Nontransmural myocardial infarction: A comparison of hospital and late clinical course of patients with that of matched patients with transmural anterior and transmural inferior myocardial infarction

The hospital and long-term course of 67 patients with nontransmural myocardial infarction was compared with that of 66 patients with transmural anterior and 63 patients with transmural inferior infarction matched for age, sex, previous infarction and prior congestive heart failure. During their hospital stay, patients with nontransmural infarction had significantly less congestive heart failure and fewer intraventricular conduction defects than did patients with transmural anterior infarction; fewer atrial tachyarrhythmias and less sinus bradycardia and atrioventricular block than did patients with transmural inferior infarction; and an incidence of hypotension, pericarditis and ventricular irritability similar to that of patients in the other two groups. Patients with nontransmural infarction had a significantly lower coronary care unit mortality rate (9 percent) than that of patients with transmural anterior or transmural inferior infarction (20 and 19 percent, respectively). By 3 months, the mortality rate had risen to 14 percent in patients with nontransmural infarction, but was significantly higher (29 and 27 percent, respectively) in patients with transmural anterior or transmural inferior infarction. Angina was common in all three groups, occurring in more than 50 percent of patients during a mean follow-up period of 28.6 months after hospital discharge.In contrast, the incidence of subsequent myocardial infarction was significantly greater in patients with nontransmural myocardial infarction, occurring in 21 percent at 9 months compared with only 3 percent of patients with transmural anterior (p <0.01) and 2 percent of patients with transmural inferior (p <0.05) infarction. By 54 months, 57 percent of patients with nontransmural infarction had sustained a new infarction contrasted with only 12 percent of patients with transmural anterior (/p <0.001) and 22 percent of patients with transmural inferior (p <0.01) infarction. Late mortality increased in patients with nontransmural myocardial infarction and, although this group had a significantly better survival rate at 3 months, the overall late mortality of the three groups was comparable. The study suggests that nontransmural myocardial infarction is an unstable ischemic event associated with a great risk of later myocardial infarction and high late mortality rate. A more aggressive diagnostic and therapeutic approach may be warranted in patients with nontransmural myocardial infarction.     

A Comparison of Nontransmural and Transmural MyocardiaI Infarction

Summary: A comparison of nontransmural and transmural myocardial infarction. J. Boxall and A. Saltups, Aust. N.Z. J. Med ., 1 980, 10 , pp. 176–179.
This report compares the past history, hospital course and follow-up of 70 patients with nontransmural myocardial infarction compared to 259 patients with transmural myocardial infarction
The pre-infarction history in the two groups is similar with respect to angina and infarction. The hospital course for non-transmural myocardial infarction is not a guide for future cardiac events and the post-hospital prognosis in the two groups is similar. Nontransmural myocardial infarction has a lower hospital mortality ( P <0.05). Patients in whom nontransmural myocardial infarction is a first coronary event have a lower incidence of subsequent angina ( P < 0.05).
The study demonstrates that myocardial infarction without development of q waves does not have an unfavourable long term outlook when compared to transmural infarction. This finding is contrary to reports which suggest a poor prognosis and recommend early coronary anteriography with a view to aorto-coronary bypass in patients with nontransmural infarction     

Coronary angiography and left ventriculography in survivors of transmural and nontransmural myocardial infarction

