Serial electrocardiograms for chest pain patients with initial nondiagnostic electrocardiograms: implications for thrombolytic therapy

Post hoc labeling an acute ECG as ischemic or non-ischemic based on clinical data: A necessary challenge

The ECG is crucial in the prehospital (and early inhospital) phase of patients with symptoms suggestive of myocardial ischemia. Therefore, new algorithms for ECG-based myocardial ischemia detection are continuously being researched. Development and validation of these algorithms require a database of acute ECGs (from the prehospital or emergency department setting) including a representative mix of cases (ischemia present) and controls (no ischemia present). Therefore, for every patient in this mix, the "truth" regarding the actual presence or absence of myocardial ischemia during the recording of the acute ECG has to be determined to compare the newly developed algorithm against. This post hoc adjudication process of determining whether an acute (either prehospitally acquired or acquired in the emergency department) ECG was made under ischemic conditions should use all available clinical data (the clinical diagnosis, cardiac imaging data, and laboratory values) of the subsequent patient's admission. Even with all data at hand, post hoc labeling a patient and their acute ECG as a myocardial ischemia case or control cannot be forced into a binary division between definite cases and definite controls. More specifically, to be used for the development of a new algorithm, the patients' ECG has to be scored for the presence or absence of myocardial ischemia at the exact moment of its recording, which renders the classification even more difficult. For instance, even though it may be plausible that myocardial ischemia was present at a given moment during the patient's admission, this is not necessarily proof that the prehospital (or early inhospital) ECG was also made in ischemic conditions: ischemia can be a fluctuating process (as is, e.g., the case in unstable angina pectoris). Therefore, post hoc classification of an acute ECG in terms of the absence or presence of ischemia requires a multipoint scale ranging between definite ischemic to definite non-ischemic, for instance using a 5-point scale (presumed non-ischemic, probably non-ischemic, uncertain, probably ischemic, presumed ischemic). To summarize, the post hoc adjudication process of ECGs of ambulance (and emergency department) patients cannot result in a binary division into definite cases and controls (i.e., patients with or without myocardial ischemia during the recording of the acute ECG), as myocardial ischemia is often dynamic rather than constant. ECGs could be labeled on a multi-point scale, in which the label represents the probability of the actual presence (or absence) of myocardial ischemia at the exact moment of the recording of that ECG. Further development of algorithms for myocardial ischemia detection should consider this concept.

Detection of STEMI Using Prehospital Serial 12-Lead Electrocardiograms

OBJECTIVE

Repeated or serial 12-lead electrocardiograms (ECGs) in the prehospital setting may improve management of patients with subtle ST-segment elevation (STE) or with a ST-segment elevation myocardial infarction (STEMI) that evolves over time. However, there is a minimal amount of scientific evidence available to support the clinical utility of this method. Our objective was to evaluate the use of serial 12-lead ECGs to detect STEMI in patients during transport in a Canadian emergency medical services (EMS) jurisdiction.

METHODS

We performed a retrospective study of suspected STEMI patients transported by EMS in the Chaudière-Appalaches region (Québec, Canada) between August 2006 and December 2013. Patients were monitored by a serial 12-lead ECG system where an averaged ECG was transmitted every 2 minutes. Following review by an emergency physician, ECGs were grouped as having either a persistent STE or a dynamic STE that evolved over time.

RESULTS

A total of 754 suspected STEMI patients were transported by EMS during the study period. Of these, 728 patients met eligibility criteria and were included in the analysis. A persistent STE was observed in 84.3% (614/728) of patients, while the remaining 15.7% (114/728) had a dynamic STE. Among those with dynamic STE, 11.1% (81/728) had 1 ST-segment change (41 no-STEMI to STEMI; 40 STEMI to no-STEMI) and 4.5% (33/728) had ≥ 2 ST-segment changes (17 no-STEMI to STEMI; 16 STEMI to no-STEMI). Overall, in 8.0% (58/728) of the cohort, STEMI was identified on a subsequent ECG following an initial no-STEMI ECG.

CONCLUSIONS

Through recognition of transient ST-segment changes during transport via the prehospital serial 12-lead ECG system, STEMI was identified in 8% of suspected STEMI patients who had an initial no-STEMI ECG. Key words: electrocardiography; emergency medical services; ST-elevation myocardial infarction; prehospital dynamic ECG.

