Cocaine-associated chest pain

STUDY OBJECTIVES: To describe the clinical and ECG features of cocaine abusers evaluated in the emergency department and admitted to the medical coronary care unit with chest pain consistent with myocardial ischemia. DESIGN: A four-month retrospective review of all cocaine abusers who presented to the ED with chest pain and a diagnosis of possible myocardial infarction. SETTING: Urban county hospital. TYPE OF PARTICIPANTS: Forty-eight adult cocaine abusers admitted with chest pain. MEASUREMENTS AND MAIN RESULTS: Patients included 34 men and 14 women with a mean age of 29 +/- 7.3 years. The average duration of cocaine abuse in 28 patients for whom it was reported was 5 +/- 4.8 years. Chest pain occurred within one hour of cocaine abuse in 13 admissions (27%), more than one hour after abuse in 13 admissions (27%), and it was not recorded in 23 admissions (47%). Initial ECGs were evaluated in all patients and revealed significant repolarization abnormalities consisting of abnormal ST segment elevations in 18 (37%) and T-wave inversions in 20 (41%) that often persisted on subsequent ECGs. Three patients sustained acute myocardial infarctions. CONCLUSIONS: Our findings confirm a small but significant incidence of myocardial infarction in cocaine abusers presenting to the ED with chest pain. The chronicity of cocaine abuse, the persistence of ECG abnormalities, and the variable temporal relationship of chest pain to cocaine abuse suggest possible chronic myocardial changes as etiologies of ischemia.     

An evaluation of cocaine-induced chest pain

STUDY OBJECTIVE: To determine if enzymatic evidence of acute myocardial injury is present in patients complaining of chest pain after cocaine use when the ECG is normal or nondiagnostic. DESIGN: Serial ECG and creatinine kinase (CK) and CK isoenzymes (CK-ISO) determinations were performed at time of emergency department presentation and every six hours over 12 hours on individuals complaining of chest pain within six hours of last cocaine use. SETTING: ED of an urban tertiary care center. TYPE OF PARTICIPANTS: Forty-two individuals with a mean age of 28.5 years. INTERVENTIONS: Patients with positive CK-ISOs were admitted immediately to formally rule out myocardial infarction. Patients developing ECG changes during observation period also were admitted even if CK-ISOs were normal. Patients with unchanged ECGs and normal CK-ISOs were discharged after 12 hours of observation. RESULTS: Eight patients (19%) had elevated CK and CK-ISO values at presentation. Two of these patients had elevated values on three sequential determinations and were believed to have sustained acute myocardial infarction. Six patients had elevated CK and CK-ISOs at presentation only. ECGs remained normal or nondiagnostic in all patients. CONCLUSIONS: Enzymatic evidence of acute myocardial injury may occur in patients who develop chest pain after cocaine use and have normal or nondiagnostic ECGs. This injury may reflect acute infarction or transient ischemia. Single or serial normal or nondiagnostic ECGs do not rule out ischemia or injury in this group of patients.     

Use of radionuclide imaging in acute coronary syndromes

The triage of patients presenting to the emergency department (ED) with acute chest pain is a diagnostic challenge. Radionuclide myocardial perfusion imaging has been shown to have favorable diagnostic and prognostic value in this setting, with an excellent early sensitivity to detect acute myocardial infarction (MI) not achieved by other testing modalities. A normal resting perfusion imaging study has been shown to have a negative predictive value of over 99% to exclude MI. Observational and randomized trials of both rest and stress imaging in the ED evaluation of patients with chest pain have demonstrated reductions in unnecessary hospitalizations and cost savings compared with routine care. Perfusion imaging has also been used in risk stratification after MI, and for measurement of infarct size to evaluate reperfusion therapies. Novel "hot spot" imaging radiopharmaceuticals that visualize infarction or ischemia are currently undergoing evaluation and hold promise for future imaging of acute coronary syndromes.     