Recent studies have suggested a similar prognosis for patients with transmural myocardial infarction and nontransmural myocardial infarction despite a smaller infarct size in the latter patients estimated by creatine phosphokinase (CPK). Thirty-one patients with transmural myocardial infarction and 17 patients with nontransmural myocardial infarction as defined by electrocardiographic criteria underwent coronary angiography and left ventriculography from 10 to 24 days after they had an acute myocardial infarction. Forty-three of these 48 patients were asymptomatic following their myocardial infarction. When compared to patients with nontransmural myocardial infarction, those with transmural myocardial infarction had greater peak CPK levels, 1,090 +/- 210 versus 290 +/- 60 IU (p less than 0.01). There was no difference in prevalence of single, double or triple vessel coronary artery disease, mean number of coronary arteries 50 per cent narrowed (2.0 +/- 0.2 versus 2.0 +/- 0.2), near total or total occlusions, coronary score (Friesinger) (7.9 +/- 0.6 versus 8.2 +/- 0.7), left ventricular ejection fraction (48 +/- 2 versus 53 +/- 4), or per cent of akinetic-dyskinetic myocardial segments (66 of 242 [27 per cent] versus 32 of 132 [24 per cent]) between two groups. The similar extent of coronary artery narrowing and degree of left ventricular dysfunction may explain the similar prognosis for patients with transmural myocardial infarction and those with nontransmural myocardial infarction despite differences in enzymatically estimated acute infarct size.     

The short- and long-term prognosis of patients with transmural and nontransmural myocardial infarctio

To compare the long-term prognosis in patients surviving transmural with patients surviving nontransmural myocardial infarctions, the records of 188 consecutive patients with clinical histories and enzyme elevations consistent with acute infarction were reviewed. According to standard electrocardiographic criteria the patients were divided into two groups: 148 with transmural myocardial infarction (group 1) and 40 with nontransmural myocardial infarction (group 2). Of the patients who survived hospitalization, follow-up data were obtained on 119 of 124 patients in group 1 and 36 of 37 patients in group 2 at a mean follow-up period of 36 months. In group 2, the patients had a high incidence of sudden death after discharge (33 per cent in group 2 versus 15 per cent in group 1, p < 0.02) as well as a significantly higher incidence of death from all cardiac causes (41.6 per cent in group 2 versus 24.3 per cent in group 1, p < 0.05). Furthermore, the patients in group 2 still alive at the end of the follow-up period had an increased incidence of angina pectoris and of recurrent infarction. The data suggest that patients with nontransmural myocardial infarction carry a particularly guarded prognosis.     

Clinical characteristics,electrocardiographic and enzyme correlations,and long-term prognosis of patients with chest pain associated with ST depression and/or T wave inversion

The clinical characteristics, electrocardiographic changes, and long-term prognosis were studied in 50 patients suffering nontransmural myocardial infarctions. It is concluded that nontransmural myocardial infarcts tend to occur in older patients with known coronary atherosclerosis and these infarctions are frequently preceded by a period of unstable angina. The clinical course is often complicated with congestive heart failure and other major management problems. Three different groups of electrocardiographic changes were noted and all four in-hospital deaths showed the same pattern of electrocardiographic changes. The prognosis of patients suffering nontransmural myocardial infarctions is not good, as evidenced by a death rate similar to reported patients suffering transmural myocardial infarction and a significant incidence of cardiovascular disability in those who survive.     

Nontransmural versus transmural myocardial infarction: A morphologic study

Although “nontransmural” and “transmural” are morphologic terms used widely to distinguish patients with myocardial infarction, controversy exists as to their meaning regarding clinical course. For this study, a transmural infarct was defined as one that involves essentially the full thickness of the ventricular wall, and nontransmural was defined as something less. The purpose of this study was to identify true morphologic nontransmural acute (less than 21 days old) infarcts at autopsy and compare them with transmural (full-thickness) infarcts in age-matched subjects, for clinical and pathologic similarities and differences. Among the autopsy subjects, comparing 35 nontransmural and 35 transmural infarcts, there was no significant difference with regard to subjects' race or sex, chest pain, arrhythmias, heart block, or cause of death; transmural myocardial infarctions did have a higher frequency of new Q waves (30 of 35 versus six of 35, p < 0.001) and presented more often with increasing dyspnea. At autopsy, there were no significant differences regarding heart weight, location of infarcts, severity of coronary disease, age of acute infarct, or total size of infarct (18 percent of left ventricle for nontransmural versus 22 percent for transmural). There was, however, a significantly greater tendency for those with nontransmural infarct to have evidence of prior infarction at autopsy (27 of 35 versus 19 of 35, p < 0.05). Acute coronary thrombi in the distribution of the infarct were significantly more common among transmural myocardial infarcts (32 of 35 versus 18 of 35, p < 0.001). Morphologically, the nontransmural infarcts showed mural involvement ranging from 20 to 90 percent of the left ventricle, and histologically showed more contraction band (i.e., reflow) injury (57 percent with more than 30 percent contraction band necrosis) compared with transmural infarcts (32 percent with more than 30 percent contraction band necrosis) (p < 0.05). Fatal nontransmural and transmural infarcts have major clinical and pathologic similarities, but differences in number of prior infarcts, type of necrosis, and occurrence of coronary thrombi suggest differing pathophysiology. The heterogeneity of both transmural and nontransmural infarcts likely accounts for existing differences among clinical studies regarding prognosis. Although this classification system has value in the clinical setting, that at times it represents an imprecise oversimplification of infarct type should be recognized in assessing individual patients.     

