National survey of cardiologists' standard of practice for continuous ST-segment monitoring

Evaluation of ECG algorithms designed to improve detect of transient myocardial ischemia to minimize false alarms in patients with suspected acute coronary syndrome

BACKGROUND

Patients hospitalized for suspected acute coronary syndrome (ACS) are at risk for transient myocardial ischemia. During the "rule-out" phase, continuous ECG ST-segment monitoring can identify transient myocardial ischemia, even when asymptomatic. However, current ST-segment monitoring software is vastly underutilized due to false positive alarms, with resultant alarm fatigue. Current ST algorithms may contribute to alarm fatigue because; (1) they are not designed with a delay (minutes), rather alarm to brief spikes (i.e., turning, heart rate changes), and (2) alarm to changes in a single ECG lead, rather than contiguous leads.

PURPOSE

This study was designed to determine sensitivity, and specificity, of ST algorithms when accounting for; ST magnitude (100μV vs 200μV), duration, and changes in contiguous ECG leads (i.e., aVL, I, - aVR, II, aVF, III; V1, V2, V3, V4, V5, V6, V6, I).

METHODS

This was a secondary analysis from the COMPARE Study, which assessed occurrence rates for transient myocardial ischemia in hospitalized patients with suspected ACS using 12-lead Holter. Transient myocardial ischemia was identified from Holter using >100μV ST-segment ↑ or ↓, in >1 ECG lead, >1min. Algorithms tested against Holter transient myocardial ischemia were done using the University of California San Francisco (UCSF) ECG algorithm and included: (1)100μV vs 200μV any lead during a 5-min ST average; (2)100μV vs 200μV any lead >5min, (3) 100μV vs 200μV any lead during a 5-min ST average in contiguous leads, and (4) 100μV vs 200μV>5min in contiguous leads (Table below).

RESULTS

In 361 patients; mean age 63+12years, 63% male, 56% prior CAD, 43 (11%) had transient myocardial ischemia. Of the 43 patients with transient myocardial ischemia, 17 (40%) had ST-segment elevation events, and 26 (60%) ST-segment depression events. A higher proportion of patients with ST segment depression has missed ischemic events. Table shows sensitivity and specificity for the four algorithms tested.

CONCLUSIONS

Sensitivity was highly variable, due to the ST threshold selected, with the 100μV measurement point being superior to the 200μV amplitude threshold. Of all the algorithms tested, there was moderate sensitivity and specificity (70% and 68%) using the 100μV ST-segment threshold, integrated ST-segment changes in contiguous leads during a 5-min average.

Proper skin preparation and electrode placement decreases alarms on a telemetry unit

BACKGROUND

An estimated 85% to 99% of electrocardiographic (ECG) alarms are false, leading to alarm fatigue, which is associated with increased risk of death among hospitalized patients.

OBJECTIVE

The aim of this study was to examine the effect of proper skin preparation and electrode placement on frequency of ECG alarms on a telemetry unit.

METHOD

A prospective descriptive design was used to test the effect of proper skin preparation and ECG electrode placement. Purposive sampling of patients (n = 15) admitted to a telemetry hospital in a suburban Veterans Affairs Medical Center was used. Alarms were counted for 24 hours after admission, electrodes were replaced using proper technique, and alarms were counted for 24 hours after electrode change. Bootstrapping was used to double the sample size for analysis.

RESULTS

Electrocardiographic alarms decreased significantly (P < .05) after proper skin preparation and electrode placement (95% confidence interval, 1.273-82.327).

DISCUSSION

Proper skin preparation and ECG electrode placement reduced alarms. Reducing alarm frequency is vital to decreasing alarm fatigue and increasing patient safety.

The Value of Continuous ST-Segment Monitoring in the Emergency Department

Practice standards for electrocardiographic monitoring recommend continuous ST-segment monitoring (C-STM) in patients presenting to the emergency department (ED) with signs and/or symptoms of acute coronary syndrome (ACS), but few studies have evaluated its use in the ED. We compared time to diagnosis and 30-day adverse events before and after implementation of C-STM. We also evaluated the diagnostic accuracy of C-STM in detecting ischemia and infarction. We prospectively studied 163 adults (preintervention: n = 78; intervention: n = 85) in a single ED and stratified them into low (n = 51), intermediate (n = 100), or high (n = 12) risk using History, ECG, Age, Risk factors, and Troponin (HEART) scores. The principal investigator monitored participants, activating C-STM on bedside monitors in the intervention phase. We used likelihood ratios (LRs) as the measure of diagnostic accuracy. Overall, 9% of participants were diagnosed with ACS. Median time to diagnosis did not differ before and after implementation of C-STM (5.55 vs. 5.98 hr; p = 0.43). In risk-stratified analyses, no significant pre-/postdifference in time to diagnosis was found in low-, intermediate-, or high-risk participants. There was no difference in the rate of 30-day adverse events before versus after C-STM implementation (11.5% vs. 10.6%; p = 0.85). The +LR and -LR of C-STM for ischemia were 24.0 (95% confidence interval [CI]: 1.4, 412.0) and 0.3 (95% CI: 0.02, 2.9), respectively, and for infarction were 13.7 (95% CI: 1.7, 112.3) and 0.7 (95% CI: 0.3, 1.5), respectively. Use of C-STM did not provide added diagnostic benefit for patients with signs and/or symptoms of myocardial ischemia in the ED.

Among Unstable Angina and Non-ST-Elevation Myocardial Infarction Patients, Transient Myocardial Ischemia and Early Invasive Treatment Are Predictors of Major In-hospital Complications

BACKGROUND

Treatment for unstable angina (UA) or non-ST-elevation myocardial infarction (NSTEMI) is aimed at plaque stabilization to prevent infarction. Two treatment strategies are (1) invasive (ie, cardiac catheterization laboratory <24 hours after admission) or (2) selectively invasive (ie, medications with cardiac catheterization laboratory >24 hours for recurrent symptoms). However, it is not known if the frequency of transient myocardial ischemia (TMI) or complications during hospitalization varies by treatment.