Fragmented QRS and abnormal creatine kinase-MB are predictors of coronary artery disease in patients with angina and normal electrocardiographys

BACKGROUND/AIMS

Patients with symptoms of coronary artery disease (CAD) often display normal tracings or only nonspecific changes on electrocardiography (ECG). The aim of this study was to explore strategic elements of the ECG and other potential factors that are predictive of CAD in this scenario.

METHODS

This was an observational study of 142 patients with the chief complaint of chest pain, each of whom presented with a normal ECG and was subjected to emergency coronary angiography (CAG). Two population subsets were identified: those patients (n = 97) with no significant stenotic lesions and those (n = 45) with the significant stenotic lesions of CAD.

RESULTS

Those patients with normal or nonspecific ECGs and CAD (15.8%) were more likely to have left circumflex artery involvement (20% vs. 7%). In patients with normal ECGs and CAD (vs. normal CAG), male sex (86.7% vs. 68%, p = 0.023), creatine kinase-MB (CK-MB) levels > 10 U/L (13 vs. 10, p = 0.025), and fragmented QRS (fQRS) (38.6% vs. 21.6%, p = 0.042) occurred with greater frequency. In multivariable analysis, the following variables were significant predictors of CAD, given a normal ECG: male sex (odds ratio [OR], 2.593; 95% confidence interval [CI], 1.068 to 5.839); CK-MB (OR, 2.497; 95% CI, 0.955 to 7.039); and W- or M-shaped QRS complex (OR, 2.306; 95% CI 0.988 to 5.382).

CONCLUSIONS

In our view, male sex, elevated CK-MB (> 10 U/L), and fQRS complexes are suspects for CAD in patients with angina and unremarkable ECGs and should be considered screening tests.

Initial electrocardiogram as determinant of hospital course in ST elevation myocardial infarction

BACKGROUND

A proportion of patients with ST elevation myocardial infarction (STEMI) have an initial electrocardiogram (ECG) that is nondiagnostic and are definitively diagnosed on a subsequent ECG. Our aim was to assess whether patients with a nondiagnostic initial ECG are different than those with a diagnostic initial ECG.

METHODS

We collected demographic, ECG, medication, angiographic, and in-hospital clinical outcome data in consecutive patients undergoing primary percutaneous coronary intervention for STEMI at our institution from June 2009 to June 2013.

RESULTS

A total of 334 patients were included, 285 (85%) diagnosed on the initial ECG and 49 (15%) on a subsequent ECG. Patients with a nondiagnostic initial ECG had more comorbidities including prior congestive heart failure (14% vs. 3%, p < .001), coronary artery disease (47% vs. 24%, p = .001), diabetes (37% vs. 16%, p = .001), and hyperlipidemia (55% vs. 40%, p = .048); higher rates of chronic medication use including aspirin (47% vs. 27%, p = .005), beta-blocker (47% vs. 22%, p < .001), and statins (53% vs. 28%, p = .001); longer door-to-balloon times (106 min vs. 45 min, p < .001); lower peak troponin levels (25 ng/ml vs. 50 ng/ml, p = .004), longer diagnostic ECG to balloon times (84 min vs. 75 min, p = .006); and higher rates of a patent infarct-related artery on baseline angiography (41% vs. 24%, p = .018) which remained significant in a multivariable logistic regression model.

CONCLUSIONS

Approximately one in seven STEMI patients had an initial ECG that was nondiagnostic for STEMI. These patients had more comorbidities, higher rates of medication use, and received delayed intervention (even after the diagnosis was definitive).

Advanced Trauma Life Support (ATLS) and facial trauma: can one size fit all? Part 3: Hypovolaemia and facial injuries in the multiply injured patient

Hypovolaemic shock is a common cause of morbidity and mortality following trauma, accounting for approximately 30% to 40% of trauma deaths. Life-threatening blood loss from the maxillofacial region is uncommon, but represents one of a number of possible sites which must be rapidly identified and controlled. Bleeding from the face may not be obvious especially in awake, supine patients and it poses an obvious threat to the unprotected airway. Identification requires careful assessment. Control of bleeding in the maxillofacial region requires a number of correctly sequenced techniques. Computerized tomographic imaging is now playing an increasingly important role in identifying blood loss, especially in the chest, abdomen and pelvis. This need may potentially result in the transfer of patients, with unrecognised facial injuries, outside the relative safety of the emergency department. The concepts of the 'lethal triad' and 'biologic first hit' have resulted in new strategies in managing the profoundly shocked patient, although some of these remain controversial. Debate continues over the optimal blood pressure, fluid administration and role of surgical intervention in the actively bleeding patient. These may have an impact on the timing and extent of any proposed maxillofacial repairs, and are discussed.