Doughnut pattern of technetium-99m pyrophosphate myocardial uptake in patients with acute myocardial infarction: a sign of poor long-term prognosis.

Thirty survivors of acute myocardial infarction with 3+ or 4+ positive technetium-99m pyrophosphate myocardial scintigrams were followed up for 28 +/- 3.1 months (mean +/- standard deviation). Three patient groups were identified from the pattern of radioactive uptake in the scintigram: Group I, 16 patients with focal uptake (anterior in 7, lateral in 2, posterior in 3 and inferior in 4); Group II, 6 patients with anterior myocardial infarction and a doughnut pattern of uptake; Group III, 8 patients with nontransmural myocardial infarction and a diffuse pattern of uptake. Late complications developed in all patients with the doughnut pattern of uptake compared with 43 percent of patients with the focal pattern and 12 percent of patients with the diffuse pattern. After discharge from the hospital, five of six patients with a doughnut pattern of uptake died (mean survival time 9.8 months after the initial myocardial infarction). This mortality rate (83 percent) was significantly greater than that of patients with a focal (mortality rate 6 percent) or diffuse (no mortality) pattern of uptake. The doughnut pattern of technetium-99m pyrophosphate myocardial uptake in patients with acute myocardial infarction appears to identify a subgroup of patients with a very poor long-term prognosis.     

Early appearance of MB-creatine kinase activity in nontransmural myocardial infarction detected by a sensitive assay for the isoenzyme

The early release patterns of MB-creatine kinase (CK-MB) in myocardial ischemia and infarction are largely unknown. We utilized a sensitive column Chromatographic assay of CK-MB activity (precision = 1.1 IU/liter) and sequential CK-MB samples were obtained during the first 6 hours of illness to define the early time course of enzyme release. The average CK-MB in 39 normal subjects was 2.4 ± 0.93 (mean ± standard deviation (SD)). Twenty-two patients with ischemic chest pain, in whom myocardial infarction did not develop, were characterized by normal CK-MB's (2.4 ± 1.0). Of 39 patients in whom transmural myocardial infarction developed, 28 (72 percent) were found to have abnormal CK-MB either initially or over a 20-minute sampling period. In contrast, 100 percent of the patients considered to have sustained a nontransmural myocardial infarction had abnormal initial CK-MBs and subsequently demonstrated significant increases in CK-MB from 28 ± 19 initially to 41 ± 30 lU/liter (P < 0.01, N = 16) over the 20-minute sampling period. Thus, CK-MB appears earlier in plasma following nontransmural myocardial infarction than transmural myocardial infarction, probably reflecting perfusion to ischemic myocardium.     