Risk stratification according to the initial electrocardiogram in patients with suspected acute myocardial infarction

Previously developed initial electrocardiogram (ECG) prediction rules were modified to stratify 426 patients with suspected acute myocardial infarction into low-, intermediate-, and high-risk groups (normal, abnormal, and positive ECG categories) for development of acute myocardial infarction and complications of coronary ischemia. Compared with patients with normal ECGs, patients with positive ECGs had a 2.9 times greater risk of interventions, a greater risk of life-threatening complications, and a 14.2 times greater risk of acute myocardial infarction. Compared with patients with abnormal ECGs, patients with positive ECGs had a 1.7 times greater risk of interventions, a 2.6 times greater risk of life-threatening complications, and a 4.9 times greater risk of acute myocardial infarction. This prediction scheme was further improved by assigning "high" risk to any patient requiring an acute intervention during the initial evaluation in the emergency department. Otherwise, risk was assigned according to the ECG category, with normal, abnormal, and positive ECGs corresponding to "low," "intermediate," and high risk, respectively. Hospitals with limited intensive care beds may be able to use these prediction rules as an aid in determining in-hospital disposition of patients with suspected acute myocardial infarction.     

Incidence and predictors of myocardial infarction among patients with atrial fibrillation

OBJECTIVES: We sought to evaluate the utility of excluding myocardial infarction (MI) in patients presenting to the emergency department (ED) with atrial fibrillation (AF) and to identify predictors of MI in this group. BACKGROUND: Patients with AF are frequently admitted to the hospital, in part, to exclude an associated MI. There are no prospective data on unselected patients to support this common practice. METHODS: We conducted a prospective cohort study of all patients who presented to a single-center ED with the primary diagnosis of AF. RESULTS: Of a total of 255 patients, 190 (75%) were admitted to the hospital, and 109 of them underwent a standard "rule-out MI" protocol. Of these 109 patients, six (5.5%) were identified as having an acute MI at the time of admission. Chest pain was present in 39% of patients, with a sensitivity and specificity for the occurrence of MI of 100% and 65%, respectively. ST segment elevation or depression was present in 43% of patients, with a sensitivity and specificity of 100% and 51%. The presence of either major ST segment depression (>2 mm) or elevation on the admission electrocardiogram (ECG) was present in 6%, with a sensitivity of 100% and a specificity of 99%. The resulting positive and negative predictive values were 86% (95% confidence interval [CI] 42% to 99%) and 100% (95% CI 96% to 100%), respectively. Use of this criterion would have reduced the number of rule-out MIs in our study group by 94%, with no loss of sensitivity. CONCLUSIONS: Chest pain and ST segment depression are extremely common findings in patients presenting to the ED with AF and have limited power to predict MI. In contrast, ECG evidence of ST segment elevation or depression >2 mm appears to be a reliable discriminator of which patients are at risk for MI. Patients without significant ST segment changes are at very low risk for MI and may not require performance of the rule-out MI protocol or hospital admission if clinically stable.     

Relationship of exercise or pacing induced ST segment depression and myocardial lactate metabolism in patients with hypertrophic cardiomyopathy

To elucidate a mechanism and clinical implications of chest pain and ST segment depression during exercise in patients with hypertrophic cardiomyopathy (HCM), we investigated myocardial lactate metabolism during atrial pacing in 18 patients with HCM and 7 control subjects with normal coronary arteriograms. At an average peak pacing rate of 146 beats/min, 11 patients with HCM showed the lactate extraction ratio decreasing to less than 5%, and 6 of them produced lactate, suggesting the development of myocardial ischemia. These 11 patients with abnormal lactate metabolism demonstrated ST segment depression (82%) and chest pain (73%) during pacing and also presented abnormal results (55%) on an exercise stress test. These abnormal findings were not observed in the other 7 patients who had ratios of 5% or more at peak pacing. These observations suggest that ST segment depression and chest pain are manifestations of myocardial ischemia even in patients with HCM who have normal coronary arteriograms, and that patients with pacing induced abnormal lactate metabolism are at an increased risk of developing myocardial ischemia during exercise.     

