Influence of left ventricular cavity dimension on electrocardiographic estimation of the extent of wall motion abnormalities

To estimate the influence of left ventricular cavity dimension on the electrocardiographic estimation of the extent of wall motion abnormalities, two-dimensional echocardiograms and standard 12-lead electrocardiograms (ECG) were carried out on 221 patients within 3 months after acute myocardial infarction (MI). Among the patients with anterior MI (96 patients; 43.4%) both the extent of asynergy (% of asynergic segments, an echo index taking into account the type of asynergy) and the electrocardiographic signs of necrosis (number of Q waves greater than or equal to 40 ms, Wagner's score) were significantly greater (p less than 0.001) in those with left ventricular dilatation (60 patients) than in those with normal ventricular size (36 patients); within the latter group, the ECG-asynergy correlations were good (r value 0.67-0.79). In patients with left ventricular dilatation no correlation was found. In inferior MI (108 patients, 48.9%), asynergy was more extensive in patients with left ventricular dilatation (p less than 0.001) than in those with normal left ventricle. However, the electrocardiographic extent of necrosis was similar in the two groups and no significant ECG-asynergy correlation was found. Likewise, in anteroinferior MI (17 patients; 7.7%), the ECG-asynergy correlations were statistically insignificant in both groups. In conclusion, the electrocardiographic patterns of necrosis are poorly related to the extent of asynergy and are greatly influenced by left ventricular dimensions.     

Inaccuracy of various proposed electrocardiographic criteria in the diagnosis of apical myocardial infarction--a critical review

The diagnostic accuracy of the standard electrocardiogram (ECG) in apical myocardial infarction (MI) was evaluated in 112 consecutive patients with recent MI and wall-motion abnormalities limited to the left ventricular (LV) apex on two-dimensional echocardiography, performed at rest 21 to 84 days after MI. The following patterns of abnormal (greater than or equal to 30 ms) Q waves were found: anteroseptal (Q V1-V4) in 44 patients (39.3%), anterolateral (Q V1-V6 and/or I, aVL) in 22 (19.6%), inferior (Q III, aVF or II, III, aVF) in five (4.5%), lateral (Q I, aVL and/or V5-V6) in five (4.5%), anteroinferior in six (5.3%); non-Q MI was present in 30 patients (26.8%). By applying various proposed ECG criteria, the presence of apical MI was correctly identified in very few (24, 21%) patients. LV apex was extensively asynergic in 85 patients (76%) and partially asynergic in 27 (24%). All the patients with Q waves in lateral leads and 47% of the patients with non-Q MI had partially asynergic LV apex, while in the other ECG patterns, extensively asynergic LV apex was predominant. The presence of both greater than or equal to 30 ms Q waves and loss of R in left precordial leads and I strongly suggests extensive apical asynergy; normal QRS in the same leads, however, does not exclude extensive apical involvement.(ABSTRACT TRUNCATED AT 250 WORDS)     

心电图对冠状动脉病变的定位及预测分析

本文分析了６２例Ｑ波性心肌梗塞（ＭＩ）患者的心电图（ＥＣＧ）与病变冠状动脉及运动异常室壁的关系。结果显示，３３例前壁ＭＩ中，９４％有前降支病变，８２％有左室前壁或心尖部运动异常；３０例下壁ＭＩ中，９０％有右冠状动脉或回旋支病变（右冠状动脉占８９％），７６％有左室下壁运动异常；１０例侧壁ＭＩ中，９０％有前降支病变，７０％有左室前壁或心尖部运动异常。４８例患者可确定梗塞相关动脉，其中前壁ＭＩ对前降支病变定位诊断的预测值为８９％，下壁ＭＩ对右冠状动脉或回旋支病变定位诊断的预测值为７３％。结果表明，ＥＣＧ对Ｑ波性ＭＩ患者病变冠状动脉及运动异常室壁的定位诊断有较高的价值。     

Left ventricular asynergy in electrocardiographic "posterior" myocardial infarction