Left ventricular functional alterations at rest and during submaximal exercise in patients with recent myocardial infarction

Submaximal exercise testing with radionuclide ventriculography was performed in 117 patients prior to hospital discharge 16.7 ± 6.7 days (SD) following acute myocardial infarction. The hypothesis tested in this study was that patients with different locations and types of infarction have different functional responses to submaximal exercise prior to discharge. The distribution of the myocardial infarctions were anterior transmural in 33, Inferior transmural in 39, anterior nontransmural in 23, inferior nontransmural in 19, and indeterminant in three. Patients with transmural infarction generally had significantly larger resting left ventricular volumes at enddiastole and end-systole and lower ejection fractions and systolic blood pressure/end-systolic volume Indexes than patients with nontransmural infarctions (p < 0.05). During submaximal exercise, the change in end-systolic volume was significantly different in these two groups. When patients were separated further into anterior and inferior transmural subgroups, the patients with anterior transmural infarction had significantly lower left ventricular ejection fractions and higher right ventricular ejection fractions than the group with inferior transmural Infarction (p < 0.05). In response to exercise, the group with anterior transmural infarction had a significant decrease in left ventricular ejection fraction and a blunted systolic blood pressure/left ventricular end-systolic volume index, in comparison to patients with inferior myocardial infarction (p < 0.05); this was the only group to have a significant increase in end-systolic volume. The group variance for the parameters studied was large, particularly during exercise when the individual responses were frequently directionally opposite from the group means. The group with anterior transmural infarction was the most homogenous, with 26 of 33 having a directionally abnormal response to submaximal exercise. It was concluded that the group with anterior transmural infarction generally displayed the most abnormal left ventricular function. However, despite significant group differences in resting ventricular function with different infarcts, the intragroup variability at rest and in response to exercise was too great to permit an accurate prediction of the subject's resting ventricular performance or to permit a prediction of exercise response based solely on location of the infarct.     

Five-year survival of 728 patients after myocardial infarction. A community study.

This study deals with the five-year survival of 728 myocardial infarction patients who survived the first 28 days after the onset of symptoms. The series was collected by the Helsinki Coronary Register and includes all cases of acute myocardial infarction in the population who were under 66 years of age during the period 1 July 1970 to 30 June 1971. Of the 219 patients who subsequently died, 81.8 per cent died from ischaemic heart disease. The mortality was highest during the first year after the acute phase but did not decrease after the second year. The mortality was higher in patients with a transmural infarction (five-year mortality 34.0%) compared with those with a nontransmural infarction (19.7%). The mortality also was higher for recurrent acute myocardial infractions than for first attacks. The five-year mortality for women was less (20.5%, age-adjusted) than for men (31.6%). This is mainly because of the higher incidence of nontransmural infarcts in women. Acute ischaemic heart disease is more common, more often fatal, and has a poorer long-term prognosis in men than in women in Helsinki. The acute mortality from acute ischaemic heart disease is high in Helsinki when compared with other WHO registers and, in addition, the long-term prognosis seems to be relatively poor in Helsinki.     

Surgical intervention in acute myocardial infarction

The goal of surgical reperfusion during the first hours of acute evolving myocardial infarction is to limit the extent of the infarction. This should be reflected by improved ventricular function and low mortality. Over the past 10 years, 440 patients with transmural myocardial infarction and 261 patients with nontransmural myocardial infarction underwent coronary artery bypass graft surgery within 24 hours of peak symptoms. The in-hospital mortality was 5.2% in the transmural group and 3% in the non-transmural group. In a 10-year study period, the mortality in the transmural group rose to 12.5%, while the mortality in the nontransmural group, followed for an 8-year period, rose to a total of 6.5%. The transmural myocardial infarctions in patients revascularized within 6 hours, showed a significantly improved in-hospital mortality of 3.8% compared to an in-hospital mortality of 12% for reperfusion after 6 hours. Anterior transmural areas of myocardial infarctions were reperfused within 6 hours of symptom onset, and demonstrated improved global ejection fraction and regional wall motion. Little improvement was seen if revascularization was instituted later than 6 hours from symptoms except in patients with adequate collateral perfusion of non-total left anterior descending coronary occlusion. Long-term follow-up of patients revascularized for acute myocardial infarction shows a low rate of subsequent reinfarction, incapacitating angina and sudden death. Left ventricular function at the time of cardiac catheterization correlates well with subsequent long-term mortality.     

