Relationship between late potentials and the predischarge electrocardiographic pattern in patients with acute anterior wall myocardial infarction

Hypothesis: The presence of late potentials on the signalaveraged electrocardiogram (SAECG) identifies patients at high risk for development of ventricular tachyarrhythmias after myocardial infarction (MI). Methods: The electrocardiogram and left ventricular function in 65 patients recovering from a first acute anterior wall MI were analyzed. We compared the pattern of the ST segment (isoelectric or elevated) and of the T wave (positive or negative) with the SAECG using an orthogonal bipolar lead configuration (X, Y, Z) with bidirectional Butterworth filtering (Simson's method). Results: Abnormal SAECG was found in 17 (26%) patients; 11 of 18 patients with ST elevation had abnormal SAECG, and only 6 of 47 patients with isoelectric ST segment developed abnormal SAECG (p<0.0001, odds ratio = 10.74). Of 19 patients with positive T waves, 10 had abnormal SAECG, and abnormal SAECG was found in 7 of 46 patients with negative T waves (p<0.003, odds ratio = 5.27). When both parameters were considered together, 9 of 12 patients with ST elevation and positive T wave developed abnormal SAECG, and 35 of 40 patients with isoelectric ST and negative T wave had normal SAECG (p<0.0002). Left ventricular ejection fraction was similar in patients with abnormal SAECG (43 ± 14%) and normal SAECG (46 ± 11 %). Conclusion: These findings suggest that patients with anterior wall MI and a predischarge pattern of ST elevation and positive T wave have a higher incidence of abnormal SAECG and therefore may have a worse prognosis, especially related to the subsequent development of ventricular arrhythmias.     

I-123 metaiodobenzylguanidine—thallium-201 mismatch following myocardial infarction

Experimental data show that myocardial infarction (MI) results in regional depletion of myocardial cathecholamines more extensively than necrosis. To investigate the extent of adrenergic denervation post MI in humans, we examined 16 patients, 59 ± 12 years old, with recent (7-12 days) MI. Resting thallium-201 (²⁰¹Tl) single photon emission computerized tomography (SPECT) imaging was performed to assess necrosis; metaiodobenzylguanidine I¹²³ (MIBG) SPECT was used to evaluate adrenergic denervation. ²⁰¹Tl and I¹²³ MIBG defects were evaluated quantitatively using polar maps, and differences in defects were expressed as percent of total polar map. in all patients, I¹²³ MIBG defect was larger than ²⁰¹Tl defect, and difference ranged from 19 to 61 % (39.5 ± 13.2%). Thrombolysis and age > 60 did not influence the difference. Anterior MI showed larger differences (44± 13 vs. 32± 11 %, p < 0.05); patients with ischemic electrocardiographic (ECG) changes in leads without abnormal Q waves had larger differences (45 ± 9 vs. 33 ± 14%, p< 0.05). It was concluded that (a) patients with recent MI present denervation larger than ²⁰¹Tl perfusion defect, and (b) patients with anterior MI and ischemic ECG changes present a larger area of denervation.     

The predictive value of the electrocardiographic pattern of acute q-wave myocardial infarction for recurrent ischemia

Atotal of 140 consecutive patients with acute Q-wave myocardial infarction was evaluated to assess the relationship between different electrocardiographic patterns of evolution and the incidence of recurrent ischemia within 10 days of infarction. Patients were allocated to three groups according to the electrocardiogram at 12 h after admission: Group A: ST elevation of < 2 mm and negative T waves (75 patients); Group B: ST elevation of > 2 mm and negative T waves (35 patients); Group C: ST elevation of > 2 mm and positive T waves (30 patients). Patients in Group C had more anterior wall infarctions (82%) than Group A (40%) or Group B (58%) (p = 0.0001). Peak creatine kinase levels were lower in Group A (782 ± 115 IU) than in Groups B (1415 ± 257 IU) and C (1501 ± 287 IU) (p<0.0001). The occurrence of post-infarction recurrent ischemia was more frequent in Group A (79.2%) than in Groups B (33.3%) and C (14.8%) (p<0.0001). Patients in Group A had relatively smaller infarctions and a higher incidence of recurrent ischemia, whereas patients in Group C had larger infarctions and a lower incidence of recurrent ischemia. The electrocardiographic pattern 12 h after admission for acute myocardial infarction is helpful in identifying a subgroup at high risk of recurrent ischemia.     