P2 300 selected patients, scalar electrocardiograms and contemporaneous radionuclide angiograms were analyzed retrospectively to assess the association between prominent right precordial R waves (duration greater than or equal to 0.04 second, R greater than or equal to S in lead V1 or V2), traditionally considered diagnostic of "posterior" infarction, and asynergy in various left ventricular segments. Mathematical methods for analysis of association between nonparametric variables clearly demonstrated that prominent right precordial R waves were strongly associated with asynergy of the basal lateral left ventricular wall, although asynergy of adjacent inferior and lateral segments was common. With the exclusion of right ventricular hypertrophy and bundle branch block, a prominent R wave in lead V1 exhibited a high specificity (greater than to 99%), a high positive predictive value (91%) and a low sensitivity (36%) for diagnosing basal lateral myocardial infarction. A prominent R wave in lead V2 exhibited a higher sensitivity (61%), a somewhat lower specificity (95%) and a significantly lower positive predictive value (76%). A newly developed criterion for such infarction--a prominent R wave in lead V2 and a Q wave inferior infarction--had intermediate characteristics and may be more clinically useful. The most common reasons for the decreased sensitivities of all three criteria were left ventricular hypertrophy or associated anterior myocardial infarction. These data demonstrate that prominent right precordial R waves are clinically useful in identifying inferior and lateral wall infarctions that involve the basal lateral left ventricular segment. Confusion results primarily from inappropriate use of the electrocardiographic term "posterior" for such infarctions.     

Q waves and ventricular asynergy: Predictive value and hemodynamic significance of anatomic localization

Two hundred sixteen consecutive patients were evaluated to determine the value of pathologic Q waves in predicting the presence and severity of ventricular asynergy. Of 64 patients with pathologic Q waves, 95 percent demonstrated asynergy. Q waves in the anterior leads denoted asynergy in 30 of 30 patients, anterior asynergy in 29 of 30 and an anterior aneurysm in 25. Q waves in the inferior leads indicated asynergy in 30 of 33 patients, inferior asynergy in 25 of 30 and an associated aneurysm in 19. Conversely, of 52 patients with an aneurysm, 44 also had pathologic Q waves. If Q waves were present, 72 percent of asynergic zones exhibited akinesis or dyskinesis; however, in the absence of Q waves an aneurysm was present in only 22 percent (P < 0.001). Hemodynamically, anterior asynergy, whether defined by Q waves or by ventriculography, was associated with more left ventricular dysfunction than was inferior asynergy (P < 0.01). Of 21 patients with a cardiomyopathy, none had pathologic Q waves.The data indicate that pathologic Q waves can aid significantly in predicting the presence and location of a severely asynergic zone. Although their absence does not exclude the possibility of asynergy, the latter is much less likely and, if present, may be of milder form.     

Q-wave prediction of myocardial infarct location, size and transmural extent at magnetic resonance imaging

OBJECTIVE: We investigated how pathologic Q waves or equivalents predict location, size and transmural extent of myocardial infarction (MI). METHODS: MI characteristics, detected by contrast-enhanced magnetic resonance imaging, were compared with 12-lead electrocardiogram in 79 patients with previous first MI. RESULTS: Q waves involved only the anterior leads (V1-V4) in 13 patients: in all patients MI involved the anterior and anteroseptal walls and apex; 81% of scar tissue was within these regions. Q waves involved only the inferior leads (II, III, aVF) in 13 patients: in 12 of these patients MI involved the inferior and inferoseptal walls; however, only 59% of scar occupied these regions. Q waves involved only lateral leads (V5, V6, I, aVL) in 11 patients: in nine of these patients MI involved the lateral wall but only 27% of scar tissue was within this wall. Q waves involved two electrocardiogram locations in 42 patients. In the 79 patients as a whole, the number of anterior Q waves was related to anterior MI size (r=0.70); however, the number of inferior and lateral Q waves was only weakly related to MI size in corresponding territories (r=0.35 and 0.33). A tall and broad R wave in V1-V2 was a more powerful predictor of lateral MI size than Q waves. Finally, the number of Q waves accurately reflected the transmural extent of the infarction (r=0.70) only in anterior infarctions. CONCLUSION: Q waves reliably predict MI location, size and transmural extent only in patients with anterior infarction. A tall and broad R wave in V1-V2 reflects a lateral MI.     

