"Inadvertent" thrombolytic administration in patients without myocardial infarction: clinical features and outcome

Accuracy of Post-thrombolysis ST-segment Reduction as an Adequate Reperfusion Predictor in the Pharmaco-Invasive Approach

Fundamento

A intervenção coronária percutânea primária é considerada o “padrão-ouro” para reperfusão coronária. Entretanto, quando não disponível, a estratégia fármaco-invasiva é método alternativo, e o eletrocardiograma (ECG) tem sido utilizado para identificar sucesso na reperfusão.

Objetivos

Nosso estudo teve como objetivo examinar alterações no segmento-ST pós-lise e seu poder de prever a recanalização, usando os escores angiográficos TIMI e blush miocárdio (MBG) como critério de reperfusão ideal.

Métodos

Foram estudados 2.215 pacientes com infarto agudo do miocárdio com supra-ST submetidos à fibrinólise [(Tenecteplase)-TNK] e encaminhados para angiografia coronária em até 24 h pós-fibrinólise ou imediatamente encaminhados à terapia de resgate. O ECG foi realizado pré-TNK e 60 min-pós. Os pacientes foram categorizados em dois grupos: aqueles com reperfusão ideal (TIMI-3 e MBG-3) e aqueles com reperfusão inadequada (fluxo TIMI <3). Foi definido o critério de reperfusão do ECG pela redução do segmento ST >50%. Consideramos p-valor <0,05 para as análises, com testes bicaudais.

Resultados

O critério de reperfusão pelo ECG apresentou valor preditivo positivo de 56%; valor preditivo negativo de 66%; sensibilidade de 79%; e especificidade de 40%. Houve fraca correlação positiva entre a redução do segmento-ST e os dados angiográficos de reperfusão ideal (r = 0,21; p <0,001) e baixa precisão diagnóstica, com AUC de 0,60 (IC-95%; 0,57-0,62).

Conclusão

Em nossos resultados, a redução do segmento-ST não conseguiu identificar com precisão os pacientes com reperfusão angiográfica apropriada. Portanto, mesmo pacientes com reperfusão aparentemente bem-sucedida devem ser encaminhados à angiografia brevemente, a fim de garantir fluxo coronário macro e microvascular adequados.

Chameleons: Electrocardiogram Imitators of ST-Segment Elevation Myocardial Infarction

The imperative for timely reperfusion therapy for patients presenting with ST-segment elevation myocardial infarction (STEMI) underscores the need for clinicians to have an understanding of how to distinguish patterns of STEMI from its imitators. These imitating diagnoses may confound an evaluation, potentially delaying necessary therapy. Although numerous diagnoses may mimic STEMI, several morphologic clues may allow the physician to determine if the pattern is concerning for either STEMI or a mimicking diagnosis. Furthermore, obtaining a satisfactory history, comparing previous electrocardiograms, and assessing serial tests may provide valuable clues.

Thrombolytic-related complication in a case of misdiagnosed myocardial infarction

The importance of early thrombolysis in acute myocardial infarction has been highlighted in several large trials. The clinical decision is often taken by physicians who need to take a rapid action with the risk of misdiagnosing non-coronary events that mimic myocardial infarction. Here we describe a case of acute pericarditis in a 37-year-old man whom received thrombolysis and developed a sudden hemorrhagic pericardial effusion that evolved rapidly into a cardiac tamponade. These errors leading to lethal thrombolysis complications have been surprisingly rare; but a correct diagnosis of aortic dissection or hemorrhagic pericarditis needs to be stressed because even after obtaining the correct diagnosis, the prolonged disturbance of hemostasis prevents a rapid therapy being instigated.

