Negative post-ischemic T waves in variant angina

The clinical and prognostic significance of negative T waves on the basal electrocardiograms of patients with unstable angina has been recently investigated with controversial results. Moreover, there is little data regarding this phenomenon in patients with variant angina. In order to evaluate the significance of negative post-ischemic T waves in patients with variant angina, 72 patients underwent Holter recording and coronary angiography. Negative T waves were present in 38 out of 72 patients (53%): they were anterior in 24 cases and inferior in 14 cases. The negative T-wave phenomenon was present in 29 patients on admission and showed up in 9 patients during hospitalization. Holter recording showed no significant differences between patients with or without negative T waves with regards to: 1) the proportion of symptomatic transient myocardial ischemic attacks; 2) the frequency of arrhythmias during transient myocardial ischemic attacks; 3) the maximum duration of transient myocardial ischemic attacks; 4) the maximum degree of ST elevation during transient myocardial ischemic attacks. Negative T waves on the anterior leads showed a moderate sensitivity (54%) and total predictive accuracy (52%), as well as a lower specificity (43%) and negative predictive accuracy (15%) for a significant stenosis of the left anterior descending coronary artery. This was due to the presence of several patients with left anterior descending artery stenosis and without negative T waves. On the other hand, negative T waves on the inferior leads were characterized by high sensitivity (85%), specificity (80%) and total predictive accuracy (82%) for a significant stenosis of the right coronary artery and/or the circumflex artery.(ABSTRACT TRUNCATED AT 250 WORDS)     

Persistent T-wave inversion in unstable angina: the correlation with the global and regional function of the left ventricle]

The correlation between persistent negative T wave on basal electrocardiogram and coronary anatomy or global and regional left ventricular function was investigated in 34 patients with unstable angina defined as new onset (< 2 months), crescendo or rest angina. The patients with history of previous myocardial infarction, pathological Q waves on electrocardiogram or documented elevation of CPK were excluded. Eighteen patients (group A) showed T wave inversion (> 1 mV) in at least two leads on the basal electrocardiogram, persisting for at least 48 hours before coronary arteriography. In 16 patients (group B) the basal electrocardiogram was normal. Left ventricular volumes and ejection fraction were calculated and the regional systolic wall motion was analyzed using the area method in the 30 degrees right anterior oblique view. Hypokinesis was defined as more than 2 standard deviation below the mean value calculated in 24 normal subjects. No difference was present for age (A: 61 +/- 9 vs B: 57 +/- 9 yrs) and sex distribution. Critical stenoses of at least one coronary artery was documented in all but one patient (in group B). The number of critical stenosis per patient was equal (1.8) in the two groups. Left main coronary artery showed narrowing > 50% in three patients of group A and in two patients of group B.(ABSTRACT TRUNCATED AT 250 WORDS)     

The appearance of giant negative T waves in anterior acute myocardial infarct with a Q wave is associated with minor myocardial damage and a minor extension of coronary disease]

INTRODUCTION AND OBJECTIVE: The early inversion of T waves in patients with acute myocardial infarction has recently been related to a better left ventricular function and a more favourable evolution, contrary to what happens in the unstable angina. On the other hand, the significance of the appearance of deep negative T waves in the early phase of some acute myocardial infarction is not known. The aim of this study is to evaluate its relation with the existing myocardial damage and the underlying coronary artery disease extension in anterior some with Q wave. METHODS: 48 patients with a first anterior Q-wave acute myocardial infarction, thrombolized or not, admitted to hospital with an evolution of less than 24 hours, and with a coronariography performed before discharge were analyzed. Giant negative T waves were defined as those which were 8 mm or more from baseline. RESULTS: 17 of the 48 patients presented giant negative T waves (T-group) and 31 did not (N-group). In the T-group patients, the size of the negative T wave was 11.29 +/- 2.86 mm and the number of precordial leads with negative T waves was 4.35 +/- 1.57. There were no differences between both groups in variables such as sex, coronary risk factors, and other basal characteristics. The T-group patients were younger, had lower peak-CK, CK-MB and LDH levels and presented greater recovery of R waves during the follow-up, the differences being significant with the N-group patients. The left ventricular ejection fraction was higher (56.3 +/- 13.4 vs 42 +/- 12%; p < 0.001) and the number of affected coronary vessels was lower in the T-group (1.12 vs 1.64; p < 0.01); there were no differences in the localization or severity of coronary lesions, nor in the frequency of postinfarction myocardial angina. None of the patients in the T-group were Killip > I, while this situation occurred in 38.7% of the N-group patients. CONCLUSIONS: The appearance of giant negative T waves in the acute or early phase of Q-wave anterior acute myocardial infarction is associated with a smaller infarct size, lower functional deterioration and less extension of the underlying coronary disease.     