Comparison of the influence of acute transmural and nontransmural myocardial infarction on ventricular function

In order to assess the relative impact on left and right ventricular function of nontransmural and transmural acute myocardial infarction (AMI), we performed radionuclide ventriculography in 86 patients (54 men and 32 women) within 16 hours after a first infarct. Nontransmural infarction was present in 19 patients (11 anterior and 8 inferior). Transmural infarction was found in 67 patients (30 anterior and 37 inferior). Left ventricular ejection fractions were higher (0.57 +/- .014 vs 0.46 +/- 0.14, p less than 0.005) and left ventricular end-systolic volume lower (29 +/- 11 vs 42 +/- 20 ml/m2, p = 0.013) in patients with nontransmural infarction compared to those with transmural infarction. Right ventricular ejection fraction also may have been different in the two groups (0.63 +/- 0.15 vs 0.55 +/- 0.13, p = 0.057). In patients with inferior infarction, left and right ventricular ejection fractions were similar in patients with nontransmural and transmural infarction (0.60 +/- 0.09 vs 0.55 +/- 0.10, p = 0.119 and 0.58 +/- 0.14 vs 0.51 +/- 12, p = 0.226). On the other hand, patients with anterior transmural infarction had lower left ventricular ejection fractions (0.36 +/- 0.12 vs 0.54 +/- 0.17, p = 0.003) but similar right ventricular ejection fractions (0.60 +/- 0.13 vs 0.66 +/- 0.14, p = 0.14) compared to those with nontransmural anterior infarction. In 29 additional patients with a history of previous infarction, no differences in any of the parameters studied were found between those with transmural and those with nontransmural infarcts.(ABSTRACT TRUNCATED AT 250 WORDS)     

Indirect assessment of left ventricular performance in acute myocardial infarction

One hundred patients admitted to a cardiac care unit had indirect serial determinations of left ventricular systolic ejection times. Patients were divided into groups with transmural infarction, nontransmural infarction, and no infarction, according to clinical, biochemical, and electrocardiographic criteria. Total electromechanical systole and left ventricular ejection time were shortened in acute myocardial infarction, whereas the pre-ejection period and its components, the Q-S1 and isovolumic contraction time intervals, were prolonged. The most abnormal measurements were observed in patients with transmural infarction. Patients with nontransmural infarction demonstrated less severe abnormalities of the systolic ejection times, and the patients without infarction were the least affected. Some of the greatest deviations in the measured intervals were observed in the transmural infarction patients who died. Indirect measurement of left ventricular systolic ejection time is a valuable adjunct in the bedside assessment of left ventricular performance and provides a prognostic index for patients with acute myocardial infarction.     

Time-related changes in the Q-T interval in acute myocardial infarction: possible relation to local hypocalcemia

In 63 patients with either acute transmural or nontransmural myocardial infarction, the Q-T interval was prolonged beyond normal limits on at least 1 of the 5 days after infarction in 27 patients (8 with transmural and 19 with nontransmural infarction). The time-related changes in the corrected Q-T (Q-Tc) interval were defined for the entire sample and showed significant expansion, maximal on day 2, from a preinfarction control value. By day 5, the Q-Tc interval was no longer significantly prolonged and was not expanded beyond normal limits in any patient. Various possible causes of Q-T prolongation in myocardial infarction are local hypothermia, local conduction delay, neurogenic effect and local hypocalcemia. Collateral evidence suggests that the letter may contribute significantly to prolongation.     

