Ratio of ST-segment depression in lead V2 to ST-segment elevation in lead aVF in evolving inferior acute myocardial infarction: an aid to the early recognition of right ventricular ischemia

ECG-based techniques to enhance clinical practice in cardiac genetic disease management

INTRODUCTION

Inherited cardiomyopathies are associated with a broad spectrum of potentially lethal phenotypes characterized by structural and electrical myocardial remodeling. Increased awareness and genetic cascade screening lead to more genotype-positive, yet phenotype-negative individuals to be evaluated and followed up. The predictive value of genetic testing is hampered by incomplete penetrance and high variability in disease onset, progression and severity.

CLINICAL CHALLENGES

Dilated cardiomyopathy usually manifests with symptoms of heart failure and ventricular arrhythmias (VA) develop in advanced disease. In arrhythmogenic cardiomyopathy (ACM), electrical remodeling can precede structural and functional changes and life-threatening VA can be the first disease manifestation. Early signs and symptoms may be subtle and go unnoticed. Physicians are in great need of appropriate screening and risk-stratification strategies. Task Force Criteria (TFC) were established to standardize the clinical diagnosis of ACM but risk-stratification remains challenging. Accurate prediction of disease progression in variation carriers is currently beyond the capabilities of diagnostic tests.

PROPOSED DIAGNOSTIC TECHNIQUES

We propose three ECG-based techniques; isopotential mapping, inverse ECG and CineECG, to enhance risk-stratification in ACM. With the use of isopotential mapping abnormal spatio-temporal activation and repolarization may be identified. Furthermore, by combining subject specific ≥12‑lead ECG data with cardiothoracic imaging using inverse ECG techniques, the direct link between ECG and cardiac anatomy can be obtained.

CONCLUSION

New ECG techniques may prove more sensitive to detect early de- and repolarization abnormalities in yet asymptomatic variation carriers. Early electrical signs of disease progression may be identified prior to symptoms. Furthermore, individualized risk-stratification may be enhanced.

Right ventricular infarction--diagnosis and treatment

Right ventricular infarction (RVI) as assessed by various diagnostic methods accompanies inferior-posterior wall myocardial infarction (MI) in 30 to 50% of patients. Recognition of the syndrome of RVI is important as it defines a significant clinical entity, which is associated with considerable immediate morbidity and mortality and has a well-delineated set of priorities for its management. Patients may clinically present with hypotension, elevated jugular venous pulse (JVP), and occasionally shock, all in the presence of clear lung fields. The ST-segment elevation of > or = 0.1 mV in the right precordial leads V4R is a readily available electrocardiographic sign used for diagnosis of RVI. Other diagnostic approaches for assessing RVI include echocardiography, radionuclide ventriculography, technetium pyrophosphate scanning, and hemodynamic measurements. The proper management of RVI includes volume loading to maintain adequate right ventricular preload, ionotropic support, and maintenance of atrioventricular synchrony. Reperfusion therapy should be initiated at the earliest signs of right ventricular dysfunction. Finally, complete recovery over a period of weeks to months is a rule in a majority of patients, suggesting right ventricular "stunning" rather than irreversible necrosis has occurred.

The utility of the standard 12-lead electrocardiogram in the prediction of proximal right coronary artery occlusion in acute inferior myocardial infarction

Prior studies have proposed several electrocardiogram criteria for identifying patients with acute inferior ST-segment elevation myocardial infarction (iSTEMI) caused by obstruction of the proximal part of the right coronary artery (RCA). We applied 11 of these criteria and three new ones to the admission electrocardiograms of 80 patients admitted with an acute iSTEMI in order to evaluate their utility. All patients received thrombolytic treatment and underwent coronary angiography during the hospitalization. Four previously described criteria (ST-segment depression in lead V1, ST-segment depression in leads V1-V3, maximum ST-segment depression in the precordial leads, and ST-segment depression in lead V3 of <or= 50% of the magnitude of ST-segment elevation in lead III) and two new used criteria (the absence of ST-segment depression in lead V1 in combination with ST-segment depression in lead V2 and the arithmetic sum of the ST-segment: III + V3 > 1) were useful in identifying patients with obstruction of the proximal part of the RCA. Among the six criteria, ST depression in V1-V3 had the highest specificity (77.2%) and positive predictive value (56.5%), and a new criterion-the arithmetic sum of the ST-elevation in V3/ST-elevation in III < 0.5--had the highest sensitivity (80.9%) and negative predictive value (86.7%). Six criteria were helpful in identifying patients with acute iSTEMI caused by obstruction of the proximal part of the RCA. One of these has not been previously reported and has the higher specificity and negative predictive value.