PURPOSE

We aimed to (1) examine occurrence of TMI in UA/NSTEMI, (2) compare frequency of TMI by treatment pathway, and (3) determine predictors of in-hospital complications (ie, death, myocardial infarction [MI], pulmonary edema, shock, dysrhythmia with intervention).

METHODS

Hospitalized patients with coronary artery disease (ie, history of MI, percutaneous coronary intervention/stent, coronary artery bypass graft, >50% lesion via angiogram, or positive troponin) were recruited, and 12-lead electrocardiogram Holter initiated. Clinicians, blinded to Holter data, decided treatment strategy; offline analysis was done after discharge. Transient myocardial ischemia was defined as more than 1-mm ST segment ↑ or ↓, in more than 1 electrocardiographic lead, more than 1 minute.

RESULTS

Of 291 patients, 91% were white, 66% were male, 44% had prior MI, and 59% had prior percutaneous coronary intervention/stent or coronary artery bypass graft. Treatment pathway was early in 123 (42%) and selective in 168 (58%). Forty-nine (17%) had TMI: 19 (15%) early invasive, 30 (18%) selective (P = .637). Acute MI after admission was higher in patients with TMI regardless of treatment strategy (early: no TMI 4% vs yes TMI 21%; P = .020; selective: no TMI 1% vs yes TMI 13%; P = .0004). Predictors of major in-hospital complication were TMI (odds ratio, 9.9; 95% confidence interval, 3.84-25.78) and early invasive treatment (odds ratio 3.5; 95% confidence interval, 1.23-10.20).

CONCLUSIONS

In UA/NSTEMI patients treated with contemporary therapies, TMI is not uncommon. The presence of TMI and early invasive treatment are predictors of major in-hospital complications.

Individual and institutional factors affecting cardiac monitoring in coronary care units: a national survey of Chinese nurses

BACKGROUND

As cardiovascular diseases have become the leading cause of death in many countries including China, nurses are increasingly required to be abreast of technological advances and the skills necessary to manage this increasing health care problem. Chinese nurses are under pressure to provide skilled electrocardiography monitoring, and be sufficiently skilled to detect myocardial ischemia and infarction, in this large patient population. This presents a challenge for the nursing profession in China, particularly for nurses working in coronary care in a country where advancement has been so rapid, yet little research has been conducted or reported in the literature.

OBJECTIVES

The two main objectives were: to explore the demographic and educational factors that affect the use of ST-segment monitoring and correct electrode placement by CCU/ICU nurses in China; and to explore the factors both individual and institutional that affect monitoring and lead placement.

METHODS

A self-administered questionnaire was distributed to nurses in 126 randomly selected tertiary hospitals, which were stratified into three homogeneous regions across China. The instrument examined demographics, information about hospitals, electrocardiogram devices, current practice patterns and perceptions toward monitoring and lead placement. Data from 734 nurses and 59 nurse managers from 59 hospitals were analyzed using t-tests, ANOVA, Chi-square test and logistic regression.

RESULTS

Electrocardiogram monitoring was used to detect myocardial ischemia by 43.7% of respondents, and 35.1% selected leads according to electrocardiogram or angiography findings. Most (70%) agreed that monitoring for acute coronary syndrome was important, while 39.2% did so, and 15.7% were able to identify correct placement. Logistic regression revealed a significant relationship between the uses of ST-segment monitoring and number of hospital beds, continuing education and a belief in its use and ease of use. Correct electrode placement was significantly correlated with respondents from university hospitals, hospitals with more acute coronary syndrome admissions and more independent thinking nurses.

CONCLUSIONS

Despite best practice evidence, less than half of the sample used electrocardiogram monitoring to detect myocardial ischemia and the majority could not identify correct electrode placement, while ST-segment monitoring was not used routinely. This paper highlights the need for improvements in education both in universities and hospitals and discussion addresses conventions in units, which inhibit development of nurses' skills.

Continuous ST-segment monitoring: nurses' attitudes, practices, and quality of patient care

BACKGROUND

Continuous ischemia monitoring helps identify patients with acute, but often silent, myocardial ischemia. Evidence suggests nurses do not activate ischemia monitoring because they think it is difficult to use. ST-Map software incorporates graphic displays to make monitoring of ongoing ischemia easier.

OBJECTIVES

To determine if nurses' use of and attitude toward ischemia monitoring and the quality of patient care improve with use of ST-Map.

METHODS

The study included 61 nurses and 202 patients with acute coronary syndrome in a cardiac intensive care unit. Baseline data on nurses' use of and attitude toward ischemia monitoring and quality of care were obtained. Education was then provided and ST-Map software was installed on all monitors. Follow-up data were obtained 4 months later.

RESULTS

The percentage of nurses who had ever used ischemia monitoring was 13% before ST Map and 90% afterward (P < .001). The most common reason for not using ischemia monitoring before ST Map was inadequate knowledge (62%). The most common reason for liking ischemia monitoring after ST Map was knowing when a patient has ischemia (80%). Time to acquisition of a 12-lead electrocardiogram in response to symptoms or ST-segment changes was 5 to 15 minutes before ST Map and always less than 5 minutes afterward (P < .001). Time to return to the catheterization laboratory did not differ before and after ST Map.

CONCLUSIONS

ST Map was associated with more frequent use of ischemia monitoring, improved attitudes of nurses toward ischemia monitoring, and shorter time to obtaining 12-lead electrocardiograms.