Clinical Value of Acute Rest Technetium-99m Tetrofosmin Tomographic Myocardial Perfusion Imaging in Patients With Acute Chest Pain and Nondiagnostic Electrocardiograms

Objectives. We sought to evaluate the clinical use and cost-analysis of acute rest technetium-99m (Tc-99m) tetrofosmin single-photon emission computed tomographic (SPECT) myocardial perfusion imaging in patients with chest pain and a normal electrocardiogram (ECG).Background. Current approaches used in emergency departments (EDs) for treating patients presenting with chest pain and a nondiagnostic ECG result in poor resource utilization.Methods. Three hundred fifty-seven patients presenting to six centers with symptoms suggestive of myocardial ischemia and a nondiagnostic ECG underwent Tc-99m tetrofosmin SPECT during or within 6 h of symptoms. Follow-up evaluation was performed during the hospital period and 30 days after discharge. All entry ECGs, SPECT images and cardiac events were reviewed in blinded manner and were not available to the admitting physicians.Results. By consensus interpretation, 204 images (57%) were normal, and 153 were abnormal (43%). Of 20 patients (6%) with an acute myocardial infarction (MI) during the hospital period, 18 had abnormal images (sensitivity 90%), whereas only 2 had normal images (negative predictive value 99%). Multiple logistic regression analysis demonstrated abnormal SPECT imaging to be the best predictor of MI and significantly better than clinical data. Using a normal SPECT image as a criterion not to admit patients would result in a 57% reduction in hospital admissions, with a mean cost savings per patient of $4,258.Conclusions. Abnormal rest Tc-99m tetrofosmin SPECT imaging accurately predicts acute MI in patients with symptoms and a nondiagnostic ECG, whereas a normal study is associated with a very low cardiac event rate. The use of acute rest SPECT imaging in the ED can substantially and safely reduce the number of unnecessary hospital admissions.     

Right precordial and posterior electrocardiographic leads do not increase detection of ischemia in low-risk patients presenting with chest pain

BACKGROUND: A number of innovative approaches have been investigated for their value in the early detection of acute ischemia or infarction in patients presenting to the emergency department (ED) with chest pain suggestive of a cardiac origin. Prior investigations have demonstrated the utility of adding right precordial and posterior chest leads to the standard 12-lead electrocardiogram (ECG) for identifying right ventricular and posterior wall infarctions in the ED. HYPOTHESIS: To assess the utility of additional ECG leads in low-risk patients presenting to the ED with symptoms suggestive of acute coronary syndromes who are managed in a chest pain evaluation unit (CPEU). METHODS: We studied low-risk patients who presented to the ED with chest pain compatible with myocardial ischemia. Low-risk patients were identified by a normal 12-lead ECG, no arrhythmias or hemodynamic instability, and one negative serum cardiac troponin I. Patients were admitted to the CPEU where a 16-lead ECG was recorded by the addition of 2 right-sided precordial leads (V4R, V5R) and 2 posterior leads (V8, V9) to the standard 12-lead ECG. RESULTS: The 16-lead ECG system was applied to 316 consecutive patients. The study group was a middle-aged population with equal numbers of men and women and an average of 2 cardiac risk factors per patient. The 16-lead ECG demonstrated evidence of myocardial injury in only 1 patient and no evidence of ischemia in any of the 316 patients. CONCLUSION: In patients presenting to the ED with chest pain and evidence of low clinical risk by our criteria, the addition of both right-sided precordial and posterior chest leads to the standard 12-lead ECG did not provide additional information for risk stratification.     

Value of definitive diagnostic testing in the evaluation of patients presenting to the emergency department with chest pain