Electrocardiographic criteria for ST-elevation myocardial infarction in patients with left ventricular hypertrophy

Patients with electrocardiographic (ECG) left ventricular hypertrophy (LVH) have repolarization abnormalities of the ST segment that may be confused with an ischemic current of injury. We analyzed the ACTIVATE-SF database, a registry of consecutive emergency department ST-segment elevation (STE) myocardial infarction diagnoses from 2 medical centers. Univariate analysis was performed to identify ECG variables associated with presence of an angiographic culprit lesion. Recursive partitioning was then applied to identify a clinical decision-making rule that maximizes sensitivity and specificity for presence of an angiographic culprit lesion. Seventy-nine patients with ECG LVH underwent emergency cardiac catheterization for primary angioplasty. Patients with a culprit lesion had greater magnitude of STE (3.0 ± 1.8 vs 1.9 ± 1.0 mm, p = 0.005), more leads with STE (3.1 ± 1.6 vs 2.0 ± 1.8 leads, p = 0.002), and a greater ratio of STE to R-S-wave magnitude (median 25% vs 9.2%, p = 0.003). Univariate application of ECG criteria had limited sensitivity and a high false-positive rate for identifying patients with an angiographic culprit lesion. In patients with anterior territory STE, using a ratio of ST segment to R-S-wave magnitude ≥25% as a diagnostic criteria for STE myocardial infarction significantly improved specificity for an angiographic culprit lesion without decreasing sensitivity (c-statistic 0.82), with a net reclassification improvement of 37%. In conclusion, application of an ST segment to R-S-wave magnitude ≥25% rule may augment current criteria for determining which patients with ECG LVH should undergo primary angioplasty.

Prevalence, etiology and outcome of catheterization laboratory false alarms in patients with suspected ST-elevation myocardial infarction

INTRODUCTION AND OBJECTIVES

To investigate the prevalence, causes and outcome of catheterization laboratory false alarms (CLFAs) in a regional primary angioplasty network.

METHODS

A prospective registry of 1,662 patients referred for primary angioplasty between January 2003 and August 2008 was reviewed to identify CLFAs (i.e. when no culprit coronary lesion could be found).

RESULTS

No culprit coronary lesion could be identified in 120 patients (7.2%; 95% confidence interval [CI], 5.9-8.5%). Of these, 104 (6.3%, 95% CI, 5.1-7.4%) had a discharge diagnosis other than ST-elevation myocardial infarction, 91 (5.5%; 95% CI, 4.3-6.6%) had no significant coronary disease, and 64 (3.8%; 95% CI, 2.9-4.8%) tested negative for cardiac biomarkers. The most frequent alternative diagnoses were: previous Q-wave myocardial infarction (18 cases), nonspecific ST-segment abnormalities (11), pericarditis (10) and transient apical dyskinesia (10). The 30-day mortality rate was similar in patients with and without culprit lesions (5.8% vs. 5.8%; P=.99). The prevalence of CLFAs was slightly higher in patients not previously evaluated by a cardiologist and referred from emergency departments in hospitals without catheterization laboratories than in those referred by cardiologists from emergency departments at hospitals with such facilities (9.5% vs. 6.1%; P=.02; odds ratio=1.64; 95% CI, 1.08-2.5). The prevalence of CLFAs was not significantly higher in patients referred by physicians with out-of-hospital emergency medical services (7.2%; P=.51; odds ratio=1.37; 95% CI, 0.79-2.37).

CONCLUSIONS

The prevalence of CLFAs was 7.2%, with the criterion of no culprit coronary lesion. Our findings suggest that different patterns of referral to catheterization laboratories could account for small variations in the prevalence of CLFAs.

Prevalence, etiology and outcome of catheterization laboratory false alarms in patients with suspected ST-elevation myocardial infarction

INTRODUCTION AND OBJECTIVES

To investigate the prevalence, causes and outcome of catheterization laboratory false alarms (CLFAs) in a regional primary angioplasty network.

METHODS

A prospective registry of 1,662 patients referred for primary angioplasty between January 2003 and August 2008 was reviewed to identify CLFAs (i.e. when no culprit coronary lesion could be found).