Pathologic implications of restored positive T waves and persistent negative T waves after Q wave myocardial infarction

Objectives. We sought to study the pathologic implications of restored positive T waves and persistent negative T waves in the chronic stage of Q wave myocardial infarction.Background. Some inverted T waves (coronary T waves) become positive after acute myocardial infarction: others retain their negative T wave component for a long time. The pathologic implications of the difference between restored positive T waves and persistent negative T waves in leads with Q waves has not, until now, been given much careful study.Methods. Of 17 patients with anterior or anteroseptal myocardial infarction confirmed by autopsy, 8 (group P) had positive and 9 (group N) had negative T waves in precordial leads with Q waves ≥ 1 year after the onset of myocardial infarction. The appearance and extent of the infarct area and the degree of coronary artery stenosis were evaluated in both groups.Results. At autopsy, seven of eight patients in group P had nontransmural fibrotic changes in the anteroseptal or anterior wall. However, seven of nine patients in group N had a transmural myocardial infarction consisting of only a thin fibrotic layer in the anteroseptal or anterior wall. The left anterior descending coronary artery showed 75% stenosis in 1 patient in each group but >90% stenosis in the remaining 15 patients.Conclusions. Persistent negative T waves in leads with Q waves in the chronic stage of myocardial infarction indicate the presence of a transmural infarction with a thin fibrotic layer, whereas positive T waves indicate a nontransmural infarct containing viable myocardium within the layer.     

Effect of transmural versus nontransmural myocardial infarction on inducibility of ventricular arrhythmias during sympathetic stimulation in dogs

Transmural myocardial infarction interrupts sympathetic nerves and denervates viable muscle distal to myocardial infarction. The effect of sympathetic stimulation on responses to programmed ventricular stimulation was studied in dogs without myocardial infarction (Group I: n = 5), with transmural anterior wall myocardial infarction (Group II: n = 6) and with nontransmural anterior wall myocardial infarction (Group III: n = 9). Ventricular effective refractory period during sympathetic stimulation decreased by 16 +/- 18, 1 +/- 2 and 12 +/- 8 ms (mean +/- SD) in viable muscle of the inferoapical left ventricle in Groups I, II and III, respectively, suggesting efferent sympathetic denervation by transmural myocardial infarction only. Sustained ventricular tachycardia or fibrillation was induced more easily during sympathetic stimulation in six of the six dogs with transmural infarction, but in only two of the nine dogs with nontransmural infarction (p less than 0.01). It is concluded that the partial sympathetic denervation produced by transmural myocardial infarction enhances the ease of induction of ventricular tachycardia and fibrillation during sympathetic stimulation. A similar mechanism may lead to increased risk for lethal arrhythmias during periods of high sympathetic tone in patients with transmural myocardial infarction.     

The prognosis of anterior myocardial infarction revisited: a community-wide study

A study was carried out in metropolitan Baltimore in which the short- and long-term prognosis of 655 patients with anterior myocardial infarction (MI) was compared with that of 520 patients with inferior/posterior MI. The study was performed on a community-wide basis in two time periods before the clinical introduction and widespread use of beta-blockade therapy. After simultaneous adjustment for several socio-demographic and clinical variables, the in-hospital case fatality rate was greater for patients with anterior (27.5%) than for those with inferior/posterior MI (22.9%) (p less than 0.05). Similarly, for those discharged alive from the hospital and followed up for as long as 10 years, patients with infarction of the anterior wall had a significantly poorer long-term survival than that of patients with infarction of the inferior/posterior wall (p less than 0.05). These results suggest that closer surveillance should be directed at patients with anterior myocardial infarction, both during the acute phase and after hospital discharge.     

New approach to interpretation of technetium-99m pyrophosphate scintigraphy in detection of acute myocardial infarction: clinical assessment of diagnostic accuracy.