Prognostic value of symptoms during a normal or nonspecific electrocardiogram in emergency department patients with potential acute coronary syndrome

OBJECTIVES

Emergency department (ED) patients with symptoms concerning for acute coronary syndrome (ACS) and a normal electrocardiogram (ECG) are at risk for adverse cardiovascular events. The authors hypothesized that patients with a normal or nonspecific ECG during symptoms have a lower risk for ACS than do those who are asymptomatic.

METHODS

This was a prospective cohort study of ED patients with potential ACS. Outcomes were acute myocardial infarction (AMI), ACS, and 30-day cardiovascular events (death, AMI, revascularization). Fisher's exact test, t-tests, and logistic regression were used for data analysis.

RESULTS

Of 2,593 patient visits, 2,007 patients had normal or nonspecific ECG findings. There were 1,196 who had symptoms during ECG, whereas 811 did not. Patients with symptoms at ECG acquisition were younger (49.9 vs. 55.2 years; p < 0.001) and were more likely to be black (70% vs. 64%; p = 0.002), female (63% vs. 58%; p = 0.03), and to have used cocaine (5% vs. 2%; p = 0.004). They were less likely to have hypertension (49% vs. 58%; p < 0.001), and diabetes (22% vs. 17%; p = 0.002). Patients with and without symptoms were equally likely to have AMI (both 2.8%; p > 0.99), ACS (10.1% vs. 11.5%; p = 0.34), and 30-day adverse outcomes (both 5.3%; p > 0.99). After adjustment for baseline cardiovascular-risk factors, odds ratios for patients with symptoms at the time of ECG acquisition were not significantly different for any of the outcomes: AMI (1.1; 95% confidence interval [CI] = 0.6 to 1.9); ACS (1.1; 95% CI = 0.8 to 1.4); or 30-day events (1.2; 95% CI = 0.8 to 1.9).

CONCLUSIONS

Patients who are symptomatic during acquisition of a normal or nonspecific ECG have rates of adverse cardiovascular events similar to those of patients without symptoms. Clinicians should not rely on the absence of ECG abnormalities during symptoms to help exclude ACS.

Is there a role for planned serial chest radiographs and abdominal ultrasound scans in the resuscitation room following trauma?

INTRODUCTION

Despite advances in trauma care, significant morbidity and mortality exists which could be reduced if all injuries were immediately identified. Two treatable factors are hypoxia and hypovolaemia which may occur secondary to haemorrhage into the chest and abdomen. Pneumothorax is also a frequent cause of preventable trauma death. Clinical examination is limited and we often rely on imaging. Anecdotally, it seemed some patients were investigated too quickly because their injuries had not evolved sufficiently enough to become detectable. In these patients, repeated assessments and imaging would, therefore, be necessary.

PATIENTS AND METHODS

This was a retrospective study looking at all patients over a 15-month period with significant chest and abdominal injuries. Patients with a chest or abdominal Abbreviated Injury Score (AIS) of 3 or above were identified. As a cross reference, those patients who required at least one chest drain, or a laparotomy within 24 h of admission were also identified. Case notes and films were reviewed with particular attention to the presence of initial 'normal' imaging.

RESULTS

A total of 1036 patients were eligible for entry into the trauma database; of these, 170 patients had chest and/or abdominal injuries coded as AIS 3 or more. We were able to identify 7 cases (4%) where initial clinical examination and imaging failed to detect either bleeding (pleural space or abdomen) or a pneumothorax. A further 5 cases were potential missed injuries, but the data were incomplete making confident inclusion in this group impossible.

CONCLUSIONS

Occult injuries are reported to have an incidence of around 2-5%. Serial imaging in the resuscitation room may enable early identification of chest and abdominal injuries. However, only 12 cases were identified making interpretation of suitable candidates for repeat imaging difficult. The question is which group of patients would benefit from planned repeat imaging before leaving the resuscitation room.