RESULTS

No culprit coronary lesion could be identified in 120 patients (7.2%; 95% confidence interval [CI], 5.9-8.5%). Of these, 104 (6.3%, 95% CI, 5.1-7.4%) had a discharge diagnosis other than ST-elevation myocardial infarction, 91 (5.5%; 95% CI, 4.3-6.6%) had no significant coronary disease, and 64 (3.8%; 95% CI, 2.9-4.8%) tested negative for cardiac biomarkers. The most frequent alternative diagnoses were: previous Q-wave myocardial infarction (18 cases), nonspecific ST-segment abnormalities (11), pericarditis (10) and transient apical dyskinesia (10). The 30-day mortality rate was similar in patients with and without culprit lesions (5.8% vs. 5.8%; P=.99). The prevalence of CLFAs was slightly higher in patients not previously evaluated by a cardiologist and referred from emergency departments in hospitals without catheterization laboratories than in those referred by cardiologists from emergency departments at hospitals with such facilities (9.5% vs. 6.1%; P=.02; odds ratio=1.64; 95% CI, 1.08-2.5). The prevalence of CLFAs was not significantly higher in patients referred by physicians with out-of-hospital emergency medical services (7.2%; P=.51; odds ratio=1.37; 95% CI, 0.79-2.37).

CONCLUSIONS

The prevalence of CLFAs was 7.2%, with the criterion of no culprit coronary lesion. Our findings suggest that different patterns of referral to catheterization laboratories could account for small variations in the prevalence of CLFAs.

Conditions mimicking acute ST-segment elevation myocardial infarction in patients referred for primary percutaneous coronary intervention

BACKGROUND/OBJECTIVES.: A rapid diagnosis of ST-segment elevation myocardial infarction (STEMI) is mandatory for optimal treatment. However, a small proportion of patients with suspected STEMI suffer from other conditions. Although case reports have described these conditions, a contemporary systematic analysis is lacking. We report the incidence, clinical characteristics and outcome of patients with suspected STEMI referred for primary percutaneous coronary intervention (PCI) with a final diagnosis other than STEMI. METHODS.: From January 2004 to July 2005, 820 consecutive patients were included with suspected STEMI who were referred for primary PCI to a university medical centre, based on a predefined protocol. Clinical characteristics, final diagnosis and outcome were obtained from patient charts and databases. RESULTS.: In 19 patients (2.3%), a final diagnosis other than myocardial infarction was established: coronary aneurysm (n=1), (myo)pericarditis (n=5), cardiomyopathy (n=2), Brugada syndrome (n=1), aortic stenosis (n=1), aortic dissection (n=3), subarachnoidal haemorrhage (n=2), pneumonia (n=1), chronic obstructive pulmonary disease (n=1), mediastinal tumour (n=1), and peritonitis after recent abdominal surgery (n=1). These patients less often reported previous symptoms of angina (p<0.001), smoking (p<0.05) and a positive family history of cardiovascular diseases (p<0.05) than STEMI patients. Mortality at 30 days was 16%. CONCLUSION.: A 2.3% incidence of conditions mimicking STEMI was found in patients referred for primary PCI. A high clinical suspicion of conditions mimicking STEMI remains necessary. (Neth Heart J 2008;16:325-31.).

Frequency of and inappropriate treatment of misdiagnosis of acute aortic dissection