Assessment of right ventricular infarction with contrast-enhanced magnetic resonance imaging

OBJECTIVE

Evaluation of contrast-enhanced magnetic resonance imaging to assess right ventricular infarction in patients with acute inferior myocardial infarction.

BACKGROUND

Contrast-enhanced magnetic resonance imaging has been used for assessing scar tissue after left ventricular infarction. The value of contrast-enhanced magnetic resonance imaging to assess right ventricular infarction is unknown and was evaluated.

METHODS

Consecutive patients (n=18) with first acute inferior infarction were included. Resting electrocardiogram and right-sided electrocardiogram were acquired to assess right ventricular involvement. Resting cine magnetic resonance imaging was performed to evaluate right ventricular function and volumes, whereas the extent of right ventricular scar tissue was assessed by contrast-enhanced magnetic resonance imaging. Cine magnetic resonance imaging was repeated at 6-months follow-up to re-assess right ventricular function and volumes.

RESULTS

Sensitivity and specificity of magnetic resonance imaging were 100 and 78%, respectively, to detect right ventricular infarction (using the right-sided electrocardiogram as the gold standard). At 6 months follow-up, patients with scar tissue on contrast-enhanced magnetic resonance imaging showed right ventricular dilatation. Moreover, the extent of right ventricular scar tissue was linearly related to the severity of right ventricular dilatation.

CONCLUSIONS

Contrast-enhanced magnetic resonance imaging permits accurate assessment of right ventricular scar tissue. Patients with extensive right ventricular infarction demonstrate right ventricular dilatation at 6 months follow-up.

The diagnostic value of 12-lead electrocardiogram in predicting infarct-related artery and right ventricular involvement in acute inferior myocardial infarction

BACKGROUND

The aim of the present study was to investigate the predictive value of presentation and 24-hour electrocardiograms in defining the infarct-related artery (IRA), its lesion segment, and the right ventricular involvement in acute inferior myocardial infarction (MI).

METHODS

One hundred forty-nine patients with acute inferior MI were included. Infarct-related artery, its lesion segment, and the validity of new ECG criteria for the diagnosis of right ventricular MI (RVMI) were investigated by means of criteria obtained from admission and 24- hour ECGs.

RESULTS

The presence of ST-segment elevation in lead III > lead II criterion (Criterion 1) and ST-segment depression in lead I > lead aVL criterion (Criterion 2) from admission ECG defined the right coronary artery (RCA) as IRA with a sensitivity of 64% and a specificity of 100%. These two criteria also defined the proximal or mid lesions in RCA as culprit lesions (sensitivity of 99%, specificity of 96%). Absence of these two criteria indicated Cx as IRA with a sensitivity of 50% and a specificity of 97%. The depth of Q wave in lead III > lead II criterion (Criterion 3) had no value for discrimination of IRA, but the width of Q wave in lead III > lead II criterion (Criterion 4) supported the RCA to be IRA with a sensitivity of 60% and a specificity of 61% (Criteria 3 and 4 were obtained from 24-hour ECGs). The finding of Criterion 1 plus Criterion 5 (ST elevation in V(1) but no ST elevation in V2) on admission ECG had a sensitivity of 63% and a specificity of 99% in the diagnosis of RVMI.

CONCLUSION

We concluded that 12-lead ECG is a cheap, easy, and readily obtainable diagnostic approach in discrimination of IRA and its culprit lesion segment. However, despite high specificity, due to moderate degree sensitivity, its value for the diagnosis of RVMI is questionable.

ST-segment depression in lead aVR: a useful predictor of impaired myocardial reperfusion in patients with inferior acute myocardial infarction

STUDY OBJECTIVE

During inferior acute myocardial infarction (AMI), the ECG lead aVR is frequently ignored, and therefore its clinical significance remains unclear. We examined the relation between ST-segment deviation seen in lead aVR on ECGs obtained at hospital admission and myocardial reperfusion in patients who have experienced recanalized inferior AMIs.

DESIGN AND SETTING

Retrospective study.

PATIENTS

A total of 225 patients with inferior AMIs in whom Thrombolysis in Myocardial Infarction grade 3 flow was achieved within 6 h after symptom onset.