A modified classification for interpreting technetium-99m pyrophosphate scintigrams defines the 2+ diffuse pattern of tracer uptake as equlvocal rather than positive for acute myocardial infarction. Results of scintigraphy using this classification were compared with results of standard diagnostic tests for myocardial infarction in 235 patients admitted to a coronary care unit with acute chest pain. Of 81 patients with acute transmural infarction by standard clinical, electrocardiographic and serum enzyme criteria, 76 had a positive, 5 an equivocal and none a negative scintigram. Of 18 with acute nontransmural infarction by standard criteria, 7 had a positive, 9 an equivocal and 2 a negative scintigram. This it was uncommon for a patient with acute myocardial infarction, transmural or nontransmural, to have a definitely negative technetium-99m pyrophosphate study. Ten patients had equivocal evidence of infarction by standard criteria. Of the remaining 126 patients with no evidence of acute myocardial infarction by standard criteria, 87 had a negative, 35 an equivocal and 4 a definitely positive scintigram. Thus the definitely positive scintigraphic pattern was relatively highly specific for acute myocardial infarction. If the 2+ pattern had been considered positive, the specificity of the technique would have been greatly decreased. Computer processing strengthened observer certainty of the visual impression but changed the scintigraphic evaluation in only eight cases. Thus, use of an equivocal pattern renders technetium-99m pyrophosphate imaging both an extremely sensitive and specific method for detecting acute myocardial infarction.     

Detection of acute myocardial infarction by technetium-99m polyphosphate

Experimental work has shown that technetium-99m (^99mTc) pyrophosphate accumulates in recently infarcted myocardium and can be detected by external imaging techniques. Twenty-two ^99mTc polyphosphate myocardial studies were performed in 17 patients (in 3 after cardiac surgery) 3 to 20 days after myocardial infarction. Seventeen myocardial studies were performed in 17 control patients (in 6 after cardiac surgery). Twenty millicuries of ^99mTc polyphosphate was injected intravenously 60 to 120 minutes prior to gamma camera imaging in several views. Myocardial images were processed by the Gamma-11 computer system using standardized background subtraction and contrast enhancement. Results of 16 myocardial studies performed 4 to 20 days after transmural myocardial infarction in 12 patients were positive in 13 instances and questionable in 1. The location of the myocardial infarction by imaging corresponded to location by standard electrocardiographic criteria in 8 of the 10 patients with positive findings. In five patients with nontransmural myocardial infarction, results of myocardial imaging were positive in two, questionable in one and normal in one. In one patient with questionable findings results were normal when imaging was repeated 16 days after nontransmural myocardial infarction. Results of 17 control myocardial imaging studies were normal in 16 and questionable in 1. Therefore, ^99mTc polyphosphate myocardial imaging appears promising in the detection and location of transmural myocardial infarction. Its accuracy in detecting nontransmural myocardial infarction may be increased with greater experience and development of sophisticated digital analysis techniques. The method may prove useful in clinical situations such as cardiac surgery in which standard diagnostic aids are difficult to interpret.     

Thallium-201 versus technetium-99m pyrophosphate myocardial imaging in detection and evaluation of patients with acute myocardial infarction

Thallium-201 myocardial imaging is of value in the early detection and evaluation of patients with suspected acute infarction. The extent of a thallium defect in an initial myocardial image may have important prognostic value. Tomographic imaging techniques hold promise for increased diagnostic sensitivity and more accurate quantitation of both infarcted and residual viable myocardium. Thallium imaging may have a special value in characterizing patients with cardiogenic shock and in detecting patients at risk for subsequent infarction or death or both, before hospital discharge.

Approximately 95 percent of patients with transmural or nontransmural myocardial infarction can be detected with technetium-99m pyrophos-phate myocardial imaging if the imaging is performed 24 to 72 hours after the onset of symptoms. Pyrophosphate imaging has been useful in localizing the site and determining the extent of acute myocardial infarction. The “doughnut” pattern is associated with a relatively large incidence of subsequent congestive heart failure and death. However, the clinical utility of this information is limited because it is usually not available when it is most needed, on admission to the coronary care unit. Pyrophosphate imaging may have an important role in the evaluation of patients during the early follow-up period after hospital discharge from an episode of acute infarction. The finding of a persistently positive pyrophosphate image suggests a poor prognosis and is associated with a relatively large incidence of subsequent myocardial infarction and death.