Acute aortic syndrome (AAS) comprises acute aortic dissection, intramural hematoma, and penetrating ulcer of the aorta. The importance of accurate, rapid diagnosis and intervention for AAS is underscored by its clinical and epidemiologic overlap with acute coronary syndrome and by the risks of inappropriate treatment with antithrombotic agents. To explore these concerns, the recognition, management, and outcomes of AAS in the contemporary experience of a tertiary referral center were reviewed. Sixty-six consecutive patients with AAS admitted from January 2000 to December 2004 were identified, and their records reviewed. Misdiagnosis occurred in 39% (n = 26) and was associated with longer time to correct diagnosis (mean +/- SEM 51 +/- 12 vs 15 +/- 5 hours, p = 0.003). Acute coronary syndrome was the most common misdiagnosis, resulting in inappropriate treatment with acetylsalicylic acid in 26 (100%), clopidogrel in 1 (4%), heparin in 22 (85%), and fibrinolytic agents in 3 (12%). Exposure to antithrombotic agents was associated with higher rates of major bleeding (38% vs 13%) and a trend toward greater in-hospital mortality (27% vs 13%) (p = 0.02 for combined end point). Antithrombotic agent administration was also associated with increased hemorrhagic pericardial fluid (50% vs 25%), hemorrhagic pleural effusion (15% vs 3%), and hemodynamic instability (30% vs 13%) (p = 0.02 for combined end point). In conclusion, AAS is frequently confused with acute coronary syndrome, leading to delayed diagnosis and clinically significant bleeding as a consequence of inappropriate treatment with antithrombotic agents.

Electrocardiographic abnormalities mimicking myocardial infarction in a patient with intracranial haemorrhage: a possible pitfall for prehospital thrombolysis

The electrocardiogram, when applied in the prehospital setting, has a significant effect on a patient with chest pain. The potential effect includes both diagnostic and therapeutic issues, including the diagnosis of acute myocardial infarction and the indication for thrombolysis or invasive procedures. We report the case of a man who suffered from a syncope, with a prehospital electrocardiogram showing prominent ST-segment elevation. Out-of-hospital thrombolytic therapy was planned by the emergency department. Fortunately, thrombolysis did not start because the patient fared worse. He was taken to the emergency department and, because of mental status impairment, it was decided to perform a cranial computed tomographic scan. The diagnosis shifted to a haemorrhagic stroke. According to the guidelines, prehospital thrombolysis would have been inappropriate in this case because the patient did not have any chest discomfort. The pathophysiological mechanisms of electrocardiographic abnormalities in the setting of intracranial haemorrhage are reviewed, as well as the issue of thrombolysis administered or planned only on the basis of an electrocardiogram.

Rationale for establishing regional ST-elevation myocardial infarction receiving center (SRC) networks

Recent developments have provided a unique opportunity for the organization of regional ST-elevation myocardial infarction (STEMI) receiving center (SRC) networks. Because cumulative evidence has demonstrated that rapid primary percutaneous coronary intervention (PCI) is the most effective reperfusion strategy for acute STEMI, the development of integrated SRC networks could extend the benefits of primary PCI to a much larger segment of the US population. Factors that favor the development of regional SRC networks include results from recently published clinical trials, insight into contemporary STEMI treatment patterns from observational registries, experience with the nation's current trauma system, and technological advances. In addition, the 2004 American College of Cardiology/American Heart Association STEMI guidelines have specified that optimal "first medical contact-to-balloon" times should be <90 minutes, so a clear benchmark for timely reperfusion has been established. Achievement of this benchmark will require improvements in the current process of care as well as increased multidisciplinary cooperation between emergency medical services, emergency medicine physicians, and cardiologists. Two types of regional SRC networks have already begun to evolve in role-model cities, including prehospital cardiac triage and interhospital transfer. Regional coordination of SRC networks is needed to ensure quality monitoring and to delineate the ideal reperfusion strategy for a given community based on available resources and expertise.

Value of plasma fibrin D-dimers for detection of acute aortic dissection

OBJECTIVES

The purpose of this research was to assess the value of systemic inflammatory biomarkers in the detection of acute aortic dissection (AD).

BACKGROUND

Rapid diagnosis and initiation of treatment is pivotal for patients with acute AD. So far, there is no laboratory test to aid the diagnosis.

METHODS

Plasma fibrin D-dimers, white blood cell (WBC) count, C-reactive protein (CRP), and fibrinogen were determined in 64 chest-pain (CP) patients (acute AD, n = 16; pulmonary embolism [PE], n = 16; acute myocardial infarction [AMI], n = 16; non-cardiac CP, n = 16); 32 asymptomatic patients with chronic AD served as a control group.