New diagnostic evidence on the T wave map indicating involved coronary artery in patients with angina pectoris

To define the clinical significance of T wave map changes in patients with angina at rest, body surface isopotential T distributions were obtained in 48 patients with single-vessel disease (left anterior descending artery, 34; right coronary artery, eight; left circumflex artery, six) documented angiographically and were compared with those in 120 healthy subjects and those in 19 patients with left ventricular overload whose electrocardiograms showed negative T waves accompanied by an increase in R wave amplitude in left precordial leads. The T wave map abnormalities were observed in 24 of 48 patients (50%) with angina and were classified into three types: (1) type I (18 patients, 37.5%) was characterized by a segmental negative potential in the positive area located at the left thorax and the minimum at the peak of T wave positioned in the upper portion of the left anterior chest, (2) type II (three patients, 6.3%) was characterized by a negative potential with a minimum in the inferior thorax and an indentation of negative potential at the lower margin of the positive potential located over the upper thorax, and (3) type III (three patients, 6.3%) was characterized by a negative potential with a minimum at the back throughout the period of T wave. All patients showing T wave map abnormalities of type I had a significant stenosis of the left anterior descending artery. Likewise, all patients with type II or III had single-vessel disease of the right coronary or left circumflex artery, respectively. All types of T wave map changes observed in patients with angina were different from those in patients with left ventricular overload, whose maps showed the generalized negative potential at the inferior thorax and the left back and the minima clustered at the precordium. In seven patients with lesions of the left anterior descending artery, T wave map abnormalities of type I recovered to normal after successful percutaneous transluminal coronary angioplasty. The behavior of the negative potential and its extrema on the T wave map, which was not available from routine electrocardiography, was indicative of the involved coronary artery and probably of its associated ischemic area in one-half of our patients with angina pectoris.     

Natural course of electrocardiographic components and stages in the first twelve hours of acute myocardial infarction

Time course evolution of R, Q, T and ST components of the electrocardiogram during the first 12 hours of an acute myocardial infarction was studied. A comparison between anterior-extensive and anteroseptal wall infarctions (anterior group), and inferior-extensive and inferior wall infarction (inferior group) showed appearance of significant Q waves within two hours in both groups. R wave loss was nearly a mirror image of Q wave development in both groups. T waves became negative and ST more isoelectric earlier in the inferior than in the anterior group. When combined variations of the four electrocardiographic components were analyzed, four stages of acute infarction were delineated. Stage I--tall R, no Q, ST elevation and positive T; Stage II--significant Q wave appearance; Stage III--negativity of T waves; and Stage IV--ST isoelectric. The inferior group reached stages III-IV within 12 hours; the anterior group remained mostly in stage II. An early appearance of Q waves correlated well with rapid progression to stages III-IV within 12 hours in both infarction groups.     