Insensitivity of the electrocardiogram in apical myocardial infarction

The ability of the standard ECG to identify myocardial infarction (MI) involving primarily the left ventricular (LV) apex is controversial. Therefore, the ECGs of 62 consecutive patients with acute infarction and isolated akinesia or dyskinesia of the LV apex on gated blood pool scintigraphy performed at rest 9 +/- 4 days after MI, were reviewed. The following distribution of Q waves was found: none, 26%; inferior leads only, 23%; anterior leads only, 32%; inferior + 1 or more V leads, 13%; lead I and/or aVL + 1 or more V leads, 6%. Only 12 patients (19%) demonstrated one of the "combination" Q-wave patterns thought to indicate apical infarction. Although the 20 patients with a history of MI did not differ in age or ejection fraction from those with a first MI, the combination of inferior and anterior Q waves was present in 6 of them (30%), vs only 2 of the remaining 42 patients (5%) (p less than 0.02). The 24 patients with apical dyskinesia had a lower ejection fraction (36 +/- 14 vs 48 +/- 12, p less than 0.001), a lower prevalence of isolated inferior Q waves (8 vs 32%, p less than 0.05) and a greater prevalence of isolated anterior Q waves (46 vs 24%, p = 0.09) than those with akinesia. Thus, in patients with recent MI localized to the LV apex on radionuclide ventriculography, pathologic Q waves are commonly confined to the anterior or inferior leads or absent altogether. The insensitivity of the various proposed criteria for the electrocardiographic diagnosis of apical MI emphasizes the value of imaging techniques in detecting this common clinical entity.     

Right bundle-branch block in coronary artery disease: a hemodynamic and angiographic study

Thirty-four patients with right bundle-branch block (RBBB) and coronary artery disease (CAD) (RBBB was not pre-existent to clinical development of CAD) and 52 consecutive CAD patients without conduction disturbances were studied and compared to verify whether the presence of RBBB implies more severe and extensive left ventricular myocardial damage as well as more severe CAD. The two groups did not differ either in age or in New York Heart Association functional class. The incidence or location of previous myocardial infarction (MI) was not different in the two groups. No significant differences were found in left ventricular volumes or ejection fraction. Higher end-diastolic left ventricular pressure and more severe and diffuse left ventricular wall asynergy were present in RBBB patients. At coronary arteriography, more severe involvement of the right coronary artery in CAD patients without conduction disturbances was the only significant finding. The group of patients with CAD and RBBB without MI showed significantly less involvement of the left anterior descending coronary artery and significantly more severe damage of the inferior wall of the left ventricle than the group with CAD without RBBB and MI. Patients with inferior wall MI and RBBB had more severe asynergy of the posterobasal region of the left ventricle than did patients with inferior wall MI without RBBB. The group of patients with anterior wall MI and RBBB had a higher left ventricular end-diastolic pressure, a lower left ventricular ejection fraction, and a greater extent of myocardial damage compared to similar patients of the control group. The groups with MI and RBBB had the same Gensini's score as similar groups without RBBB. (ABSTRACT TRUNCATED AT 250 WORDS)     

Diagnostic value of electrocardiogram and vectorcardiogram in postinfarction ventricular asynergy