ST segment shifts are poor predictors of subsequent Q wave evolution in acute myocardial infarction. A natural history study of early non-Q wave infarction

Acute ST segment elevation is regarded generally as the sine qua non of evolving Q wave myocardial infarction (MI) because such electrocardiographic (ECG) injury is believed to be a marker of transmural ischemia and a forerunner of transmural necrosis. Alternatively, ST segment depression with or without T wave inversion is viewed as the dominant ECG feature of non-Q wave MI. However, this hypothesis has not been assessed prospectively in an acute MI population. We analyzed 2,304 serial ECGs at study entry (admission), day 2, day 3, and predischarge (mean, 10.2 +/- 2 days) from 576 patients with creatine kinase MB confirmed acute non-Q wave MI to determine what percentage of patients with early ST segment elevation culminated in subsequent Q wave development. Of this group, 187 patients (32%) exhibited 1 mm or greater ST segment elevation in two or more contiguous entry ECG leads. Of those patients whose non-Q wave MI could be localized on the basis of diagnostic admission ST segment shifts, the prevalence of early ST segment elevation was 43% (187 of 439). The sum total mean (+/- SD) peak ST segment elevation by lead group (anterior, inferior, lateral) was 4.0 +/- 2.4, 4.5 +/- 2.4, and 2.5 +/- 0.6 mm, respectively. Despite this, only 20% of patients with ST segment elevation (37 of 187) developed Q waves. Of 252 patients who exhibited early ST segment depression or T wave inversion or both, 39 (15%) evolved subsequent Q waves. Thus, while the prevalence of early ST segment elevation in acute evolving non-Q wave MI was higher than previously reported, 80% of patients with and 85% of patients without ST segment elevation and absent Q waves on the admission ECG did not develop subsequent Q waves during a 2-week period of observation (p = NS). In addition, when patients with ST segment elevation were compared with patients with ST segment depression or T wave inversions or both, there were no between-group differences in log peak creatine kinase (404 vs. 383 IU), reinfarction (6% vs. 8%), postinfarction angina (50% vs. 42%), or early recurrent ischemia (49% vs. 45%), defined as postinfarction angina with transient ECG changes. Thus, in patients who present with initial acute non-Q wave MI, ST segment shifts on admission are unreliable predictors of subsequent Q wave evolution and do not discriminate significant differences in postinfarction outcome. In particular, ST segment elevation during the early hours of evolving infarction is not an invariable harbinger of subsequent Q wave development.     

Early T wave inversion after thrombolytic therapy predicts better coronary perfusion: Clinical and angiographic study

Objectives. This study was undertaken to test the hypothesis that early inversion of T waves after thrombolytic therapy for acute myocardial Infarction predicts patency of the infarct-related artery with high Thrombolysis in Myocardial Infarction (TIMI) perfusion flow and better in-hospital outcome.Background. Although numerous studies have demonstrated a strong association between early resolution of ST segment elevation after acute myocardial infarction and successful thrombolysis, little is known about early changes in T waves after thrombolytic therapy.Methods. Ninety-four consecutive patients with acute myocardial infarction treated with recombinant tissue-type plasminogen activator (rt-PA) were studied with admission and predischarge radionuclide ventriculography and with coronary angiography within 72 h of admission. Patient stratification was based on the presence or absence of early (within 24 h) T wave inversion.Results. Early T wave inversion was associated with a higher patency rate of the infarct-related artery (90% vs. 65%, p < 0.02) and less severe residual stenosis ([mean ± SD] 73 ± 27 vs. 83 ± 22, p = 0.06), and when only TIMI perfusion grade 3 was considered, the difference was even greater (77% vs. 41%, p < 0.001). Patients with early inversion of T waves had a lower peak creatine kinase value ([mean ± SD] 678 ± 480 vs. 1,076 ± 620, p < 0.01), and although a similar percent of patients with and without early T wave inversion had a normal ejection fraction (≥55%) on admission, a higher percent of patients with early inversion had a normal ejection fraction at hospital discharge (71% vs. 44%, p < 0.03). Early T wave inversion anticipated a more benign in-hospital clinical course with a lower incidence of adverse cardiac events (10% vs. 33%, p < 0.02).Conclusions. Early inversion of T waves in patients with acute myocardial infarction treated with thrombolytic therapy suggests patency of the infarct-related artery, better perfusion grade and left ventricular function and a more benign in-hospital course.     