MEASUREMENTS AND RESULTS

Patients were classified as follows according to ST-segment deviation in lead aVR on an ECG obtained at hospital admission: group A, 103 patients with no ST-segment depression; group B, 80 patients with ST-segment depression of < or = 1.0 mm; and group C, 42 patients with ST-segment depression of > 1.0 mm. There were no differences in time from symptom onset to hospital admission or in the culprit lesion among the three groups. The degree of ST-segment elevation in leads II, III, aVF, V5, or V6, the degree of ST-segment depression in leads V1 to V4, and the sum of ST-segment deviation in these leads were lowest in group A and highest in group C. In groups A, B, and C, the incidence of impaired myocardial reperfusion, defined as myocardial blush grade 0/1, was 2%, 23%, and 67%, respectively (p < 0.001). The sensitivity and negative predictive values of ST-segment depression in lead aVR for impaired myocardial reperfusion were higher than those based on other ECG variables. Multivariate analysis showed that the degree of ST-segment depression in lead aVR was an independent predictor of impaired myocardial reperfusion (odds ratio 8.41; 95% confidence interval, 2.96 to 23.9; p < 0.001).

CONCLUSIONS

We conclude that the degree of ST-segment depression in lead aVR is a useful predictor of impaired myocardial reperfusion in patients who have experienced inferior AMIs.

Diagnostic value of aVL derivation for right ventricular involvement in patients with acute inferior myocardial infarction

BACKGROUND

Right ventricular (RV) involvement is associated with increased morbidity and mortality in patients with acute inferior myocardial infarction (MI). Although electrocardiography is probably the most useful, simple, and objective tool for the diagnosis of acute MI, there are no well-defined criteria in the standard 12-lead electrocardiogram to properly identify RV involvement in patients with acute inferior MI. Our objective was to evaluate the value of ST-segment depression in lead aVL in diagnosing RV involvement in patients with acute inferior MI.

MATERIALS AND METHODS

Sixty-seven patients, hospitalized with acute inferior myocardial infarction, were included in this study. The diagnosis of acute inferior myocardial infarction was based on the clinical history, characteristic enzyme pattern of CK-MB values, and the appearance of ST-segment elevation > or = 1 mm in at least two of the leads (leads II, III, aVF). RV infarction was defined by ST-segment elevation > or = 1mm in lead V4R. ST-segment depression in lead aVL that is more than 1 mm was accepted as a diagnostic criterion for RV involvement in patients with acute inferior MI.

RESULTS

Thirty-one patients had >1 mm ST-segment depression and 28 of them had right ventricular infarction according to lead V4R. Thirty-six patients showed < or =1 mm ST-segment depression indicating no right ventricular involvement but four of them also had right ventricular infarction according to V4R.

CONCLUSION

More than 1 mm ST-segment depression in lead aVL was found to have high sensitivity (87%), specificity (91%), high positive and negative predictive value (90%, 88%, respectively), and high diagnostic accuracy (89%) in diagnosing RV involvement in patients with acute inferior MI. Therefore, by using a simple 12-lead electrocardiographic sign, ST-segment depression >1 mm in lead aVL, obtained on admission, it is possible to identify RV involvement in patients with acute inferior MI.

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.

Electrocardiographic algorithm for assignment of occluded vessel in acute myocardial infarction

BACKGROUND

This study was performed to elaborate an electrocardiographic (ECG) algorithm enabling assignment of an occluded coronary artery in acute myocardial infarction (AMI).

PATIENTS AND INTERVENTIONS

In 109 patients (age, 59+/-12 years) with AMI (pain onset, 3.6+/-1.7 h), coronary angiography with PTCA/stenting of the culprit lesion was performed. The diagnosis of AMI was confirmed by emergency coronary angiography and laboratory analyses. Admission ECG parameters (amplitude of R-wave, ST-segment deviation, presence of Q-wave, deflection of T-wave) in standard 12-lead ECG plus extended (V(3)R to V(6)R and V(7-9)) leads were subjected to classification and regression tree (CART) analysis.

RESULTS

Continuous CART analysis assessed ST-segment deviations in V(2) and V(5)R. AMI of the left anterior descending (LAD), right coronary artery (RCA) and left circumflex coronary artery (CX) were correctly classified in 94, 64, and 91% of cases, respectively. Dichotomised CART analysis assessed ST-segment deviations in V(2), V(5)R, and aVF. True classification rates for LAD, RCA, and CX amounted to 84, 74, and 71%, respectively.

CONCLUSIONS

Dichotomised CART analysis is a simple means of differentiation of CX from RCA occlusion during AMI.

ECG discrimination between right and left circumflex coronary arterial occlusion in patients with acute inferior myocardial infarction: value of old criteria and use of lead aVR

STUDY OBJECTIVES

Prior studies have proposed several ECG criteria for identifying the culprit artery in patients with acute inferior myocardial infarction (MI). We applied each criterion to our patients to assess its utility. In doing so, we discovered a previously unreported, but highly useful, criterion utilizing lead aVR.

STUDY DESIGN

Retrospective review.