The ability of ECG-VCG to predict the severity of postinfarction LV asynergy was evaluated in 152 patients with previous myocardial infarction who underwent left cineventriculography in the right anterior oblique view. Various ECG and VCG signs were examined in order to predict the existence of severe asynergy in general (dyskinesia or akinesia or severe hypokinesia) and of dyskinesia in particular. In patients with inferior myocardial infarction (Group A) persistent ST segment elevation was the only specific ECG sign (100%) of severe asynergy; it had a poor sensitivity (6.2%). Four frontal VCG signs (presence of terminal bite, y- greater than 0.18 mV, maximum early superior vector along x axis = MESV greater than or equal to 1.3 mV, duration of initial superior forces = DISF greater than 50 msec) increased the sensitivity of the ECG-VCG method to 75.8% while maintaining a 100% specificity. Regarding the diagnosis of dyskinesia, only the ECG sign of persistent ST segment elevation and the VCG sign of y- greater than or equal to 0.3 mV had a 100% specificity. The sensitivity of the ECG-VCG method was 33.3% (16.6% ECG and 16.6% VCG). In patients with anterior myocardial infarction (Group B), concerning the diagnosis of severe asynergy, the ECG signs of sigma ST greater than 3 mm in anterior leads; pathologic Q wave in four or more anterior leads (including D1 and aVL); and the presence of LAH or LAH + RBBB, had a 100% specificity and a good sensitivity (60.5%). The VCG sign of a narrow horizontal QRS loop increased the sensitivity of the ECG-VCG method to 71% while maintaining a 100% specificity. As for the diagnosis of dyskinesia, the ECG signs with a 100% specificity were sigma ST greater than or equal to 5 mm in anterior leads, a pathologic Q wave in more than five anterior leads (including I and a VL) and RBBB + LAH; these variables had a sensitivity of 48.3%. The VCG sign of a narrow horizontal QRS loop increased the sensitivity of the ECG-VCG method to 79.3% while maintaining a 100% specificity. In patients with inferior plus anterior myocardial infarction (Group A + B) the signs mentioned above for each group were evaluated, confirming a 100% specificity. Regarding the diagnosis of severe asynergy, the ECG signs had a sensitivity of 61.3%, while VCG increased the sensitivity of the ECG-VCG method to 90.3%.(ABSTRACT TRUNCATED AT 400 WORDS)     

Prognostic value of Q waves, R/S ratio, loss of R wave voltage, ST-T segment abnormalities, electrical axis, low voltage and notching: correlation of electrocardiogram and left ventriculogram

Data on the correlation of left ventricular segmental wall motion and electrocardiographic findings are, except for Q waves and ST segment elevation, still controversial. Therefore, in addition to Q waves and ST segment elevation, eight features of the electrocardiogram were studied in 265 patients, 61 with normal coronary arteries and 204 with coronary artery disease. Patients with a QRS duration of 0.12 second or greater were excluded. Left ventricular wall motion was assessed in the 30 degrees right anterior oblique and the 60 degrees left anterior oblique projections and analyzed by the Stanford method and a modification of that method, respectively. Asynergy of a particular segment correlated well with the presence of Q waves in the corresponding electrocardiographic lead or leads, but was also found in other segments. There was a significant (p less than 0.001) correlation between the number of leads with Q waves and the degree of extension of asynergy. The R/S ratio in lead V1 and Q waves in lead V6 appeared to be the most informative about the posterior wall. Loss of R wave voltage had a lower predictive value for segmental asynergy than did Q waves in the same lead. Among patients with electrocardiographic findings of an infarct, asynergy was found in 83 to 94%. Patients having Q waves in combination with ST segment elevation manifested more severe asynergy than did patients whose Q waves were not associated with ST elevation. New data are presented for lateral and posterior infarction. Patients having left-axis deviation, low voltage and QRS notching had severe asynergy.(ABSTRACT TRUNCATED AT 250 WORDS)     

Diagnostic significance for coronary artery disease of abnormal Q waves in the "lateral" electrocardiographic leads