The optimal diagnostic evaluation of patients presenting to the emergency department (ED) with chest pain but without myocardial infarction or unstable angina is controversial. We performed a prospective, nonrandomized, observational study of 1,195 consecutive patients presenting to the ED with chest pain but who had normal or nondiagnostic electrocardiograms and negative cardiac biomarkers. Patients (mean ± SD age 61 ± 15 years; 55% women) were admitted to the hospital and a standard protocol for evaluation and treatment was suggested. The use of stress myocardial perfusion imaging (MPI) or cardiac catheterization during their index hospitalization, and the 3-month incidence of coronary angiography, percutaneous cardiac intervention, coronary artery bypass surgery, re-presentation to our institution’s ED for chest pain, myocardial infarction, or death were followed. Five hundred nine of 1,195 patients (43%) underwent provocative stress MPI during their index hospitalization; 37% had perfusion defects (predominantly ischemia). Fifty-six of 1,195 patients (4%) underwent cardiac catheterization without stress MPI for their primary diagnostic evaluation. Six hundred thirty of 1,195 patients (53%) had neither MPI or cardiac catheterization during their index hospitalization. During the 3-month follow-up period, patients with a normal stress perfusion study during their index hospitalization had fewer return visits (4%) compared with patients with abnormal perfusion studies (19%), those who underwent catheterization directly (16%), or patients with no initial diagnostic evaluation (15%) (p <0.001). In addition, patients who had a diagnostic evaluation during their index hospitalization had a lower incidence of either acute myocardial infarction (0.9% vs 2.1%) or death (0.4% vs 3.0%, p <0.001) in the 3-month follow-up period. Accordingly, we strongly advocate provocative stress MPI early after presentation for chest pain in all patients with risk factors for coronary artery disease.     

The diagnostic impact of prehospital 12-lead electrocardiography

STUDY HYPOTHESIS: It is feasible to apply prehospital 12-lead electrocardiography to most stable prehospital chest pain patients. Prehospital diagnostic accuracy is improved compared with single-lead telemetry. POPULATION: One-hundred sixty-six stable adult patients who sought paramedic evaluation for a chief complaint of nontraumatic chest pain. METHODS: One-hundred fifty-one prehospital 12-lead ECGs of diagnostic quality were obtained by paramedics on 166 adult patients presenting with nontraumatic chest pain. Paramedics and base station physicians were blinded to the information on acquired prehospital 12-lead ECGs and treated patients according to current standard of care-clinical diagnosis and single-lead telemetry. Final hospital diagnoses were classified into three groups: acute myocardial infarction (24); suspected angina or ischemia (61); and nonischemic chest pain (66). Paramedics and base station physicians' clinical diagnoses and prehospital and emergency department ECGs were similarly classified and compared. Prehospital and ED 12-lead ECGs were read retrospectively by two cardiologists. RESULTS: Paramedics achieved a high success rate (98.7%) in obtaining diagnostic quality prehospital 12-lead ECGs in 94.6% of eligible prehospital patients. For patients with acute myocardial infarction, prehospital ECG alone had significantly higher specificity than did the paramedic clinical diagnosis (99.2% vs 70.9%; P less than .001), and significantly higher positive predictive value (92.9% vs 32.7%; P less than .001). For patients with angina, combining the paramedic clinical diagnosis and the prehospital ECG significantly improved sensitivity (90.2% vs 62.3%; P less than .001) and increased negative predictive value (88.9% vs 71.3%; P less than .02) compared with paramedic clinical diagnosis alone. There was a high concordance between prehospital and ED ECG diagnosis (99.3% for acute myocardial infarction and 92.8% for angina). Furthermore, ten patients whose prehospital ECGs demonstrated ischemia and who had final hospital diagnoses of angina or acute myocardial infarction were mistriaged by paramedics and/or received no base station physician-directed therapy. CONCLUSION: It is feasible to apply prehospital 12-lead electrocardiography to most stable prehospital chest pain patients. Prehospital 12-lead ECGs have the potential to significantly increase the diagnostic accuracy in chest pain patients, approach congruity with ED 12-lead ECG diagnoses, and may allow for consideration of altering and improving prehospital and hospital-based management in this patient population.     

Acute myocardial infarction in chest pain patients with nondiagnostic ECGs: serial CK-MB sampling in the emergency department. The Emergency Medicine Cardiac Research Group.