PATIENTS

Thirty consecutive patients with symptoms of acute MI, ST-segment elevation in the inferior ECG leads, an appropriate rise and fall of creatine kinase and troponin I levels, and coronary arteriography within 7 days of the onset of symptoms.

MEASUREMENTS

The ECG recorded within 24 h of the onset of symptoms that had the most prominent ST-segment changes was analyzed. In the 12 standard leads and in lead V(4)R, ST-segment elevation or depression was measured 0.06 s after the J point.

RESULTS

Four previously described criteria were useful in identifying the right coronary artery (RCA) or the left circumflex coronary artery (LCX) as the culprit: ST-segment elevation in lead I, ST-segment more or less elevated in lead II than in lead III, ST-segment elevation >or= 0.5 mm in lead V(4)R, and various combinations of ST-segment elevation or depression in leads V(1) and V(2). A new criterion was found to be at least as useful as any previously described: the presence and amount of ST-segment depression in lead aVR.

CONCLUSIONS

At least five different ST-segment criteria help to identify the RCA or the LCX as the culprit artery in patients with acute inferior MI. One of these, the amount of ST-segment depression in lead aVR, has not been reported previously and needs validation in a larger study.

Diagnosis of acute myocardial infarction in angiographically documented occluded infarct vessel : limitations of ST-segment elevation in standard and extended ECG leads

STUDY OBJECTIVES

The majority of thrombolysis studies require defined ST-segment elevations as an inclusion criterion for the diagnosis of acute myocardial infarction (AMI). However, depending on the occluded infarct vessel and the criteria applied, the ECG diagnosis of AMI can be difficult to establish. Accordingly, this study was performed to evaluate the sensitivity of ST-segment elevation of standard and extended ECG leads in a cohort of patients with angiographically confirmed diagnosis of AMI.

PATIENTS AND METHODS

In 418 patients (mean +/- SD age, 60 +/- 13 years) with AMI (pain onset, 4.8 +/- 3.0 h), coronary angiography with percutaneous transluminal coronary angioplasty/stenting of the culprit lesion was performed. The diagnosis of AMI was confirmed by emergency coronary angiography and laboratory analyses. ST-segment elevation (in two contiguous leads) of 1 mm in standard lead I through aVF and ST-segment elevations of 2 mm (or 1 mm, corresponding values presented in parentheses) in V(1) through V(6) were considered significant. In a subset of 102 AMI patients, additional right precordial leads V(3)R through V(6)R for evaluation of right ventricular infarction and additional chest leads V(7) through V(9) for evaluation of posterior infarction were recorded. ST-segment elevations of 1 mm in the right precordial leads and 1 mm or 0.5 mm in the posterior leads were considered significant.

RESULTS

Standard leads I through V(6) showed ST-segment elevation in 85% (96%) of patients with left anterior descending artery occlusion, in 46% (61%) of patients with left circumflex coronary artery (CX) occlusion, and in 85% (90%) of patients with right coronary artery occlusion. On consideration of additional ECG tracings in the subgroup of 102 patients (V(3)R through V(6)R and V(7) through V(9)), the respective numbers increased by 2 to 8% depending on different criteria for ST-segment elevation; in patients with CX occlusion, the increase amounted to 6 to 14%. There was a trend toward an extended infarct size (maximum creatine kinase [CK] values) with concomitant ST-segment elevation in additional ECG leads as assessed by maximum CK levels.

CONCLUSIONS

The sensitivity of the ECG diagnosis of AMI is only marginally increased by extended precordial chest leads. There is a trend toward an extended infarct size in those patients with concomitant ST-segment elevation in additional ECG leads.

Value of ST elevation in lead III greater than lead II in inferior wall acute myocardial infarction for predicting in-hospital mortality and diagnosing right ventricular infarction

ST elevation in lead III > II has a higher sensitivity than lead V4R in diagnosing right ventricular myocardial infarction. Lead III > II is also predictive of in-hospital mortality.

New electrocardiographic criteria for predicting the site of coronary artery occlusion in inferior wall acute myocardial infarction

In patients with inferior wall acute myocardial infarction (AMI), the site of the culprit lesion is an important determinant of outcome. Patients with right ventricular infarction have a poor prognosis, whereas those with occlusion of the left circumflex coronary artery (LCx) have a good prognosis. Therefore, we assessed whether standard 12-lead electrocardiograms obtained on admission could identify the site of coronary artery occlusion, (i.e., a site proximal to the origin of the right ventricular branch of the right coronary artery [RCA], a site distal to the origin of the right ventricular branch of the RCA, or a site in the LCx). The ratio of ST depression in lead V3 to ST elevation in lead III (V3/III ratio) was evaluated immediately before coronary angiography in 152 patients with a first inferior wall AMI confirmed by coronary angiography within 12 hours after the onset of symptoms. For occlusion of the proximal RCA, distal RCA, and LCx, V3/III ratio was 0.2+/-0.3, 0.8+/-0.5, and 2.5+/-2.5 (p = 0.0001), respectively. The V3/III ratio <0.5 identified proximal RCA occlusion, 0.5 <V3/III ratio < or = 1.2 identified distal RCA occlusion, and 1.2 <V3/III ratio identified LCx occlusion with sensitivities of 91%, 84%, and 84%, and specificities of 91%, 93%, and 95%, respectively. We conclude that the V3/III ratio is useful in predicting the site of coronary artery occlusion in patients with inferior wall AMI.