To determine the diagnostic significance for coronary artery disease of abnormally large Q waves in leads I, aVL, V5 and V6--the "lateral" electrocardiographic leads--the electrocardiograms of 240 patients who had undergone cardiac catheterization were studied. First, the electrocardiograms of 99 subjects proved normal by cardiac catheterization (group 1) were studied to determine the values of the durations of Q waves in leads I, aVL, V5 and V6 that should be exceeded to be considered abnormal. These values were 30, 30, 20 and 25 ms, respectively. Then, 67 patients were identified who had abnormal Q waves in at least 1 of these leads (group 2) and 74 patients with at least 1 angiographic abnormality but without abnormal Q waves in any of these leads (group 3). Group 2 had generally more extensive left ventricular disease and a higher prevalence of anterior, inferior and apical healed myocardial infarction (MI) than group 3. However, compared with group 3, group 2 had lower prevalences of significant narrowing of the coronary arteries that supply the left ventricular lateral wall. Within group 2, abnormal Q waves in leads I and aVL (traditionally designated high lateral MI) were associated with anterior as well as apical MI, and abnormal Q waves in leads V5 and V6 (traditionally designated anterolateral MI) were associated with inferior as well as apical MI. Thus, abnormal Q waves in leads I, aVL, V5 and V6 tend to reflect apical rather than lateral MI and the term anterolateral MI is especially misleading.     

Left ventricular wall motion with and without Q-wave disappearance after acute myocardial infarction

Since post-acute myocardial infarction (AMI) Q waves may disappear independent of reinfarction or development of left bundle branch block, the relation between the presence of Q waves and segmental asynergy was assessed in 58 patients with initial Q waves after first AMI. Two-dimensional (2-D) echocardiograms and electrocardiograms were recorded 1 year later. By electrocardiography, 28 had anterior and 25 inferior AMI. At 1 year Q waves had disappeared in 12 of 53 patients (23%): 5 with anterior and 7 with inferior AMI. Segmental asynergy, however, was present in 9 of these 12 patients, although dyskinesia was absent. Presence of Q waves at 1 year (41 patients) was always associated with segmental asynergy. Wall motion score, based on degree of segmental asynergy, was higher in the 41 patients with Q waves compared with patients in whom Q waves disappeared (7.8 +/- 4.4 vs 2.7 +/- 1.9, p less than 0.001). In patients with anterior AMI the number of Q waves at 1 year and the grade of asynergy were correlated. Segmental dyskinesia was rare in patients with inferior AMI (1 of 25) but was common in those with anterior AMI (18 of 28), and was consistently present in patients with more than 2 anterior Q waves.     

Echocardiographic and electrocardiographic aspects indicative of necrosis caused by isolated disease of the right and circumflex coronary artery

The value of 12-lead electrocardiogram (ECG) and two-dimensional echocardiography (2D-ECHO, wall motion abnormalities) in recognizing myocardial infarction due to left circumflex and right coronary artery disease was evaluated in 75 patients (aged 26-69 years, within 3 months of myocardial infarction) with single vessel disease (luminal stenosis greater than or equal to 70%). Twenty-five patients (pts) had left circumflex disease and 50 right coronary artery disease. In the group of pts with left circumflex disease, 13 (52%)--group I--showed asynergy limited to the postero-lateral wall and 12 pts (48%)--group II--had more extensive asynergy involving both the postero-lateral and the infero-posterior wall. No pts with left circumflex disease demonstrated asynergy of the interventricular septum. Good correlations were found between the site and extent of asynergy and the location of left circumflex narrowings: 9--group I pts--(69.2%) had obtuse marginal branch disease and 8--group II pts--(67%) had proximal left circumflex disease. Patients with right coronary artery disease were subdivided as follows: group I: 35 pts (70%) with asynergy of infero-posterior wall and posterior septum; group II: 11 pts (22%) with extensive asynergy of infero-posterior, postero-lateral walls and posterior septum; group III: 4 pts (8%) with asynergy limited to the infero-posterior wall. The location of right coronary artery narrowings had no relation to the site and extent of infarct asynergy in pts with single right coronary artery disease.(ABSTRACT TRUNCATED AT 250 WORDS)     

Lack of superiority of the vectorcardiogram over the electrocardiogram in detecting inferior wall myocardial infarction regardless of time since infarction