RESULTS

All acute AD patients showed highly elevated D-dimer values that were similar to PE patients (2,238 +/- 1,765 microg/l vs. 1,531 +/- 837 microg/l, p = 0.15) but significantly higher than in chronic AD, AMI, or CP patients (p < 0.001). The WBC count was significantly increased in patients with acute AD compared with the other groups (p < 0.001); in addition, CRP values differed only non-significantly from PE patients(p = 0.71). There were no differences in the fibrinogen levels between the groups.

CONCLUSIONS

D-dimers are highly elevated in both acute PE and acute AD. Patients with acute AD show significant systemic inflammatory reactions. Measurement of D-dimers may be a valuable addition to the current diagnostic work-up of patients with suspected AD.

Facteurs de risque de mortalité après chirurgie pour dissection aortique de type A : impact des traitements antithrombotiques préopératoires

OBJECTIVE

The purpose of this investigation was to study the incidence and consequences of anticoagulant therapy in the surgical management of acute aortic dissections.

STUDY DESIGN

Retrospective study.

PATIENTS AND METHODS

We reviewed all acute type A aortic dissections that were surgically managed in our institution from 1 January 1990 to 31 December 2000. Survival outcome and characteristics potentially associated with survival were abstracted from patient records. We screened preoperative electrocardiograms (ECG) and anticoagulant therapy.

RESULTS

ST segment elevation incidence was 14% and preoperative anticoagulant therapy occurred in 63 (20%) cases as follow: aspirin 12%, aspirin + heparin 6%, thrombolysis 1%. Overall mortality was 22%. Time between pain and surgery was not statistically different between anticoagulant therapy and standard group. Administration of antithrombotic agents before admission in -hospital increased significantly mortality (Odds ratio (OR) = 2.02; IC [1.1-3.71]; p = 0.023). Other risk factors for death were preoperative circulatory failure (OR = 8.28 [4.23-16.24], p < 0.0001), preoperative cardiac arrest (OR = 21.92 [7.16-67.14], p < 0.0001), preoperative circulatory arrest (OR = 2.79 [1.60-4.88], p = 0.0003), preoperative cerebral perfusion (OR = 2.45 [1.18-5.05], p = 0.016), postoperative circulatory failure (OR = 3.37 [1.85-6.17], p < 0.0001), postoperative cardiac arrest (OR = 9.92 [3.49-28.21], p < 0.0001), postoperative serum creatinine >150 micromol/l (OR = 4.55 [2.43-8.50], p < 0.0001), postoperative dialysis (OR = 5.63 [2.44-13.20], p < 0.0001), more than 7 days of post-operative ventilation (OR = 23.44 [12.0-45.7], p < 0.0001).

DISCUSSION

In our experience, 20% of acute type A aortic dissections had received a preoperative anticoagulant therapy. This event is an independent risk factor of in-hospital death and is more frequent in case of ischaemic ECG abnormalities.

Prehospital versus hospital fibrinolytic therapy using automated versus cardiologist electrocardiographic diagnosis of myocardial infarction: abortion of myocardial infarction and unjustified fibrinolytic therapy

BACKGROUND

This study investigated the incidence of abortion of myocardial infarction and of unjustified fibrinolysis by using automated versus cardiologist-assisted diagnosis of acute ST-elevation myocardial infarction. The results of prehospital diagnosis and treatment (2 cities in the Netherlands) were compared with those of inhospital treatment. Unjustified fibrinolysis must be differentiated from justified thrombolysis resulting in aborted myocardial infarction. Both have the absence of a significant rise in cardiac enzymes in common. In aborted myocardial infarction, this is a result of timely reperfusion; in unjustified thrombolysis, this is the result of an incorrect diagnosis.