ST-segment elevation in right precordial leads implies depressed right ventricular function after acute inferior myocardial infarction

BACKGROUND

The prognosis of acute inferior myocardial infarction is worse when it is complicated by right ventricular infarction. ST elevation in the right precordial leads is one of the reliable methods for detecting acute right ventricular infarction. The purpose of the study was to examine the relation between ST elevation in the right precordial electrocardiographic leads during acute inferior infarction and the severity of right ventricular systolic dysfunction.

METHODS

This study analyzed the relation between ST elevation > or = 0.1 mV in V4R and the severity of right ventricular systolic dysfunction in 43 consecutive patients (men/women: 35/8; average age 62+/-9 years) with acute inferior myocardial infarction with a rapid-response Swan-Ganz catheter to measure the right ventricular ejection fraction (RVEF).

RESULTS

RVEF was significantly lower in patients with ST elevation (n = 18) than in those without (n = 25) (33%+/-6% vs 40%+/-9%, p = 0.010). If the infarct-related lesion was located in the proximal right coronary artery, RVEF tended to be lower than if the lesion was located in the distal right coronary artery or the left circumflex coronary artery (33%+/-10% vs 37%+/-9% vs 42%+/-9%, p = 0.101). Logistic regression analysis demonstrated that ST elevation in V4R was the only independent predictor of depressed RVEF (odds ratio = 5.31, 95% confidence interval = 1.28 to 22.1, p = 0.022).

CONCLUSION

ST elevation in lead V4R during acute inferior myocardial infarction predicts right ventricular systolic dysfunction.

Impact of early accelerated dose tissue plasminogen activator on in-hospital patency of the infarcted vessel in patients with acute right ventricular infarction

OBJECTIVE

To assess the efficacy of early accelerated dose tissue plasminogen activator on in-hospital patency of the infarct related artery in patients with inferior myocardial infarction with and without right ventricular involvement.

DESIGN

Single centre prospective assessment before discharge of infarct related vessel patency after early thrombolysis.

SETTING

Tertiary cardiac referral centre at a university hospital.

PATIENTS AND METHODS

90 consecutive unselected patients with acute myocardial infarction, of whom 35 (39%) had electro-cardiographic evidence of right ventricular involvement (ST segment elevation greater than 0.1 mV in right precordial lead V4R), were studied. All patients received accelerated dose tissue plasminogen activator 100 mg within six hours from the onset of symptoms and had control angiography before discharge.

MAIN OUTCOME MEASURES

Infarct related coronary artery patency using the Thrombolysis in Myocardial Infarction (TIMI) grading system before discharge. Incidence of prolonged systemic hypotension, sinus bradycardia, complete atrioventricular block, and ventricular tachyarrhythmia during early hospitalisation.

RESULTS

Despite aspirin and bolus heparinisation before thrombolysis and high dose heparinisation thereafter for at least 48 hours the infarct related artery was more likely to be occluded (TIMI 0 or 1 flow) in patients with right ventricular involvement than in those without (69 v 29%, P < 0.001), as shown by control angiography performed a mean of 12.8 days after thrombolysis. These findings may be explained, at least in part, by predominant involvement of the proximal right coronary artery (66 v 31%, P < 0.05) and a low cardiac output syndrome, being indirectly reflected by a high incidence of prolonged hypotension (26 v 7%, P = 0.02), bradycardia (34 v 14%, P = 0.03), and complete atrioventricular block (37 v 5%, P = 0.0001).

CONCLUSION

Primary angioplasty should be considered as the treatment of choice in patients with acute inferior infarction with right ventricular involvement because of the high failure rate of thrombolysis.