Complications of care in a medical intensive care unit

Objective:To determine the frequency and nature of complications of care in the medical intensive care unit (MICU). Design:Prospective, observational study. Setting:Seven-bed MICU in a teaching and referral VA hospital. Patients:295 consecutive patients admitted to the MICU during a ten-month study period. Interventions:None. Measurements and main results:Forty-two patients (14%, 95% confidence interval 13%, 16%) experienced one or more complications during their MICU stays. Compared with other MICU patients, those experiencing complications tended to be older (mean age ± SD: 63.6±10.1 years vs 59.3±14.0 years, p<0.02) and more acutely ill (mean Acute Physiology Score ± SD: 18.3±8.0 vs 12.5±8.0, p=0.0001). These patients also had significantly longer MICU lengths of stay (mean ± SD: 12.3±14.7 days vs 3.1±4 days, p<0.0001) and higher hospital mortality rates (67% vs 27%, p<0.001). The 67% mortality rate among patients with complications significantly exceeded the expected mortality rate of 46% (calculated from the APACHE risk equation). Conclusion:Complications of care in the MICU are not rare and may independently contribute to in-hospital mortality. The potential for complications must be recognized when considering ICU care.     

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.     

Long-term prognosis of young patients after myocardial infarction in the thrombolytic era

Background: Myocardial infarction (MI) in young adults is a rare event. In the Framingham study, the 10-year incidence rate of MI per 1,000 was 12.9 in men 30–34 years old. Overall, 4–8% of patients with acute MI are ≤ 40 years old. Hypothesis: It was the purpose of this study to assess the in-hospital and long-term morbidity and mortality in patients ≤40 years old with acute myocardial infarction compared with older patients in the thrombolytic era. Methods: A consecutive series of 75 patients aged ≤40 years (mean 35.0 ± 4.8) with acute myocardial infarction was compared with an equally sized group of patients aged >40 years (mean 65.1 ± 9.8). Results: Thrombolysis or direct percutaneous transluminal coronary angioplasty was performed in 52 versus 24% (p = 0.0004) and 5.3 versus 2.7% (p = NS) in younger and older patients, respectively. Significantly fewer young patients had multivessel disease (28 vs. 64%, p < 0.004). No in-hospital mortality was observed in patients with reperfusion therapy irrespective of age. After a mean followup time of 47 ± 35 months, cardiac mortality was 0 and 11% (p < 0.03), respectively, in young and older patients with, and 3 versus 24% (p < 0.02) without reperfusion therapy, respectively. In addition, significantly fewer patients in the younger age group developed recurrent angina pectoris (12 vs. 39%, p = 0.0004) or congestive heart failure (9 vs. 34%, p = 0.0005) irrespective of reperfusion therapy. Conclusion: Our observations demonstrate that long-term prognosis after myocardial infarction in young patients is excellent in the thrombolytic era.     

Prognostic significance of ST segment depression in lateral leads I, aVL, V5 and V6 on the admission electrocardiogram in patients with a first acute myocardial infarction without ST segment elevation

OBJECTIVESWe sought to investigate the short-term prognostic value of the admission electrocardiogram (ECG) in patients with a first acute myocardial infarction (MI) without ST segment elevation.BACKGROUNDST segment depression on hospital admission predicts a worse outcome in patients with a first acute MI, but the prognostic information provided by the location of ST segment depression remains unclear.METHODSIn 432 patients with a first acute MI without Q waves or ≥0.1 mV of ST segment elevation, we evaluated the ability of the initial ECG to predict in-hospital death.RESULTSThe presence, magnitude and extent of ST segment depression were associated with an increased mortality, but the only electrocardiographic variable that was significant in predicting death after adjusting for baseline predictors was ST segment depression in two or more lateral (I, aVL, V₅, or V₆) leads (odds ratio 3.5, 95% confidence interval 1.2 to 10.6). Patients with lateral ST segment depression (n = 91, 21%) had higher rates of death (14.3% vs. 2.6%, p < 0.001), severe heart failure (14.3% vs. 4.1%, p < 0.001) and angina with electrocardiographic changes (20.0% vs. 11.6%, p = 0.04) than did the remaining patients, even though they had similar peak creatine kinase, MB fraction levels (129 ± 96 vs. 122 ± 92 IU/liter, p = NS). In contrast, ST segment depression not involving the lateral leads did not predict a poor outcome. Among patients who were catheterized, those with lateral ST segment depression had a lower left ventricular ejection fraction (57 ± 12% vs. 66 ± 13%, p = 0.001) and more frequent left main coronary artery or three-vessel disease than did the remaining patients (60% vs. 22%, p < 0.001).CONCLUSIONSIn patients with a first non–ST segment elevation acute MI, ST segment depression in the lateral leads on hospital admission predicts a poor in-hospital outcome.     