METHODS

In the city of Rotterdam, 118 patients were treated before hospitalization for myocardial infarction, diagnosed through the use of a mobile computer electrocardiogram; in the city of Nijmegen, 132 patients were treated before hospitalization with the use of transtelephonic transmission of the electrocardiogram to the coronary care unit and judged by a cardiologist. Their data were compared with those of 269 patients treated inhospital in the city of Arnhem, using the same electrocardiographic criteria. Abortion of myocardial infarction was diagnosed as the absence of a significant rise in cardiac enzymes and the presence of resolution of chest pain and 50% of ST-segment deviation within 2 hours after onset of therapy. Lacking these, the diagnosis of unjustified fibrinolytic therapy was made.

RESULTS

Unjustified treatment occurred in 8 (3.2%) prehospital-treated patients (4 in Rotterdam and 4 in Nijmegen). Of the inhospital-treated patients in Arnhem, 5 (1.9%) were treated unjustifiably (P =.49). Aborted myocardial infarction occurred in 15.3% and 18.2% in Rotterdam and Nijmegen, respectively, against 4.5% in inhospital treatment in Arnhem (P <.001).

CONCLUSIONS

Abortion of myocardial infarction is associated with prehospital thrombolysis. Unjustified fibrinolysis for acute myocardial infarction occurs in prehospital fibrinolysis as frequently as in the inhospital setting. The use of different electrocardiographic methods for diagnosing acute myocardial infarction does not appear to make any difference.

Impact of a region-wide approach to improving systems for heart attack care: the West Midlands thrombolysis project

OBJECTIVE

To describe changes in delay to administration of thrombolytic therapy associated with a region-wide audit.

DESIGN

Observational study of patients admitted with suspected myocardial infarction (MI) based on continuous audit.

SUBJECTS

18877 patients admitted to 23 hospitals with suspected MI between April 1995 and March 1998.

RESULTS

Of 11232 patients with a discharge diagnosis of definite MI, 8802 (46.6%) received thrombolytic therapy during hospitalisation, with 5155 patients eligible for treatment on admission to hospital on the basis of established indications. Call-to-needle time for those eligible for treatment on admission fell from median 105 min in the first year of the project to 85 min in year 3 (P<0.001), and door-to-needle time fell from 45 to 35 min (P<0.001). Forty percent of eligible patients were treated within the then current national standard of 90 min from time of call for help, with nearly 49% in the final year and 20% being treated within the new national standard of 60 min, by the third year.

CONCLUSION

The proportion of eligible patients receiving thrombolysis within 1 h of the call for help doubled during the 3-year project but the majority of patients still wait longer than 60-min 'call-to-needle'. New systems to reduce delays to administration of thrombolysis to within 60 min of call for help are required, including consideration of pre-hospital treatment.

Misdiagnosis of stroke in tissue plasminogen activator–treated patients

STUDY OBJECTIVE

Misdiagnosis of acute ischemic stroke is a risk inherent in treating patients with acute deficits, yet few data exist on the problem. We report an evaluation of emergency department misdiagnoses in patients treated with tissue plasminogen activator for acute ischemic stroke.

METHODS

We conducted an observational study of 151 consecutive patients treated without an acute stroke team. Initial diagnosis was compared with interim and hospital discharge diagnoses. Separate analyses were performed for patients without a final diagnosis of acute ischemic stroke and for those without a final diagnosis of either acute ischemic stroke or transient ischemic attack, combined.

RESULTS

Ten of 151 patients (7%; 95% confidence interval [CI] 3% to 12%) had final diagnoses that did not include acute ischemic stroke. Six of 151 (4%; 95% CI 1% to 8%) had a final diagnosis other than acute ischemic stroke or transient ischemic attack (conversion disorder [4], complex migraine [1], and Todd's paralysis [1]). These "stroke mimics" had no intracranial hemorrhage (0%; 95% CI 0% to 31%), had less disability at discharge (modified Rankin Scale score mean+/-SD, 2.2+/-1.3 versus 3.2+/-1.8), and were younger (mean age+/-SD, 47+/-21 years versus 68+/-15 years) than patients with acute ischemic stroke or transient ischemic attack. An additional 4 (3%) patients had interim diagnoses other than acute ischemic stroke, all subsequently changed to acute ischemic stroke after magnetic resonance imaging or computed tomography.