Standard 12-lead ECG versus special chest leads in the diagnosis of right ventricular myocardial infarction

The case of a 60-year-old woman with an acute inferior transmural myocardial infarction associated with a right ventricular myocardial infarction provided an opportunity to compare the performance of the 12-lead electrocardiogram (ECG) and the right chest leads in the diagnosis of infarction of the right ventricle. While the right chest leads revealed unequivocal evidence of ischemic injury emanating from the right ventricle, the standard leads II and III showed changes compatible with inferior myocardial infarction; familiarity with vectorial interpretive concepts of ST segment deviations could provide a hint of an associated right ventricular involvement. This report is presented at a time of renewed controversy regarding the necessity of special ECG leads in the diagnosis of acute right ventricular infarction in the routine emergency department environment.

Electrocardiographic diagnosis of infarction of the right ventricular anterior wall

Fifty cases of acute myocardial infarction manifesting in anterior chest leads were studied. The site of infarction was determined by detailed two-dimensional echocardiography. Isolated left ventricular anteroseptal infarction was found in 32 patients, infarction of the anterior wall of the left as well as the right ventricle in 12, and infarction localized to the right ventricular anterior wall in 6. ST-segment depression followed by deep symmetrical T wave inversion, increasing in depth from lead V1 to lead V3 without loss of the R wave in these leads, was highly sensitive and specific in detecting isolated right ventricular anterior wall infarction. ST-segment elevation in right-sided chest leads was not useful. Concomitant ST-segment depression in inferior leads was highly specific and sensitive in diagnosing infarction of the right ventricular anterior wall in the presence of left ventricular anterior infarction.

Diagnostic value of the arithmetic sum of the ST segment of inferior and V2 leads, II + V2, III + V2 and aVF + V2 in identifying the artery responsible for inferior acute myocardial infarction

In order to evaluate electrocardiographic changes in the diagnosis of the artery responsible for inferior myocardial infarction, a prospective study was performed on inferior and V2 ST segment deviation and its correlation using the arithmetic sum: II + V2, III + V2, and aVF + V2. A group of 66 patients with inferior acute myocardial infarction (AMI) was studied. A standard 12-leads electrocardiogram was performed within six hours of the onset of chest pain. Coronary arteriography was performed on each of the patients between one and twelve weeks after infarction. Right coronary artery (RCA) lesion was found in 46 patients, 27 at a proximal level and 19 at a distal level; in 20 patients the left circumflex coronary artery was affected. The isolated value of the magnitude of the inferior ST segment is not an efficient parameter for identifying the artery responsible for inferior AMI. In lead V2 all the patients with a lesion of the left circumflex artery showed ST segment depression > or = 1 mm (P < 0.001) and all those presenting ST segment elevation had stenosis of the proximal RCA. The most useful parameters for identifying the artery responsible for inferior AMI, with 100% specificity are: (1) for occlusion of the RCA, the arithmetic sum of ST segments: aVF + V2 > 0, with 86.9% sensitivity (P < 0.001); (2) for occlusion of the left circumflex artery III + V2 < 0, with 90% sensitivity (P < 0.001); and (3) for proximal occlusion of the RCA: aVF + V2 > or = 1, with 96.2% sensitivity (P < 0.001). No specific marker was observed for distal occlusion of the RCA. The value of the arithmetic sum of the ST segment: III + V2 between 0 and 0.9 was the most significant, with 94.7% sensitivity and 95.7% specificity (P < 0.001).

Hemodynamic criteria for diagnosis of right ventricular ischemia associated with inferior wall left ventricular acute myocardial infarction

To test the diagnostic value of different hemodynamic indexes for the diagnosis of acute right ventricular (RV) ischemic dysfunction, we studied 2 groups of consecutive patients admitted for an acute left ventricular inferior wall myocardial infarction: 51 patients with (group 1) and 32 patients without (group 2) RV ischemia as determined by coronary angiography. In both groups, we analyzed by right-sided cardiac catheterization right-sided heart pressures, pulmonary capillary wedge pressure, and cardiac index. We also calculated pressure ratios (mean right atrial pressure or RV end-diastolic over pulmonary capillary wedge pressures), pulmonary vascular resistance, and RV stroke work index. We found significant differences (p < 0.01) between the 2 groups when comparing mean right atrial pressure, RV end-diastolic pressure, ratio of these 2 pressures over pulmonary capillary wedge pressure, RV stroke work index, and right atrial and RV pressure waveforms. The best combined sensitivity, specificity, positive predictive value, negative predictive value, and diagnostic accuracy were found for the right atrial M or W waveform pattern, isolated or combined with a disproportionate elevation of RV end-diastolic over pulmonary capillary wedge pressures (respectively, 92%, 94%, 90%, 87%, and 89%). Volume loading was performed in 27 patients (18 with and 9 without RV ischemia). Right heart pressures and RV stroke work index increased significantly and similarly in both groups. Cardiac index increased significantly only in patients without RV ischemia (p = 0.02). However, volume loading did not significantly modify the diagnostic value of the different hemodynamic criteria studied.(ABSTRACT TRUNCATED AT 250 WORDS)

Comparison of diagnostic accuracy, time dependency, and prognostic impact of abnormal Q waves, combined electrocardiographic criteria, and ST segment abnormalities in right ventricular infarction

OBJECTIVE

To determine the diagnostic and prognostic impact of abnormal Q waves in comparison to or in combination with ST segment abnormalities in the right precordial and inferior leads as indicators of right ventricular infarction during the acute phase of inferior myocardial infarction.