Using more recent VCG and ECG criteria, the relative accuracy of these two tests in detecting inferior wall MI over time was evaluated in 38 of 236 patients undergoing elective left ventriculographic and coronary angiographic studies who had clinical plus angiographic evidence of inferior wall myocardial infarction. The overall sensitivity and specificity of the ECG criteria of the New York Heart Association and Warner did not differ from that of the VCG criteria of Starr and Takatsu. There was a trend toward decreased sensitivity in both VCG criteria and the ECG criterion of Warner in detecting inferior wall myocardial infarction greater than or equal to 18 months, although the difference did not reach statistical significance. Changing the age of infarction to greater than or equal to 3, greater than or equal to 6, greater than or equal to 12, or greater than or equal to 24 months did not yield a different result. It is concluded that VCG is not superior to ECG in the diagnosis of inferior wall MI regardless of time since occurrence of infarction.     

The effect of the localization of Q wave myocardial infarction on ventricular electromechanics

BACKGROUND: The exact location of a Q wave myocardial infarction has an important effect on overall left ventricular function. OBJECTIVES: To assess the effect of localization of Q wave infarction on left ventricular minor and long axis function, with particular reference to electromechanical disturbances. METHODS: We studied 72 patients with Q wave myocardial infarction; 35 anterior, age 61+/-15 years and 37 inferior, age 62+/-12 years. ECG intervals were automatically measured by Hewlett-Packard Pagewriter and LV dimension and filling velocities studied by transthoracic echocardiography and simultaneous phonocardiogram. Findings were compared with 21 controls of similar age. RESULTS: Heart rate and all ECG intervals were similar in the two patient groups and controls. QRS axis was more to the left in patients with inferior MI. Normal septal q wave was absent in lead V5 and V6 in 33/35 (94%) patients with anterior MI and in only 3/37 (8%) with inferior MI, p<0.001. LV minor axis dimensions were enlarged vs. normal (p<0.001) in the two patient groups and to a greater extent in anterior MI compared with inferior MI, p<0.05. Isovolumic relaxation time was prolonged only in-patients with an inferior MI, p<0.01. Long axis amplitude was globally reduced (p<0.001) in the two patient groups as were shortening and lengthening velocities (p<0.001). The onset of septal long axis shortening with respect to the q wave was delayed by 30 and 40 ms in inferior MI and anterior MI and that of lengthening with respect to A2 by 20 and 30 ms, respectively, compared to normal (p<0.001 for both). Post ejection shortening was localized to the septal long axis in 32/35 patients with anterior MI but was generalized involving all three LV long axes in inferior MI, p<0.001. Transmitral Doppler flow velocities and the frequency of mild mitral regurgitation were similar in the two groups. CONCLUSION: These results confirm a close association between anterior Q wave infarction, septal incoordination and absent septal q waves. The global incoordinate long axis behaviour in inferior Q wave MI may be due to significant papillary muscle dysfunction, and results in significant shape change in early diastole. This disturbance in electromechanical behaviour might play an important role in the differing outcomes between the two different sites of myocardial infarction.     

右胸头胸导联心电图病理性Q波意义探讨

描记１３５例（正常人２２例，心绞痛１４例，非Ｑ波梗塞１０例，前壁梗塞２５例，下壁右室梗塞３６例）右胸头胸导心电图ＨＶ３Ｒ－ＨＶ７Ｒ，发现前３组共４６例右胸心电图正２２例（８８％），３例有左前降支冠脉闭塞，左室扩大合并心室壁瘤患者，ＨＶ３Ｒ，ＨＶ４Ｒ出现Ｑ波，ＨＶ５Ｒ－ＨＶ７Ｒ正常。下壁梗塞组心电图正常５例（１８％），Ｑ波主要分布在ＨＶ５Ｒ－ＨＶ７Ｒ。下壁合并右室梗塞组全部病例ＨＶ６Ｒ，ＨＶ７Ｒ均含     