Prognostic significance of ST segment depression in lateral leads I, aVL, V5 and V6 on the admission electrocardiogram in patients with a first acute myocardial infarction without ST segment elevation

OBJECTIVES

We sought to investigate the short-term prognostic value of the admission electrocardiogram (ECG) in patients with a first acute myocardial infarction (MI) without ST segment elevation.

BACKGROUND

ST segment depression on hospital admission predicts a worse outcome in patients with a first acute MI, but the prognostic information provided by the location of ST segment depression remains unclear.

METHODS

In 432 patients with a first acute MI without Q waves or ≥0.1 mV of ST segment elevation, we evaluated the ability of the initial ECG to predict in-hospital death.

RESULTS

The presence, magnitude and extent of ST segment depression were associated with an increased mortality, but the only electrocardiographic variable that was significant in predicting death after adjusting for baseline predictors was ST segment depression in two or more lateral (I, aVL, V₅, or V₆) leads (odds ratio 3.5, 95% confidence interval 1.2 to 10.6). Patients with lateral ST segment depression (n = 91, 21%) had higher rates of death (14.3% vs. 2.6%, p < 0.001), severe heart failure (14.3% vs. 4.1%, p < 0.001) and angina with electrocardiographic changes (20.0% vs. 11.6%, p = 0.04) than did the remaining patients, even though they had similar peak creatine kinase, MB fraction levels (129 ± 96 vs. 122 ± 92 IU/liter, p = NS). In contrast, ST segment depression not involving the lateral leads did not predict a poor outcome. Among patients who were catheterized, those with lateral ST segment depression had a lower left ventricular ejection fraction (57 ± 12% vs. 66 ± 13%, p = 0.001) and more frequent left main coronary artery or three-vessel disease than did the remaining patients (60% vs. 22%, p < 0.001).

CONCLUSIONS

In patients with a first non–ST segment elevation acute MI, ST segment depression in the lateral leads on hospital admission predicts a poor in-hospital outcome.     

The distinction between coronary and myocardial reperfusion after thrombolytic therapy by clinical markers of reperfusion

Objectives. We sought to examine the hypothesis that rapid resolution of ST-segment elevation in acute myocardial infarction (AMI) patients with early peak creatine kinase (CK) after thrombolytic therapy differentiates among patients with early recanalization between those with and those without adequate tissue (myocardial) reperfusion.Background. Early recanalization of the epicardial infarct-related artery (IRA) during AMI does not ensure adequate reperfusion on the myocardial level. While early peak CK after thrombolysis results from early and abrupt restoration of the coronary flow to the infarcted area, rapid ST-segment resolution, which is another clinical marker of successful reperfusion, reflects changes of the myocardial tissue itself.Methods. We compared the clinical and the angiographic results of 162 AMI patients with early peak CK (≤12 h) after thrombolytic therapy with (group A) and without (group B) concomitant rapid resolution of ST-segment elevation.Results. Patients in groups A and B had similar patency rates of the IRA on angiography (anterior infarction: 93% vs. 93%; inferior infarction: 89% vs. 77%). Nevertheless, group A versus B patients had lower peak CK (anterior infarction: 1,083 ± 585 IU/ml vs. 1,950 ± 1,216, p < 0.01; and inferior infarction: 940 ± 750 IU/ml vs. 1,350 ± 820, p = 0.18) and better left ventricular ejection fraction (anterior infarction: 49 ± 8, vs. 44 ± 8, p < 0.01; inferior infarction: 56 ± 12 vs. 51 ± 10, p = 0.1). In a 2-year follow-up, group A as compared with group B patients had a lower rate of congestive heart failure (1% vs. 13%, p < 0.01) and mortality (2% vs. 13%, p < 0.01).Conclusions. Among patients in whom reperfusion appears to have taken place using an early peak CK as a marker, the coexistence of rapid resolution of ST-segment elevation further differentiates among patients with an opened culprit artery between the ones with and without adequate myocardial reperfusion.     