DESIGN

Prospective study of a consecutive series of 200 patients with acute inferior myocardial infarction with and without right ventricular infarction.

SETTING

Department of internal medicine, university clinic.

RESULTS

Right ventricular infarction was diagnosed in 106 (57%) out of 187 patients from the results of coronary angiography, technetium pyrophosphate scanning, and measurement of haemodynamic variables or at necropsy, or both. In the acute phase of inferior infarction ST segment elevation > or = 0.1 mV in any of the right precordial leads V4-6R was the most reliable criterion for right ventricular infarction (sensitivity, 89%; specificity, 83%). Abnormal Q waves in the right precordial leads, the most specific criterion (91%) for right ventricular infarction, were superior to ST segment elevation in patients admitted > 12 hours after the onset of symptoms. Both ST segment elevation in leads V4-6R (increase in in hospital mortality, 6.2-times; P < 0.001; major complications, 2.3-times; P < 0.01) and abnormal Q waves (2.3-times, P < 0.05; 1.8-times, P < 0.05) on admission were highly predictive of a worse outcome during the in hospital period. In the presence of inferior myocardial infarction previously proposed combined electrocardiographic criteria were not better diagnostically or prognostically than ST segment abnormalities and abnormal Q waves alone.

CONCLUSIONS

During the first 24 hours of inferior myocardial infarction ST segment elevation and abnormal Q waves derived from the right precordial leads are complementary rather than competitive criteria for reliably diagnosing right ventricular infarction, both indicating a worse in hospital course for the patient. In this they are better than any other previously proposed combined electrocardiographic criteria in diagnosing right ventricular infarction. Right precordial leads should be routinely monitored in acute inferior myocardial infarction.

Simultaneous ST-segment elevation in lead V1 and depression in lead V2. A discordant ECG pattern indicating right ventricular infarction

The major electrocardiographic change in right ventricular infarction (RVI) is ST-segment elevation in leads V4R-V6R. The authors describe a discordant electrocardiographic pattern of ST-segment elevation in lead V1 and ST-segment depression in lead V2 in five patients presenting with acute transmural (Q wave) inferior infarction and RVI. There were 51 patients with transmural inferior infarction from a thrombolytic trial. In 25 patients, the ST-segment in the right-sided precordial leads was elevated by > or = 1 mm indicating the presence of RVI. In 5 of these 25 patients, simultaneous ST-segment elevation of 1.0-8.0 mm (mean, 2.8 +/- 2.9 mm) in lead V1 and ST-segment depression of 2.5 to 4.0 mm (mean, 3.3 +/- 0.6 mm) in lead V2 were also present. The discordant pattern of the ST-segments in leads V1 and V2 is an important and specific sign for RVI.

Right ventricular infarction

Right ventricular infarction complicates up to half of inferior left ventricular infarctions. The term represents a spectrum of disease from mild, asymptomatic right ventricular dysfunction to cardiogenic shock, and it includes transient ischemic myocardial dysfunction as well as myocardial necrosis. Right ventricular infarction is associated with considerable morbidity and mortality, and its presence defines a high-risk subgroup of patients with inferior left ventricular infarction. Diagnosis of this condition requires a high degree of suspicion based on clinical findings and the early recording of the electrocardiogram through right precordial leads, as well as elevated right-sided filling pressures out of proportion to left-sided filling pressures. The proper management of right ventricular infarction requires sustaining adequate right ventricular preload with volume loading and maintenance of atrioventricular synchrony, reduction of right ventricular afterload (particularly when left ventricular dysfunction is present), and inotropic support of the right ventricle. Early reperfusion with fibrinolytic therapy or direct angioplasty is also warranted. Survivors of right ventricular infarction generally have a restoration of normal right ventricular function with resolution of hemodynamic abnormalities.