Diagnostic value of Q waves outside standard precordial lead points in left anterior myocardial infarction undetectable by standard 12-lead electrocardiogram

Body surface potential maps were recorded for 52 patients with solitary anterior myocardial infarction and 57 normal subjects. All patients had pure anterior wall asynergy on a left ventriculogram but no diagnostic Q wave on the standard 12-lead electrocardiogram. Q wave (greater than 30 msec) distributions on the body surface of the patients and normals were compared. The frequency of Q waves in the area above V1-V2 and in the right middle chest was significantly higher in patients than in normals. The sensitivity of Q waves for asynergy in leads from both these areas was 19-60%. The positive predictive value was 67-94%. The frequency of Q waves was significantly higher in severe asynergy than in mild asynergy. A combination of two selected unipolar leads from these areas yielded a sensitivity and specificity of 33% and 95%, respectively. With a combination of three leads, these values were 42% and 93% and with four leads 48% and 88%, respectively. The results indicate that several unipolar leads from the area above V1-V2 and from the right middle chest in addition to the standard 12-lead electrocardiogram may improve the electrocardiographic diagnostic accuracy of myocardial infarction.     

Evaluation of a QRS scoring system for estimating myocardial infarct size. VI: Identification of screening criteria for non-acute myocardial infarcts

Each of the 54 criteria in the Selvester 32-point QRS scoring system for estimation of myocardial infarct (MI) size has attained greater than or equal to 95% specificity in normal subjects. This study was performed to identify a subset of those criteria with cumulative specificity greater than or equal to 95% and maximal sensitivity for use in screening for the presence of non-acute MI. Coronary angiography and left ventriculography were used to identify 500 normal subjects, 60 patients with isolated anterior MI and 62 patients with isolated inferior MI. Patients with the QRS confounding factors of ventricular hypertrophy, fascicular block or bundle branch block on their electrocardiogram were not included. Using stepwise logistic regression analysis, the screening criteria identified were: (1) Q greater than or equal to 30 ms in aVF, (2) R less than or equal to 10 ms and less than or equal to 0.1 mV in V2 and (3) R greater than or equal to 40 ms in V1. Cumulatively, these 3 screening criteria achieved 84% and 77% sensitivities for inferior and anterior MI groups, respectively. Thus, a set of 3 criteria from the Selvester QRS scoring system is capable of identifying single non-acute anterior or inferior MI in 80% of patients, and falsely indicating presence of MI in only 5% of normal subjects.     

The time course in acute myocardial infarction evaluated with precordial mapping and standard ECG

Fifty-six patients with acute transmural anterior wall myocardial infarction (MI) were investigated with a 24-electrode grid and 34 patients with an acute transmural inferior wall MI were investigated with standard ECG leads II, III, and aVF in order to study the length of time after the onset of pain during which the development of Q waves and reduction of R waves progress. These ECG changes continued for 18-26 h after onset of pain but the majority appeared during the first 12 h.     

DIAGNOSIS OF INFERIOR MYOCARDIAL INFARCTION IN THE PRESENCE OF LEFT ANTERIOR HEMIBLOCK

Inferior myocardial infarction results in Q waves in the inferior leads of the electrocardiogram (ECG). Left anterior hemiblock results in initial r waves in these leads. Thus the diagnosis of one in the presence of the other is difficult. It has been reported that inferior infarction can be diagnosed in the presence of left anterior hemiblock when there is a q wave or q equivalent in lead II, and that part of the inferior wall must be spared, to result in the initial r waves of left anterior hemiblock in leads III and aVF. We examined these concepts in 18 patients with such an ECG, by means of resting myocardial perfusion (thallium-201) scintigraphy. In 15 there were defects in the inferior left ventricular wall consistent with inferior infarction. In all of these patients there was sparing of part of the inferior wall: in nine, sparing of the posterior part, and in six, sparing of the anterior part. We conclude that in apparently isolated left anterior hemiblock, a q wave or q equivalent in lead II is an important sign, indicating the likelihood of associated inferior infarction.