Characteristics of patients less than 45 years of age compared with older patients undergoing coronary artery bypass grafting

Background: Coronary artery disease (CAD) was not recognized as common among young patients until the study by Yater in 1948. Subsequent studies further elucidated the nature of the disease, which had become more apparent in the younger groups. Hypothesis: The study was undertaken to determine the prevalence of risk factors and severity of coronary disease among young patients aged ≤ 45 years undergoing coronary artery bypass grafting (CABG) compared with older patients. Methods: in all, 112 young patients aged ≥ 45 years (Group 1) and 798 older patients aged > 45 years (Group 2) were analyzed for trends to hypertension, smoking, diabetes, family history of heart disease, hypercholesterolemia, obesity, and history of previous myocardial infarction (MI). The severity of disease was examined in terms of number of diseased vessels, vessel size, number of grafts performed, performance of endarterectomies, and left ventricular function. Results: Group 1 had a higher incidence of positive family history (68.5 vs. 51.2%, p < 0.05), and lower incidences of hypertension (62.7 vs. 81.5%, p < 0.05), obesity (42.9 vs. 83.9%, p<0.05), and history of previous MI (54.5 vs. 94.6%, p < 0.05). Group 2 had a higher incidence of left main disease (22.6 vs. 11.4%, p < 0.05). The distribution of the affected vessels of the young patients was most commonly the left anterior descending (90.4%) followed by the right coronary (79.8%) and circumflex arteries (69.2%). Group 2 had more grafts per patient (3.82 vs. 3.37, p< 0.05). The size of the diseased vessels measured intraoperatively was similar (1.56 vs. 1.58 mm, p = NS) in both groups. Endarterectomy was performed almost three times more often in Group 1 patients (8.2 vs. 3.0%, p>0.05). Operative mortality was less in Group 1 mean (1.8 vs. 6.3%, p < 0.05). Group 2 had a greater mean left ventricular ejection fraction (53.8 vs. 49.7%, p< 0.05). Conclusion: Compared with the older population, patients < 45 years of age who underwent CABG had (1) a higher incidence of positive family history of CAD, (2) a higher likelihood of requiring an endarterectomy, and (3) lower operative mortality rate despite a slightly poorer ventricular function.     

Characteristics, management, and in-hospital mortality of acute myocardial infarction in the "real world" in France--data from a large unselected cohort of 2,519 consecutive patients in a French region

OBJECTIVE: The prospective PRIMA study (Prise en charge de l'Infarctus du Myocarde Aigu; management of acute MI) sought to determine characteristics, management, and in-hospital mortality of myocardial infarction (MI), regardless of age and hospital facilities, in the "real world" in a region in France. METHODS AND RESULTS: Data were prospectively collected in all patients with MI admitted in all hospitals in three departments in the Rh ne-Alpes region between September 1, 1993 and January 31, 1995. 2,519 patients (68% men; mean +/- SD: 68 +/- 14 years) were included. Time from onset of symptoms to admission was < 6 h in 56% of the patients (median: 4 h 30 min). MI was non-Q wave in 12%. Among Q wave MI, location was anterior in 44%. At admission, Killip class was > 1 in 33%. The overall rate of thrombolysis was 36%. It was significantly higher in men than in women, in younger patients than in older patients, in lower Killip classes, in Q wave MI, and when the delay before initial medical intervention was < 6 hours. After age-adjustment, there was no difference between men and women for thrombolysis rate (odds ratio women/men: 0.92; p = 0.10). During the first 5 days, Killip class worsened in 17%. In-hospital mortality rate was 14%. Multivariate analysis identified age, anterior location, presence of Q waves, and higher Killip classes as significant predictors of in-hospital mortality. CONCLUSIONS: This large unselected cohort revealed that among patients with MI in a French region, there was a high proportion of elderly patients, a low rate of thrombolysis, and a high in-hospital mortality.     