The electrocardiographic diagnosis of acute myocardial infarction in the thrombolytic era

The 12-lead ECG remains a simple and inexpensive technique to diagnose AMI in its early phases. The diagnostic accuracy of the ECG depends upon the extent of myocardial necrosis and its localization. The ECG is most sensitive in patients with occlusion of the LAD artery, followed by the RCA and the left CFA. In 10% to 20% of patients with AMI the initial ECG either shows nonspecific changes or is normal. The correlation between the ECG and infarct-related artery varies according to the involved vessel. Classic ECG changes are seen in 90% of the LAD artery, in 70% to 80% of RCA, and in only 50% of CFA occlusions. A second important issue is the mechanism and clinical significance of reciprocal ST segment changes, which usually indicate larger MI, more impaired ventricular function, worse prognosis, and in some patients, significant disease of a noninfarct-related artery. Furthermore, the value of the ECG in estimating myocardial injury and infarct size remains controversial. The ECG plays an important role in coronary reperfusion. ST segment elevation is one of the principal criteria for instituting thrombolytic therapy, and helps predict those who will most likely benefit from coronary reperfusion. The role of the ECG in evaluating the reperfusion status after coronary thrombolysis is not clear. Rapid return to baseline or normalization of the ST segment suggests opening of the occluded vessel, though a small or negligible change does not exclude successful reperfusion.

Atrial natriuretic factor in patients with right ventricular infarction

To determine the possible role of atrial natriuretic factor in right ventricular infarction, serial measurements of this hormone were performed in 21 patients with acute inferior myocardial infarction. All patients underwent enzymatic, electrocardiographic, echocardiographic and coronary arteriographic studies. Ten patients also had right heart hemodynamic measurements. Eight patients had evidence of an associated right ventricular infarction (Group I) and 13 patients did not (Group II). Enzymatically estimated infarct size, presence of left heart failure and arrhythmias were similar in both groups. Mean arterial pressure in Group I (72.1 +/- 4.4 mm Hg) was significantly lower (p = 0.02) than in Group II (89.5 +/- 4.6 mm Hg). Seven (88%) of the eight patients in Group I had elevated right atrial pressures and a higher incidence than Group II of prolonged hypotension (75%) and right ventricular dysfunction (75%) clinically and by echocardiography. Plasma atrial natriuretic factor levels (mean values +/- SEM in pg/ml) for days 1, 2, 3 and 7 after infarction were, respectively: 152 +/- 30, 165 +/- 48, 199 +/- 27 and 189 +/- 31 for Group I versus 55 +/- 9, 55 +/- 11, 61 +/- 13 and 77 +/- 20 for Group II. The difference between groups was significant for days 1 (p less than 0.05), 3 and 7 (p less than 0.01) and not significant for day 2 (p = 0.07). These findings show that atrial natriuretic factor elevation is part of the neurohumoral response to right ventricular infarction and are consistent with the hypothesis that atrial natriuretic factor may play a pathophysiologic role in the right ventricular infarct syndrome.

Electrocardiographic manifestations of right ventricular infarction

RVI is a frequent occurrence in the setting of an acute inferoposterior myocardial infarction and its early recognition has important therapeutic and prognostic implications. Because of this, diverse invasive and noninvasive diagnostic techniques have been investigated to identify patients with RVI. Electrocardiography is the most available, simple, and objective of these techniques. Numerous ECG signs of RVI have been described and some of them, especially ST segment elevation and patterns of necrosis (QS, QR) in the right precordial leads (V3R to V5R), have a very high sensitivity, specificity, and positive predictive value for the detection of RVI. ST segment elevation in lead V4R is also helpful in identifying the occluded coronary artery in patients with acute myocardial infarction, which could have great importance in their management. Hence, a 12-lead ECG with the right precordial leads (V3R to V6R) should be a routine part of the initial evaluation of patients with clinical suspicion of acute inferior myocardial infarction. This article reviews the value, limitations, and pathogenesis of the ECG manifestations of RVI.

Right ventricular infarction: diagnostic value of ST elevation in lead III exceeding that of lead II during inferior/posterior infarction and comparison with right-chest leads V3R to V7R

The diagnostic accuracy of ST elevation in lead III exceeding that of lead II (ratio III/II greater than 1) in the diagnosis of right ventricular infarction was investigated in 24 autopsied patients with inferior/posterior myocardial infarction on ECG. The results were compared with the diagnostic accuracy of ST elevation greater than or equal to 1 mm in right-chest leads V3R to V7R recorded in the same patients. All had left ventricular infarction documented at autopsy, and 17 (71%) had concomitant right ventricular involvement. The highest specificity (100%) and positive predictive value (100%) were calculated for the right-chest leads, whereas values for ratio III/II greater than 1 were 88% and 91%, respectively. The differences were not statistically significant. It is concluded that differences in ST elevation in leads III and II can be the basis for a diagnosis of right ventricular involvement in ECG-diagnosed inferior/posterior infarction. The diagnosis, however, may be achieved more easily with right-chest leads.