STUDY OBJECTIVES: This study tested the hypothesis that serial creatine phosphokinase (CK)-MB sampling in the emergency department can identify acute myocardial infarction (AMI) in patients presenting to the ED with chest pain and nondiagnostic ECGs. DESIGN: Patients more than 30 years old who were evaluated initially in the ED and hospitalized for chest pain were studied. Serial CK-MB levels were analyzed prospectively using a rapid serum immunochemical assay for identification of AMI patients in the ED. Presenting ECGs showing new, greater than 1-mm ST elevation in two or more contiguous leads were considered diagnostic for AMI. All other ECGs were considered nondiagnostic ECGs. CK-MB levels were determined at ED presentation and hourly for three hours (total of four levels). Patients with at least one level of more than 7 ng/mL were considered to have a positive enzyme study. The in-hospital diagnosis of AMI was determined by the development of typical serial ECG changes or separate standard cardiac enzyme changes after admission. SETTING: Eight tertiary-care medical center hospitals. METHODS AND MAIN RESULTS: Of the 616 study patients, 108 (17.5%) were diagnosed in the hospital as AMI; 69 of these AMI patients (63.9%) had nondiagnostic ECGs in the ED. Of the patients with nondiagnostic ECGs, 55 (sensitivity, 79.7%) had a positive ED serial CK-MB enzyme study within three hours after presentation. Combining serial ED CK-MB assay results with diagnostic ECGs yielded an 88.4% sensitivity for AMI detection within three hours of ED presentation. The predictive value of a negative serial ED enzyme study for no AMI was 96.2% (specificity, 93.7%). CONCLUSION: Serial CK-MB determination in the ED can help identify AMI patients with initial nondiagnostic ECGs. Use of serial CK-MB analysis may facilitate optimal in-hospital disposition and help guide therapeutic interventions in patients with suspected AMI despite a nondiagnostic ECG.     

Acute myocardial infarction in hemoglobin SC disease

Although there are reports of myocardial infarction (MI) in patients with sickle cell diseases, an antemortem diagnosis of acute MI in a patient with compound heterozygous hemoglobin SC disease has not been reported. Herein, we present a patient with hemoglobin SC who suffered an acute MI. She had typical chest pain for myocardial ischemia, associated with ST elevations on the electrocardiogram (EKG) and elevations of cardiac injury markers diagnostic of infarction. The patient was treated with conventional therapies for acute coronary syndrome and also emergent red blood cell exchange. Interestingly, coronary angiography was completely normal in this patient. Potential mechanisms and management for acute MI in patients with sickle cell disease are discussed.     

Utility of the prehospital electrocardiogram in diagnosing acute coronary syndromes: the Myocardial Infarction Triage and Intervention (MITI) project

Objectives. We sought to determine whether the prehospital electrocardiogram (ECG) improves the diagnosis of an acute coronary syndrome.Background. The ECG is the most widely used screening test for evaluating patients with chest pain.Methods. Prehospital and in-hospital ECGs were obtained in 3,027 consecutive patients with symptoms of suspected acute myocardial infarction, 362 of whom were randomized to prehospital versus hospital thrombolysis and 2,665 of whom did not participate in the randomized trial. Prehospital and hospital records were abstracted for clinical characteristics and diagnostic outcome.Results. ST segment and T and Q wave abnormalities suggestive of myocardial ischemia or infarction were more common on both the prehospital and hospital ECGs of patients with as compared with those without acute coronary syndromes (p ≤ 0.00001). Those with prehospital thrombolysis were more likely to show resolution of ST segment elevation by the time of hospital admission (14% vs. 5% in patients treated in the hospital, p = 0.004). In patients not considered for prehospital thrombolysis, both persistent and transient ST segment and T or Q wave abnormalities discriminated those with from those without acute coronary ischemia or infarction. Compared with ST segment elevation on a single ECG, added consideration of dynamic changes in ST segment elevation between serial ECGs improved the sensitivity for an acute coronary syndrome from 34% to 46% and reduced specificity from 96% to 93% (both p < 0.00004). Overall, compared with abnormalities observed on a single ECG, consideration of serial evolution in ST segment, T or Q wave or left bundle branch block (LBBB) abnormalities between the prehospital and initial hospital ECG improved the diagnostic sensitivity for an acute coronary syndrome from 80% to 87%, with a fall in specificity from 60% to 50% (both p < 0.000006).Conclusions. ECG abnormalities are an early manifestation of acute coronary syndromes and can be identified by the prehospital ECG. Compared with a single ECG, the additional effect of evolving ST segment, T or Q waves or LBBB between serially obtained prehospital and hospital ECGs enhanced the diagnosis of acute coronary syndromes, but with a fall in specificity.     