Long-term captopril treatment improves diastolic filling more than systolic performance in rats with large myocardial infarction

Objectives. This study sought determine the effects of long-term angiotensin-converting enzyme (ACE) inhibition on left ventricular (LV) diastolic filling in postinfarction heart failure.Background. Long-term treatment with ACE inhibitors is beneficial in experimental animals and patients with heart failure. Because this treatment typically produces only small improvements in LV systolic function, we hypothesized that improvements in LV diastolic filling might contribute to the overall beneficial effects of ACE inhibitors after myocardial infarction (MI).Methods. We performed transthoracic echocardiographic-Doppler examinations in rats 1 and 6 weeks after transmural MI or sham operation. Rats with MI were randomized to no treatment (n = 10) or captopril (2 g/liter in drinking water, n = 8) after the baseline echocardiogram.Results. Six weeks after MI, untreated rats bad significant LV dilation compared with sham-operated rats (LV diastolic dimension [mean ± SEM] 10.7 ± 0.3 vs. 8.5 ± 0.3 mm, p < 0.05). Rats with untreated MI also had impaired fractional shortening (9 ± 1% vs. 34 ± 2%, p < 0.05) and depressed systolic thickening of the noninfarcted posterior wall (37 ± 3% vs. 65 ± 9%, p < 0.05). Rats with MI showed progressively restricted LV diastolic filling as assessed by transmitral Doppler recordings. At 6 weeks, peak early filling velocity (E) was increased (97 ± 3 vs. 77 ± 2 cm/s, p < 0.05), E wave deceleration was more rapid (23 ± 3 vs. 12 ± 1 m/s², p < 0.05), isovolumetric relaxation time was decreased (18 ± 1 vs. 24 ± 1 ms, p < 0.05), and late filling velocity was lower (26 ± 7 vs. 34 ± 1 cm/s, p < 0.05) in rats with MI versus sham-operated rats. Compared with rats with untreated MI, rats receiving captopril had similar LV diastolic dimensions (10.5 ± 0.35 vs. 10.7 ± 0.35 mm), slightly higher fractional shortening (16 ± 2% vs. 9 ± 1%, p < 0.05 [captopril MI vs. untreated MI]) and unchanged posterior wall thickening (49 ± 12% vs. 37 ± 3%, p = 0.3). In contrast, captopril almost completely normalized diastolic filling abnormalities (E velocity 82 ± 5 cm/s, p < 0.05 [captopril MI vs. untreated MI]; E wave deceleration rate 15 ± 2 m/s², p < 0.05 [captopril MI vs. untreated MI]; isovolumetric relaxation time 20 ± 1 ms).Conclusions. Long-term captopril treatment in rats with a large MI modestly limits LV remodeling and the development of systolic dysfunction but markedly improves the restrictive diastolic filling abnormalities that are seen in untreated rats.     

The relationship between the electrocardiographically estimated infarct size and 1- and 2-year survival in acute myocardial infarction

In 587 patients with acute myocardial infarction (AMI) and no previous MI, electrocardiographically estimated infarct size was related to 1- and 2-year mortality. The overall mortality was higher in patients with transmural MI (Q- or R-wave changes in standard ECG) than in patients with subendocardial infarction (ST-T-wave changes in standard ECG) after 1 year (18.8% compared to 6.5% p less than 0.001) and after 2 years (22.2% compared to 13.8%, p = 0.049). When patients who were alive during primary hospitalization were analyzed separately, slightly higher mortality was found in patients with transmural MI than in subendocardial MI after 1 year (9.6% compared to 4.2%, p = 0.076) while no difference was found after 2 years (13.4% as compared to 11.7%, p greater than 0.2). In a subgroup of patients with anterior MI, precordial mapping with 24 chest leads was analyzed 4 days after arrival in hospital (n = 197). Patients were divided into quartiles according to the sum of R waves, the sum of Q waves, and the number of Q waves. There was a similar overall mortality in each quartile after 1 year and after 2 years regardless of ECG parameters studied. Neither did we find any correlation between the sum of R waves in leads II, III, and aVF on the fourth day in patients with inferior MI and overall 1- or 2-year mortality rate, although there was a trend towards higher mortality with more ECG changes.     