Electrocardiographic prediction of the development and site of acute myocardial infarction in patients with unstable angina

BACKGROUND: ST-T changes on 12-lead electrocardiograms (ECGs) in patients with unstable angina (UA) have limited values for prediction of subsequent acute myocardial infarction (AMI). The aim of the present study is to obtain more useful ECG signs during UA in predicting the risk and the site of AMI. METHODS: ECGs were recorded from 238 consecutive patients with UA; 149 developed AMI, whereas 89 did not in the following 60 days after the UA episodes. P, ST-T and U wave changes in these AMI and non-AMI patients were analyzed retrospectively. Three groups of ECG leads were referred to reflect ischemic changes of anterior (V1-V5), lateral (I, aVL and V6) and inferior (II, III, and aVF) left ventricular walls. To explore the site-dependent predictors, the 149 AMI patients were divided into two groups; group A/L with anterior, antero-septal, apical or lateral AMI, versus group I/P with inferior or posterior AMI. RESULTS: ST depression > or =1 mm and abnormal T wave or U wave changes and P wave abnormalities were observed more frequently in AMI patients than non-AMI patients. On multivariate analysis, an independent ECG finding of the development of AMI was a biphasic U wave (odds ratio (OR) 5.4, 95% confidence interval (CI), 1.9-15.6, P=0.002) in the anterior leads. An inverted T wave (OR 5.1, 95%CI, 1.7-15.5, P=0.0036) and a biphasic U wave (OR 6.0, 95%CI, 2.2-16.1, P=0.0004) in the anterior leads were independent predictors of AMI in group A/L. There was no independent ECG predictor of group I/P. CONCLUSIONS: Biphasic U wave in anterior leads during UA is a useful ECG observation in the risk stratification of subsequent AMI. The independent ECG predictors of antero-lateral MI are inverted T wave and biphasic U wave.     

心尖肥厚型心肌病的心电图特征

分析１０例心尖肥厚型心肌病的心电图。９例Ｖ３－Ｖ６Ｒ波异常高大，尤以Ｖ３－Ｖ５，为甚，伴Ｔ波倒置。内８例呈巨大倒置Ｔ波。６例２４小时动态心电图２例活动平板心电图运动试验心率增快时Ｔ波倒置无变化。     

巨大负性T波患者冠心病的预测影响因素

目的：探讨心电图巨大负性T波在冠心病诊断中的预测价值。方法：回顾性分析1998年1月至2001年12月64例心电图示巨大负性T波并在我院行冠状动脉造影检查的患者，对其心电图、超声心动图和临床资料进行统计分析。结果：心电图示无左心室肥厚或表现为对称性巨大负性T波则支持冠心病的诊断。巨大负性T波患者心电图缺乏左心室肥厚较对称性T波倒置对冠心病更有预测价值。结论：心电图巨大负性T波患者不伴左心室肥厚或对称性T波倒置是预测冠心病的重要因素。     

Electrocardiographic manifestations of proximal left anterior descending artery occlusion

We report the case of a 51-year-old woman who presents with a 2-week history of episodes of pressure like chest pain. The initial electrocardiogram was not indicative of myocardial ischemia or infarction and the cardiac enzymes remained normal during the initial hospital day. However, the precordial T waves inverted and progressively deepened on the second hospital day and the patient underwent cardiac catheterization with percutaneous coronary angioplasty and stent placement of the left anterior descending coronary artery with good results. The postprocedure electrocardiogram showed complete resolution of the inverted precordial T waves. The development of new T-wave inversions in the precordial leads of patients presenting with unstable angina is predictive of significant stenosis of the left anterior descending coronary artery. This subgroup of patients has a poor prognosis if medical therapy alone is instituted. Early cardiac catheterization and revascularization is recommended for these patients. Evidence has shown that 75% patients with these electrocardiogram changes who are not revascularized developed extensive anterior wall infarction within a few weeks.     

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.     

Value of negative U waves in coronary artery spasm

The significance of U-wave inversion during coronary arterial spasm was investigated in 188 consecutive ergometric tests performed in 69 patients. All patients had previously undergone coronary arteriography which had clearly shown coronary spasm either at rest or after a single 0.4 mg injection of ergometrine. The ergometrine tests were then performed at the patient's bedside using a standard protocol with injection of incremental doses of ergometrine: 0.05, 0.1, 0.2 and 0.4 mg every 5 minutes with 12-lead ECG recordings every minute. Fifty of the 59 patients with positive tests had classical signs of spasms: ST elevation or depression and/or T wave inversion; the other 9 patients had inversion of the U wave alone (2 cases) or associated with classical ST segment changes in the remaining cases. The 10 other patients had no ECG changes although 2 of them suffered typical anginal pain. Negative U waves were observed in 4 of the 12 patients with spasm of the left anterior descending artery, accompanied by ST elevation in the anterior wall leads. A negative U wave would appear to be a sign of less ischaemia than the classical ECG changes because anginal pain is less common: 4 out of 9 cases in which U wave inversion was a very early change, 8 out of 9 cases in which it was the first or only abnormality. The recognition of a negative U wave increases the sensitivity of the electrocardiogram during resting angina and allows earlier treatment of coronary spasm with nitrate derivatives after an ergometrine test.     