Increased diastolic blood pressure response to exercise testing when coronary artery disease is suspected. An indication of severity.

One hundred and two consecutive patients with a history of chest pain or recent previous myocardial infarction underwent maximal treadmill stress testing and coronary angiography. The diastolic blood pressure response to exercise was evaluated independently of ST segment change and systolic blood pressure. In the presence of a normal systolic blood pressure response an increase in diastolic blood pressure of 15 mm Hg on at least two determinations during the same stage of exercise was considered abnormal. In 99 patients an accurate diastolic reading was possible. Of these, 61 had a normal diastolic blood pressure response; in 25 of these the ST segment was ischaemic and seven had three vessel coronary artery disease. Thirty eight patients had an abnormal diastolic blood pressure response and 27 of these had an ischaemic ST response. Of the 11 with a negative ST response for ischaemia one had left main stem disease, seven three vessel disease, and three two vessel disease. Patients with an abnormal diastolic response had greater ST depression with more angina at a reduced workload than those with a normal diastolic response. In patients with chest pain an abnormal increase in diastolic blood pressure on exercise reflects severe coronary artery disease. Although no false positives occurred in this study there was an appreciable number of false negatives (sensitivity 46%) in both patients with chest pain and those with infarction. An abnormal diastolic response therefore represents a useful additional diagnostic indicator of coronary artery disease when the ST segment response is normal or borderline. When the diastolic pressure becomes increased with or without ST changes the likelihood of severe coronary artery disease is increased.     

Changes occurring in the postinfarction ECG in relation to age, sex, and previous myocardial infarction

Minnesota codes (MC), expressing Q-QS, ST segment, and T wave abnormalities in ECGs taken during the acute event and at a 1-year follow-up were studied in 256 survivors of myocardial infarction (MI). On the 1-year ECGs large Q waves (MC 1.1) were more common in patients with a history of previous MI than in those with a first MI. Regression of Q-QS, ST segment, and T wave changes occurred more extensively in first MIs, whereas progression of MC Q-QS and ST segment signs tended to be common in those with recurrent MI. On the acute ECGs large Q waves were more frequent in men (52%) than in women (36%), but ST segment depression of 1 mm or more (MC 4.1) was predominant in women in both the acute and 1-year ECGs. This ECG sign was related to the advanced age of the patients. There was no significant sex difference in the regression of the Q-QS signs, but the disappearance of ST and T wave changes occurred more extensively in men. The ECG returned to normal in 12% of men with a first MI but only infrequently in women and men with recurrent MI.     

Increased diastolic blood pressure response to exercise testing when coronary artery disease is suspected. An indication of severity

One hundred and two consecutive patients with a history of chest pain or recent previous myocardial infarction underwent maximal treadmill stress testing and coronary angiography. The diastolic blood pressure response to exercise was evaluated independently of ST segment change and systolic blood pressure. In the presence of a normal systolic blood pressure response an increase in diastolic blood pressure of 15 mm Hg on at least two determinations during the same stage of exercise was considered abnormal. In 99 patients an accurate diastolic reading was possible. Of these, 61 had a normal diastolic blood pressure response; in 25 of these the ST segment was ischaemic and seven had three vessel coronary artery disease. Thirty eight patients had an abnormal diastolic blood pressure response and 27 of these had an ischaemic ST response. Of the 11 with a negative ST response for ischaemia one had left main stem disease, seven three vessel disease, and three two vessel disease. Patients with an abnormal diastolic response had greater ST depression with more angina at a reduced workload than those with a normal diastolic response. In patients with chest pain an abnormal increase in diastolic blood pressure on exercise reflects severe coronary artery disease. Although no false positives occurred in this study there was an appreciable number of false negatives (sensitivity 46%) in both patients with chest pain and those with infarction. An abnormal diastolic response therefore represents a useful additional diagnostic indicator of coronary artery disease when the ST segment response is normal or borderline. When the diastolic pressure becomes increased with or without ST changes the likelihood of severe coronary artery disease is increased.     