Global left ventricular function and regional wall motion in pure mitral stenosis-Left ventricular function in pure mitral stenosis

Global left ventricular function (LVF) and scgmental wall motion of the left ventricle are registered in 113 patients presenting a pure mitral stenosis (MS) and in a control group of 50 individuals. The segmental wall motion is measured on the end-diastolic-end-systolic frames of the left ventricle, obtained from right anterior oblique (RAO) monoplane cineangiography. Measurement of the segmental wall shortening is performed using the Stanford method. Group 1 includes 68 patients (60% of the total number of patients studied). These patients show no pathological contraction abnormality. In this group, the global LVF is not different from the control group. Group 2 includes 45 patients (40% of the total) for whom contraction abnormalities are present: anterior hypokinesis in 20% of the cases (anterior area mean shortening (AAS) = 18±8%; p<0.001 vs. group 1 and control group), and posterior hypokinesis in 20% of the cases (posterior area mean shortening (PAS) = 9.8 ±5.8%, p<0.001 vs. group 1 and control group). In this group, global LVF is impaired; ejection fraction (EF) = 0.57±0.1% (p<0.001 vs. group 1); velocity of circumferential fiber shortening (Vcf) = l±0.3 circ/s (p<0.001 vs. group 1); end-diastolic pressure (EDP) = 11±5 mmHg (p<0.01 vs. group 1). Segmental contraction abnormalities appear to be the main factor involved in the global LVF impairment. Segmental wall motion abnormalities could be related to subvalvular fibrosis, or LV filling difficulties, or principally, to a possible interplay between the right and the left ventricles.     

Mechanism of left a trial enlargement related to ventricular diastolic impairment in hypertension

Background and hypothesis: Systemic hypertension is the leading cause of left ventricular (LV) hypertrophy. The present study aimed to investigate the mechanism of left atrial (LA) enlargement in patients with hypertensive heart disease during cardiac catheterization. Methods: Data were obtained from eight control subjects and seven patients with hypertensive heart disease. Left atrial and LV pressures from catheter-tip micromanometer, and LA and LV volumes from biplane cineangiograms were analyzed during the same cardiac cycle. Results: Left atrial maximal volume were 93 ± 26 ml in patients with hypertensive heart disease and 63 ± 12 ml in control subjects (p<0.05). In patients with hypertensive heart disease, time constant of LV relaxation was significantly greater than that in controls (54 ± 18 vs. 31 ± 16 ms, respectively p<0.01). Left atrial maximal volume correlated with time constant of LV relaxation (r = 0.86, p<0.01). The ratio of LV filling volume before LA contraction to LV stroke volume in patients with hypertensive heart disease was significantly lower than that in control subjects (65 ± 13 vs. 76 ± 7%, respectively p<0.05). On the other hand, the ratio of LV filling volume during LA contraction to stroke volume in patients with hypertensive heart disease was significantly higher than that in controls (35 ± 13 vs. 24± 7%, respectively p<0.05). Left atrial volume before LA contraction in patients with hypertensive heart disease was significantly larger than that in controls (74 ± 22 vs. 47 ± 10 ml, respectively, p<0.01). During LA contraction, LA work was significantly increased in patients with hypertensive heart disease compared with that in controls (274 ± 101 vs. 94 ± 42 mmHg. ml, respectively p<0.001). Left atrial work showed significant correlation with LA volume before LA contraction (r = 0.75, p <0.01). Conclusion: Left ventricular diastolic filling was impaired in patients with hypertensive heart disease. Enlargement of left atrium might be attributed to the impairment of blood flow from left atrium to left ventricle due to the increased LV stiffness.     

Physician electrocardiogram reading in the emergency department—Accuracy and effect on triage decisions

Objective:To determine how well physicians in emergency departments read electrocardiographic (ECG) ST-segment and T-wave changes and how this affects triage decisions. Methods:In the emergency departments of six teaching and nonteaching hospitals, the authors prospectively collected physicians’ ECG readings and clinical data for 2,320 patients presenting with possible acute cardiac ischemia from 1979 to 1981. Results:Compared with electrocardiographers, the study physicians misread as normal41% of abnormal ST segments and 36% of abnormal T waves, and misread as abnormal14% of normal ST segments and 17% of normal T waves. Trainees were significantly more sensitive readers of T-wave changes but less specific readers of both ST-segment and T-wave changes when compared with other physicians. Suboptimal triage was more likely when abnormal ST segments or T waves were misread as normal (22% vs. 11% p<0.01, and 18% vs. 14%, p=0.08, respectively). Conversely, coronary care unit (CCU) admission for patients withoutacute cardiac ischemia was more likely when normal ST segments were misread as abnormal (23% vs. 13%, p<0.0001). Conclusions:Physicians in emergency departments often misread the ST segments and T waves of patients with possible acute cardiac ischemia. Misreading is related to suboptimal triage and unnecessary CCU admission. Training emergency physicians to make these distinctions more accurately could improve medical care and hospital utilization. Received from the Center for Cardiovascular Health Services Research, Divisions of Clinical Decision Making and General Medicine, Department of Medicine, New England Medical Center, Boston, Massachusetts. Supported by Agency for Health Care Policy and Research and Technology Assessment grants R01 HS02068 and R01 HS0554901, and by the National Library of Medicine Medical Information Program training grant LM7044 and research grant LM4493.     