CONCLUSION

These data show that in a 4-hospital system without an acute stroke team, thrombolytic treatment of patients with diagnoses mimicking stroke was infrequent, and hemorrhagic complications did not occur in any patients without an acute ischemic stroke. However, because the number of mimics was small, safety cannot be ensured with statistical confidence.

Abortion of acute ST segment elevation myocardial infarction after reperfusion: incidence, patients' characteristics, and prognosis

OBJECTIVES

To study the incidence and patient characteristics of aborted myocardial infarction in both prehospital and in-hospital thrombolysis.

DESIGN

Retrospective, controlled, observational study.

SETTING

Two cities in the Netherlands, one with prehospital thrombolysis, one with in-hospital treatment.

PATIENTS

475 patients with suspected acute ST elevation myocardial infarction treated before admission to hospital, 269 patients treated in hospital.

MAIN OUTCOME MEASURES

Aborted myocardial infarction, defined as the combination of subsiding of cumulative ST segment elevation and depression to < 50% of the level at presentation, together with a rise of creatine kinase of less than twice the upper normal concentration. A stepwise regression analysis was used to test independent predictors for aborted myocardial infarction.

RESULTS

After correction for "unjustified" thrombolysis, 17.1% of the 468 prehospital treated patients and 4.5% of the 264 in-hospital treated patients fulfilled the criteria for aborted myocardial infarction. There was no difference in age, sex, risk factors, haemodynamic status, and infarct location of aborted myocardial infarction compared with established myocardial infarction. Time to treatment was shorter in the patients with aborted myocardial infarction (86 versus 123 minutes, p = 0.05). A shorter time to treatment, lower ST elevation at presentation, and higher incidence of preinfarction angina were independent predictors for aborted myocardial infarction. Aborted myocardial infarction had a 12 month mortality of 2.2%, significantly less than the 11.6% of established myocardial infarction.

CONCLUSION

Prehospital thrombolysis is associated with a fourfold increase of aborted myocardial infarction compared with in-hospital treatment. A shorter time to treatment, a lower ST elevation, and a higher incidence of preinfarction angina were predictors of aborted myocardial infarction.

Electrocardiographic presentation of blacks with first myocardial infarction does not explain race differences in thrombolysis administration

BACKGROUND

Previous studies have suggested that thrombolysis is used less often in blacks than in whites. However, whether the greater prevalence of contraindications or less specific electrocardiographic manifestations of myocardial infarction (MI) account for this difference is unclear.

METHODS AND RESULTS

We studied 498 consecutive patients (32% blacks) with first MI. Initial electrocardiograms were analyzed, blinded to race and outcome, for ST-segment deviation and bundle branch block to determine eligibility for thrombolysis. The relation of electrocardiographic eligibility for thrombolysis and actual use of thrombolysis in both races was explored. Among blacks, 45% received thrombolysis compared with 66% of whites (P <.001). A similar proportion of blacks and whites were eligible for thrombolysis (59% and 66% respectively, P =. 116), but 62% of electrocardiography-eligible blacks were treated with thrombolysis compared with 75% of whites (P =.016). After accounting for eligibility for electrocardiography and other clinical variables likely to affect the decision to administer thrombolysis by means of conditional logistic regression, blacks were still less likely to receive thrombolysis (relative risk 0.73; 95% confidence interval 0.55 to 0.97).

CONCLUSIONS

We conclude that the differences in thrombolysis administration to blacks and whites are not accounted for by differences in electrocardiographic presentation or other measured variables. Unmeasured differences in clinical presentation of MI may explain racial differences in thrombolysis and merits further study.

