMI concomitant with acute inferior MI, and the IRA.

ST-T integral and T-wave amplitude in detection of exercise-induced myocardial ischemia evaluated with body surface potential mapping

Body surface potential mapping is superior to 12-lead electrocardiogram in detection of acute and old myocardial infarctions. We examined the capability of the ST-T integral and T wave to detect exercise-induced ischemia in body surface potential mapping. Body surface potential mapping with 123 channels was recorded in 70 subjects: 45 coronary artery disease (CAD) patients and 25 healthy controls during supine bicycle exercise testing. Of the patients, 18 had anterior, 14 posterior, and 13 inferior ischemia documented by coronary angiography and thallium scintigraphy. The ST-T isointegral area, as well as the positive and negative ST-T area, and the T-wave apex amplitude were determined. Discriminant index analysis was used to find the sites that optimally separated patient subgroups from other patients and controls. In the pooled CAD group, the optimal sites for detecting the decrease in ST-T isointegral, in the positive ST-T area and in the T-wave amplitude were over the left side (ST-T isointegral area: CAD -3.8 +/- 14 microVs and controls 24 +/- 14 microVs; T-wave amplitude: CAD 3 +/- 110 microV and controls 190 +/- 90 microV; P <.001, both). The area under the receiver operating characteristic curve for the decrease in ST-T isointegral, in the positive ST-T area, and in the T-wave amplitude and for the ST depression were 94%, 95%, 92%, and 93%, respectively. T wave performed especially well in patients with multivessel disease. In stepwise logistic regression analysis, using the presence of CAD as the dependent parameter, the decrease in the positive ST-T area and ST depression were the only parameters that entered the model. ST-T area and T-wave amplitude are sensitive and specific markers of transient myocardial ischemia. ST-T area contains information additional to ST depression and has thus independent discriminative value in ischemia detection.

Beyond the 12 lead: review of the use of additional leads for the early electrocardiographic diagnosis of acute myocardial infarction

Despite known limitations, the standard 12 lead ECG is the principal risk stratification device for patients presenting with chest pain to the ED. However, it has a sensitivity of less than 60% for MI. One reason for this is that the standard placement of chest leads fails to interrogate many areas of the myocardium. Various workers have addressed this problem through the use of additional leads or body surface mapping. Additional leads on the posterior and right thoracic surface have been shown to give additional information, which may be important to the emergency physician. This review demonstrates the need for additional leads in the acute setting and makes recommendations about the utility of using additional leads in the ED.

ST-segment level and slope in exercise-induced myocardial ischemia evaluated with body surface potential mapping

Body surface potential mapping (BSPM) is superior to 12-lead electrocardiography for detection of acute and old myocardial infarctions (MIs). We used BSPM to examine electrocardiographic criteria for acute reversible myocardial ischemia. BSPM with 123 channels was performed in 45 patients with coronary artery disease (CAD) and 25 healthy controls during supine bicycle exercise testing. Of the 45 patients, 18 patients had anterior, 14 had posterior, and 13 had inferior ischemia documented by coronary angiography and thallium scintigraphy. The ST amplitude was measured 60 ms after the J-point and the ST slope calculated by fitting a regression line from the J-point to 60 ms after it. The optimal locations for detecting ST depression and ST-slope decrease were identified. In the pooled CAD patient group, the optimal location for ST depression was 5 cm below standard lead V(5) (CAD group: -70 +/- 70 microV; controls: 70 +/- 80 microV, p <0.001). Using a cut-off value of -10 microV, the ST depression separated the patients with CAD from controls with a sensitivity of 84% and a specificity of 96%. The ST slope became more horizontal in the patient group than in the control group. The optimal location for ST-slope decrease was over the left side (CAD group: 20 +/- 20 microV/s; controls: 720 +/- 320 microV/s, p <0.001). Using a cut-off value of 320 microV/s, the ST slope separated patients with CAD from controls with a sensitivity of 93% at a specificity level of 88%. The area under the receiver operating characteristic curve of ST slope tended to be higher than the one of ST depression (97% vs 93%; p = 0.097). In conclusion, regions sensitive for ST depression and for ST-slope decrease could be identified in BSPM, despite variation in the location of ischemia and the presence or absence of a history of MI. ST slope is a sensitive and specific marker of transient myocardial ischemia, and might perform even better than ST depression.

Electrocardiographic manifestations: Acute posterior wall myocardial infarction

Posterior myocardial infarction (PMI) refers to infarction of the posterior wall of the left ventricle. Although often associated with inferior and lateral myocardial infarctions, detection of acute PMI is difficult because the standard 12-lead electrocardiogram does not adequately image the posterior wall of the left ventricle. We review the findings on 12-lead electrocardiogram with PMI, as well as discuss the utility of additional electrocardiographic leads in the diagnosis of PMI.