Electrocardiographic prediction of ejection fraction and site of LAD occlusion in anterior myocardial infarction

Q-wave anterior myocardial infarctions due to occlusion of the left anterior descending artery (LAD) are generally associated with the most extensive left ventricular damage. The presence of abnormal Q waves on the electrocardiogram (ECG) provides important information to localize the site of left ventricular infarction. However, the relationship between abnormalities of the QRS morphology in the precordial leads and angiographic information such as ejection fraction and the site of LAD occlusion (before or after the first septal perforator) has not been studied extensively. Seventy-three patients with single-vessel disease with complete LAD occlusion, abnormal QRS morphology in leads V₁-V₄ on ECG, and abnormal wall motion with contrast ventriculography were studied retrospectively. LAD occlusions were proximal to the first septal perforator in 33 patients and distal in 40 patients. Q waves were present in 59 patients, and the other 14 patients had either minimal R waves (<0.25 mm), poor R-wave progression, or R-wave regression. A significantly higher ejection fraction was associated with the presence of R wave in V₂ (0.52 ± 0.18 vs. 0.39 ± 0.15 in the absence of R wave, p<0.003). LAD occlusion after and before the first septal perforator was associated with R wave in V₂ in 67 and 36% of patients, respectively. Sensitivity and specificity of predicting occlusion after the first septal perforator based on R wave in V₂ was 0.68 and 0.64, respectively. In patients with anterior myocardial infarctions, occluded LAD artery, and abnormal QRS morphology in the precordial leads, the presence of R wave in V₂ is a useful predictor of higher ejection fraction. The prediction of site of LAD occlusion in relation to the first septal perforator based on ECG findings is limited and probably not sufficiently specific or sensitive to be of clinical use.     

Magnetocardiographic Assessment of Healed Myocardial Infarction

Background: We evaluated the capability of multichannel magnetocardiography (MCG) to detect healed myocardial infarction (MI). Methods: Multichannel MCG over frontal chest was recorded at rest in 21 patients with healed MI, detected by cine‐ and contrast‐enhanced magnetic resonance imaging, and in 26 healthy controls. Of the 21 MI patients, 11 had non‐Q wave and 10 Q wave MIs. QRS, ST‐segment, T wave and ST‐T wave integrals, ST‐segment and T wave amplitudes, and QRS and ST‐T wave magnetic field map orientations were measured. Results: The MCG repolarization indexes, such as ST segment and ST‐T wave integrals, separated the MI group from the controls (ST‐T wave integral ?1.4 ± 5.3 vs 1.5 ± 4.7 pTs , P = 0.034 ). The abnormalities were more distinct in the Q wave‐MI than in the non‐Q wave MI subgroup. In the latter, however, a trend similar to the Q wave MI group was found. The relation of QRS area to ST segment and T wave integral improved the detection of healed MIs compared to the ST‐T wave indexes alone (QRS‐ST‐T discordance 14 ± 10 vs 5.0 ± 7.1 pTs, P = 0.003 ). When comparing the MI group to the controls, the orientation of the magnetic field maps differed in the ST‐T wave maps (163 ± 119° vs 58 ± 17°, P < 0.001) but not in the QRS maps (111 ± 95° vs 106 ±93°, P = 0.646) . Conclusions: The MCG repolarization variables can detect healed MI. These ST‐T wave abnormalities are more pronounced in patients with Q wave MI than in patients with non‐Q wave MIs. Relating the signals of depolarization and repolarization phases improves the detection of healed MI. Repolarization abnormalities are common in healed MI and thus should not always be interpreted as present ongoing ischemia.