Impact of community intervention to reduce patient delay time on use of reperfusion therapy for acute myocardial infarction: rapid early action for coronary treatment (REACT) trial. REACT Study Group

BACKGROUND

Reperfusion therapy for acute myocardial infarction (AMI) is a time-dependent intervention that can reduce infarct-related morbidity and mortality. Out-of-hospital patient delay from symptom onset until emergency department (ED) presentation may reduce the expected benefit of reperfusion therapy.

OBJECTIVE

To determine the impact of a community educational intervention to reduce patient delay time on the use of reperfusion therapy for AMI.

METHODS

This was a randomized, controlled community-based trial to enhance patient recognition of AMI symptoms and encourage early ED presentation with resultant increased reperfusion therapy rates for AMI. The study took place in 44 hospitals in 20 pair-matched communities in five U.S. geographic regions. Eligible study subjects were non-institutionalized patients without chest injury (aged > or =30 years) who were admitted to participating hospitals and who received a hospital discharge diagnosis of AMI (ICD 410); n = 4,885. For outcome assessment, patients were excluded if they were without survival data (n = 402), enrolled in thrombolytic trials (n = 61), receiving reperfusion therapy >12 hours after ED arrival (n = 628), or missing symptom onset or reperfusion times (n = 781). The applied intervention was an educational program targeting community organizations and the general public, high-risk patients, and health professionals in target communities. The primary outcome was a change in the proportion of AMI patients receiving early reperfusion therapy (i.e., within one hour of ED arrival or within six hours of symptom onset). Trends in reperfusion therapy rates were determined after adjustment for patient demographics, presenting blood pressure, cardiac history, and insurance status. Four-month baseline was compared with the 18-month intervention period.

RESULTS

Of 3,013 selected AMI patients, 40% received reperfusion therapy. Eighteen percent received therapy within one hour of ED arrival (46% of treated patients), and 32% within six hours of symptom onset (80% of treated patients). No significant difference in the trends in reperfusion therapy rates was attributable to the intervention, although increases in early reperfusion therapy rates were noted during the first six months of the intervention. A significant association of early reperfusion therapy use with ambulance use was identified.

CONCLUSIONS

Community-wide educational efforts to enhance patient response to AMI symptoms may not translate into sustained changes in reperfusion practices. However, an increased odds for early reperfusion therapy use during the initiation of the intervention and the association of early therapy with ambulance use suggest that reperfusion therapy rates can be enhanced.

Effect of duration from symptom onset on the negative predictive value of a normal ECG for exclusion of acute myocardial infarction

STUDY OBJECTIVE

We hypothesized that the negative predictive value of the ECG would improve with time and assessed the effect of time elapsed from symptom onset to ED presentation on the negative predictive value, sensitivity, specificity, and positive predictive value of the initial ECG in patients presenting with symptoms suggestive of acute myocardial infarction (AMI).

METHODS

We conducted a cross-sectional study in a university teaching hospital. Our structured data instrument, completed at the time of presentation included demographics, time of onset of symptoms, history, laboratory, and ECG findings. AMI was diagnosed with the use of international diagnostic criteria. Patients were stratified according to duration of time from symptom onset at 3-hour intervals.

RESULTS

We enrolled 526 patients in the study group. The mean age was 59 years; 40% were female. The mean time elapsed from symptom onset to presentation was 185 minutes. A diagnosis of AMI was made in 104 patients (20%). The negative predictive values of a normal ECG for exclusion of AMI, stratified by duration of time from symptom onset, were: 0 to 3 hours, 93.2% (95% confidence interval [CI], 87.4% to 96.1%); 3 to 6 hours, 93.0% (95% CI, 83.0% to 98.1%); 6 to 9 hours, 92.6% (95% CI, 75.8% to 99.1%); and 9 to 12 hours, 94.1% (95% CI, 71.3% to 99.9%) (P = 1.0). The sensitivity, specificity, and positive predictive value of the ECG were similar in all groups.

CONCLUSION

The negative predictive value of a normal ECG for exclusion of AMI does not improve as the duration of time from symptom onset to presentation increases. Normal ECG findings cannot be used to rule out an AMI, even those obtained up to 12 hours after symptom onset.