Effect of prehospital thrombolysis on aborting acute myocardial infarction

On administering thrombolysis in a prehospital setting, we found a threefold increase in the incidence of abortion of myocardial infarction, compared with the in-hospital program of a nearby hospital. Assessment of aborted myocardial infarction may be a better criterion for the efficacy of early thrombolysis than mortality data.

Electrocardiographic manifestations: acute myopericarditis

Acute, or so-called "dry," myopericarditis occurs in the presence of diffuse inflammation of the pericardial sac and superficial epicardium from a multitude of infectious and inflammatory processes. This inflammation results in a current of myocardial injury resulting from the epicardial irritation manifested by a number of electrocardiographic findings. Classically, the electrocardiographic changes have been described as an evolution through several distinct stages involving ST segment elevation with PR segment depression, normalization of the ST segment abnormality with T wave inversion, and eventual normalization of the electrocardiogram over a period of days to several weeks. The following discussion focuses on the electrocardiographic manifestations of acute myopericarditis and includes findings useful in establishing the diagnosis as well as distinguishing the disease from other syndromes, particularly acute myocardial infarction.

Lower thrombolytic use for African Americans with myocardial infarction: an influence of clinical presentation?

BACKGROUND

After myocardial infarction, African Americans have been reported to undergo fewer catheterization and revascularization procedures than whites, but few studies have addressed racial variations in the delivery of thrombolytic therapy.

METHODS

We conducted a retrospective analysis of data prospectively collected on consecutive patients admitted with acute myocardial infarction to the 16-bed coronary care unit of a large, urban teaching hospital.

RESULTS

Over a 5-year period, 1948 consecutive patients were admitted with acute myocardial infarction to a single coronary care unit. Thrombolysis was administered to 19% of 1024 African Americans and 29% of 924 whites (P <.01). The initial diagnostic impression on admission was "definite" infarction less often in African Americans (30%) than in whites (43%, P <.001), a difference that appeared to largely account for the difference in thrombolytic administration in a multivariable model. Mortality adjusted for age and concomitant illnesses was similar in African Americans compared with whites (relative risk 1.0, 95% confidence interval 0.78 to 1.51).

CONCLUSIONS

Much of the racial variation in thrombolytic administration could be accounted for by differences in clinical presentation, an issue that requires further study.

Measurement of cardiac troponin T is an effective method for predicting complications among emergency department patients with chest pain

STUDY OBJECTIVES

To determine the test performance characteristics of serum cardiac troponin T (cTnT) measurement for diagnosis of acute myocardial infarction (AMI), and to determine the ability of cTnT to stratify emergency department patients with chest pain into high- and low-risk groups for cardiac complications.

METHODS

We conducted a prospective observational cohort study with convenience sampling in a tertiary care, urban ED. The study sample comprised 667 patients presenting to the ED with a complaint of chest pain or other symptoms suggesting acute ischemic coronary syndrome (AICS). Patients were assigned to different blood sampling protocols for cTnT therapy on the basis of their ECG at presentation: nondiagnostic for AMI at 0, 3, 6, 9, 12, and 24 hours after ED presentation; or ECG diagnostic for AMI at 0, 1, 2, 3, 4, 5, 6, 7, 8, 9, 12, 18, and 24 hours after ED presentation.

RESULTS

Of 667 patients, 34 had AMI diagnosed within 24 hours of ED arrival. Using a .2 microgram/L discrimination level for cTnT, sensitivity for AMI within 24 hours of ED arrival was 97% (95% confidence interval, 91.4% to 99.9%), and specificity was 92% (89.8%-94.1%). When the effects of age, race, sex, and creatine kinase-MB isoenzyme subunit test results were controlled, a patient with cTnT of .2 microgram/L or greater was 3.5 (1.4 to 9.1) times more likely to have a cardiac complication within 60 days of ED arrival than a patient with a cTnT value below .2 microgram/L.

CONCLUSION

Measurement of cTnT will accurately identify myocardial necrosis in patients presenting to the ED with possible AICS. Elevated cTnT values identify patients at increased risk of cardiac complications.