T wave positivity in resting electrocardiogram predicts preserved systolic thickening in chronic anterior Q wave myocardial infarction: an echocardiographic study.

AIM: After ST elevation myocardial infarction, ST segment and T wave changes generally resolve, but in some patients T waves keep their negative components for a long time. The aim of this study is to evaluate the pathophysiological implications of persistent negative T waves and restored positive T waves in the chronic stage of Q wave myocardial infarction. METHODS: We studied 30 patients with a previous anterior wall ST elevation myocardial infarction (more than one year follow-up) and presenting Q waves in at least three consecutive precordial leads in the standard 12-lead electrocardiogram at rest. Patients were divided into two groups according to the T wave pattern in leads with Q waves: positive T group consisting of patients in whom all T wave components showed an upright configuration; and a negative T group consisting of patients in whom T waves were are least partly inverted. We used echocardiography to measure systolic thickening of the interventricular septum within the infarction area. Systolic thickening was considered significant when end-systolic thickness was greater than end-diastolic thickness by > 25% in proportion and > 1 mm in absolute value. RESULTS: Significant systolic thickening was demonstrated in 14 (74%) of the 19 positive T patients and in one (9%) of the 11 negative T patients (odds ratio 8.1; 95% CI, 1.2 to 53.5; p = 0.002). CONCLUSION: In the chronic stage of a myocardial infarction, restored T wave positivity predicts preserved systolic thickening, suggesting the presence of viable and normally contracting myocytes within the infarction area. Further studies are needed to establish the prognostic value of T wave characteristics in patients with a past history of myocardial infarction.     

U wave inversion during attacks of variant angina.

Sequential 12 lead electrocardiograms were recorded during angina pectoris induced by ergonovine maleate in 38 patients with variant angina. Transient U wave inversion was observed in 17 patients with ST segment elevation in anterior chest leads, but in only three of 21 patients with ST segment elevation in the inferior leads associated with right coronary artery spasm. In the 17, all of whom had spasm of the left anterior descending coronary artery, the sensitivity of ST segment elevation in V5 was only 41%, and that of U wave inversion 71%. U wave inversion without ST segment elevation occurred during attacks in 35% of patients. During the recovery phase, the sensitivity of U wave inversion was 82% in V4 and 65% in V5, though ST segment elevation was absent in both V4 and V5. Thus, inverted U waves without ST segment elevation often appear in marginal ischaemic zones or during the time of recovery from temporary ischaemia. Detection of inverted U waves should aid in the diagnosis of variant angina when only lead V5 is used as a monitor and when electrocardiograms are recorded only during the recovery phase.     

心电图对非ST段抬高型急性冠脉综合征危险分层的价值

目的探讨心电图变化对非ST段抬高型急性冠状动脉综合征患者危险分层的价值。方法自2006年1月-2007年7月，在我院因急性胸痛拟诊不稳定型心绞痛及非ST段抬高心肌梗死而收入住院且记录资料完整的616例患者。人院后采集病史、查体，并在10min内完成常规18导联心电图检查，将患者人院时心电图的改变分为ST段压低组（包括伴有T波倒置者）、单纯T波倒置组、尚不能诊断的心电图组及正常心电图组；又将ST段压低组分为：胸前导联（V4-V6）ST段压低合并负向T波、胸前导联ST段压低合并正向T波、其他导联ST段压低合并正向T波、其他导联ST段压低合并负向T波4组。观察各组住院期主要心血管事件（心脏性死亡、非致命性心肌梗死、反复缺血性心绞痛发作），并随访1-12（7．2±3．8）个月，观察主要心血管事件变化。结果与正常心电图组比较；ST段压低组的复合心血管事件明显增多。胸前导联ST段压低合并T波倒置组的患者较其他导联ST段压低合并或不合并T波倒置组的复合心血管事件明显增多。结论．心电图的ST段变化对非ST段抬高型急性冠状动脉综合征患者的危险分层及心血管事件预测均有重要价值。     