Relationship of prior myocardial infarction to false-positive electrocardiographic diagnosis of acute injury in patients with chest pain

Prompt management of patients suffering acute myocardial infarction requires accurate early diagnosis based on the electrocardiogram. To assess the predictive value of ST segment elevation and ST segment depression (both greater than or equal to 0.1 mV) for the diagnosis of evolving myocardial infarction, we studied 100 consecutive patients admitted to the coronary care unit of The New York Hospital with at least 30 minutes of chest pain. Of 31 patients with ST segment elevation, 26 patients (84%) evolved myocardial infarction (positive test results for serum creatine phosphokinase-MB isoenzyme fraction), while only 13 (48%) of 27 patients with ST segment depression had myocardial infarctions. Among patients with ST segment elevations with a history of prior myocardial infarction, only five (50%) of ten evolved myocardial infarction, compared with 21 of 21 with no prior infarction. False-positive diagnoses of acute injury were due to ST elevation in the area of prior Q wave infarction. Prior myocardial infarction did not alter the lower predictive value of ST segment depression for evolving infarction. We conclude that patients presenting with chest pain and ST segment elevation have approximately twice the likelihood of myocardial infarction than patients with ST segment depression; incorporation of historic information regarding prior myocardial infarction can improve the predictive value of ST segment elevations to 100% but does not improve prediction with ST segment depressions.     

Clinical presentation and prognosis of left main coronary artery disease in the 1980s

Clinical presentation and course were studied in 127 consecutive patients with angiographically proven left main coronary artery disease. Mean age was 62 (37-79) years. Thirteen patients (10%) had no history of chest pain, seven (5%) had atypical chest pain, and the remaining 107 (85%) typical angina pectoris. Eighty-two patients (65%) had unstable angina, 73 had suffered a myocardial infarction (MI) in the past, and 50 (68%) had post MI angina pectoris. The electrocardiogram was analysed in 102/125 patients during an episode of chest pain and also when they were without chest pain. Outside an episode of chest pain the ST segment was normal in 42 patients (32%), the T wave was normal in 50 patients (38%) and both the ST and T were normal in 33 patients (25%). During chest pain all patients had an abnormal ECG, the most frequent pattern being ST segment depression in leads V3, V4 and V5 (with maximal depression in V4), and ST segment elevation in leads V1 and aVR. The average number of leads with ST-T abnormalities was 6.4. A symptom-limited exercise test on a treadmill with 12-lead ECG monitoring was performed in 89 patients. The exercise test was abnormal in 88 patients (99%), most of whom (74 patients) were already in the first or second stage of the Bruce protocol. The most frequently observed abnormality was ST segment depression of 2 mm or more in leads V4, V5, and V6, and ST segment elevation in leads V1 and aVR. The systolic blood pressure during exercise fell or remained at the same level in 38 patients (43%).(ABSTRACT TRUNCATED AT 250 WORDS)     

Diagnostic value of the submaximal treadmill exercise test in the subacute phase of myocardial infarct

OBJECTIVES: To assess the diagnostic value of treadmill submaximal exercise testing (TSET), early after myocardial infarction (MI) under medical treatment, evaluating the ST changes predominantly. MATERIALS AND METHODS: 65 patients, 62 males and 3 females, mean age 52 years with demonstrated MI under clinical, electrocardiographic and enzymatic criteria were evaluated with TSET before hospital discharge. Thrombolytic therapy in acute phase of MI was done in 45 of the patients. All patients underwent angiographic studies with left ventriculography and selective coronariography. RESULTS: Of all TSET variables considered (Treadmill time, ST segment, presence of chest pain, systolic pressure, double product and presence of ventricular arrythmias) the single most important predictor for high-risk groups like left main disease and three vessels disease, was ST changes alone or associated with exercise precordial pain, with a sensitivity of 100% to left main and 83% to three vessels disease. In the thrombolytic group we did not find any differences related with reperfusion. IN CONCLUSION: TSET is a useful, noninvasive, and safe method for risk stratification after MI mainly when ST segment changes are considered alone or with stress precordial pain, predicting high risk groups, namely left main or three vessels disease patients.     

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.