The prognostic significance of T‐wave inversion according to ECG lead group during long‐term follow‐up in the general population

BackgroundInverted T waves in the electrocardiogram (ECG) have been associated with coronary heart disease (CHD) and mortality. The pathophysiology and prognostic significance of T‐wave inversion may differ between different anatomical lead groups, but scientific data related to this issue is scarce.MethodsA representative sample of Finnish subjects (n = 6,354) aged over 30 years underwent a health examination including a 12‐lead ECG in the Health 2000 survey. ECGs with T‐wave inversions were divided into three anatomical lead groups (anterior, lateral, and inferior) and were compared to ECGs with no pathological T‐wave inversions in multivariable‐adjusted Fine–Gray and Cox regression hazard models using CHD and mortality as endpoints.ResultsThe follow‐up for both CHD and mortality lasted approximately fifteen years (median value with interquartile ranges between 14.9 and 15.3). In multivariate‐adjusted models, anterior and lateral (but not inferior) T‐wave inversions associated with increased risk of CHD (HR: 2.37 [95% confidence interval 1.20–4.68] and 1.65 [1.27–2.15], respectively). In multivariable analyses, only lateral T‐wave inversions associated with increased risk of mortality in the entire study population (HR 1.51 [1.26–1.81]) as well as among individuals with no CHD at baseline (HR 1.59 [1.29–1.96]).ConclusionsThe prognostic information of inverted T waves differs between anatomical lead groups. T‐wave inversion in the anterior and lateral lead groups is independently associated with the risk of CHD, and lateral T‐wave inversion is also associated with increased risk of mortality. Inverted T wave in the inferior lead group proved to be a benign phenomenon.     

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.     

Large T wave inversion and QT prolongation associated with pulmonary edema: a report of nine cases.

OBJECTIVES: The purpose of this study is to describe a new clinical electrocardiographic phenomenon characterized by diffuse symmetrical T wave inversion and QT prolongation after recovery from an episode of cardiogenic but nonischemic pulmonary edema. BACKGROUND: A variety of clinical conditions, but not acute pulmonary edema, have been previously associated with giant negative T waves and QT prolongation in the postevent electrocardiogram. METHODS: In nine patients not suspected of having ischemic heart disease, new large or global T wave inversion with QT prolongation was observed after resolution of acute cardiogenic pulmonary edema. Each patient underwent detailed clinical evaluation including testing for myocardial injury and a coronary ischemic etiology. RESULTS: There were seven women and two men with ages ranging from 32 to 79 years. The etiology of pulmonary edema was diverse, but acute myocardial infarction and significant coronary artery disease were ruled out in each case. During the index event, most patients had elevated blood pressure, sinus tachycardia, minimal nonspecific ST and T wave changes and normal QT intervals. Large inverted T waves with marked prolongation of the QT intervals evolved within 24 h after clinical stabilization. The electrocardiographic changes gradually resolved in one week. There was no in-hospital mortality. CONCLUSIONS: Acute cardiogenic but nonischemic pulmonary edema may cause deep T wave inversion and QT prolongation after resolution of the symptoms. The repolarization abnormalities may last for several days. These electrocardiographic changes do not adversely effect short-term prognosis.     

Anatomic and prognostic significance of new T-wave inversion in unstable angina

The significance of the development of new T-wave inversion was studied in 118 consecutive patients with unstable angina. The electrocardiograms during hospitalization in the coronary care unit were analyzed for occurrence of new T-wave inversion greater than or equal to 2 mm and correlated with findings at coronary angiography (73 patients) and at follow-up (112 patients). Twenty-nine patients had anterior T-wave inversion. Of these, 25 patients (86%) had greater than or equal to 70% diameter reduction of the left anterior descending (LAD) artery, compared with 11 (26%) of 42 patients without anterior T-wave inversion (p less than 0.001). The sensitivity of T-wave inversion for significant LAD stenosis was 69%, specificity 89%, and positive predictive value 86%. Two patients had T-wave inversion in the inferior leads. Both patients had significant right coronary artery disease, compared with 18 of 55 patients without inferior T-wave inversion (difference not significant [p = NS]. Seventy-one patients who were treated medically had 16 +/- 9 months' follow-up. Of 26 patients who had T-wave inversion, 10 (38%) had cardiac events, compared with 7 (16%) of the remaining 45 patients without T-wave inversion (p less than 0.05). Forty-one patients who had undergone coronary bypass surgery had 19 +/- 9 months' follow-up. Of 22 patients with T-wave inversion, 4 (18%) had cardiac events, compared with 2 (11%) of the remaining 19 patients without T-wave inversion (p = NS). Thus, development of new T-wave inversion greater than or equal to 2 mm in patients with unstable angina (1) is predictive of significant coronary artery stenosis, and (2) identifies a subgroup with poor prognosis when treated medically.     

Reversal of segmental hypokinesis by coronary angioplasty in patients with unstable angina, persistent T wave inversion, and left anterior descending coronary artery stenosis. Additional evidence for myocardial stunning in humans

To evaluate the significance of persistent negative T waves during severe ischemia, we prospectively studied 62 patients admitted for unstable angina without evidence of recent or ongoing myocardial infarction. A critical stenosis on the left anterior descending coronary artery (LAD), considered as the culprit lesion, was successfully treated by percutaneous transluminal coronary angioplasty (PTCA). The patients were divided into two groups according to the admission electrocardiogram: T NEG group (n = 32) had persistent negative T waves, and the T POS group (n = 30) had normal positive T waves on precordial leads. The two groups had similar baseline clinical, hemodynamic, and angiographic characteristics. All patients underwent a complete clinical and angiographic evaluation (coronary arteriography and left ventriculography) before undergoing PTCA and 8 +/- 3 months later. Left ventricular anterior wall motion was evaluated by the percent shortening of three areas (S1, S2, and S3) considered as LAD-related segments on left ventriculograms. Before PTCA, there was no significant difference in global ejection fraction between the two groups despite a significant depression in anterior mean percent area shortening in the T NEG compared with the T POS group (S1, 44 versus 54, p less than 0.01; S2, 39 versus 48, p less than 0.01; S3, 44 versus 50, NS). At repeated angiography, the anterior mean percent area shortening improved significantly in the T NEG group (S1, from 44 to 61, p less than 0.001; S2, from 39 to 58, p less than 0.001; S3, from 44 to 61, p less than 0.001).(ABSTRACT TRUNCATED AT 250 WORDS)     

Magnetocardiographic studies of ventricular repolarization in old inferior myocardial infarction

Isomagnetic maps of 50 normal subjects (control group) and 23 patients with old inferior myocardial infarction (IMI group) were recorded in order to analyse T wave abnormalities in inferior myocardial infarction. The T wave of the magnetocardiogram (MCG) in the control group showed negative deflections in the left upper portion and positive deflections in the right lower portion, thus resulting in a T vector directed leftward and inferiorly. The T wave of the IMI group was flat or positive in the left upper portion and flat or negative in the right lower portion, suggesting a T vector directed superiorly. In addition, opposing dipoles were observed in 36.4% of the IMI group; i.e. one directed superiorly, presumably due to inferior myocardial ischaemia, and the other directed inferiorly due to normal repolarization. Localized T vector abnormalities could be detected by the MCG in some cases, in which coronary T waves of the standard electrocardiogram had returned to normal. Furthermore, multiple dipoles were more frequently observed in the isomagnetic map than in the isopotential map (5 vs. 15; P less than 0.01). These results suggest that the MCG is helpful in diagnosing myocardial ischaemia when this is not detectable on the electrocardiogram.