Combining baseline clinical descriptors and real-time response to therapy: the incremental prognostic value of continuous ST-segment monitoring in acute myocardial infarction

Automatic classification of long-term ambulatory ECG records according to type of ischemic heart disease

BACKGROUND

Elevated transient ischemic ST segment episodes in the ambulatory electrocardiographic (AECG) records appear generally in patients with transmural ischemia (e. g. Prinzmetal's angina) while depressed ischemic episodes appear in patients with subendocardial ischemia (e. g. unstable or stable angina). Huge amount of AECG data necessitates automatic methods for analysis. We present an algorithm which determines type of transient ischemic episodes in the leads of records (elevations/depressions) and classifies AECG records according to type of ischemic heart disease (Prinzmetal's angina; coronary artery diseases excluding patients with Prinzmetal's angina; other heart diseases).

METHODS

The algorithm was developed using 24-hour AECG records of the Long Term ST Database (LTST DB). The algorithm robustly generates ST segment level function in each AECG lead of the records, and tracks time varying non-ischemic ST segment changes such as slow drifts and axis shifts to construct the ST segment reference function. The ST segment reference function is then subtracted from the ST segment level function to obtain the ST segment deviation function. Using the third statistical moment of the histogram of the ST segment deviation function, the algorithm determines deflections of leads according to type of ischemic episodes present (elevations, depressions), and then classifies records according to type of ischemic heart disease.

RESULTS

Using 74 records of the LTST DB (containing elevated or depressed ischemic episodes, mixed ischemic episodes, or no episodes), the algorithm correctly determined deflections of the majority of the leads of the records and correctly classified majority of the records with Prinzmetal's angina into the Prinzmetal's angina category (7 out of 8); majority of the records with other coronary artery diseases into the coronary artery diseases excluding patients with Prinzmetal's angina category (47 out of 55); and correctly classified one out of 11 records with other heart diseases into the other heart diseases category.

CONCLUSIONS

The developed algorithm is suitable for processing long AECG data, efficient, and correctly classified the majority of records of the LTST DB according to type of transient ischemic heart disease.

Testing of low-risk patients presenting to the emergency department with chest pain: a scientific statement from the American Heart Association

The management of low-risk patients presenting to emergency departments is a common and challenging clinical problem entailing 8 million emergency department visits annually. Although a majority of these patients do not have a life-threatening condition, the clinician must distinguish between those who require urgent treatment of a serious problem and those with more benign entities who do not require admission. Inadvertent discharge of patients with acute coronary syndrome from the emergency department is associated with increased mortality and liability, whereas inappropriate admission of patients without serious disease is neither indicated nor cost-effective. Clinical judgment and basic clinical tools (history, physical examination, and electrocardiogram) remain primary in meeting this challenge and affording early identification of low-risk patients with chest pain. Additionally, established and newer diagnostic methods have extended clinicians' diagnostic capacity in this setting. Low-risk patients presenting with chest pain are increasingly managed in chest pain units in which accelerated diagnostic protocols are performed, comprising serial electrocardiograms and cardiac injury markers to exclude acute coronary syndrome. Patients with negative findings usually complete the accelerated diagnostic protocol with a confirmatory test to exclude ischemia. This is typically an exercise treadmill test or a cardiac imaging study if the exercise treadmill test is not applicable. Rest myocardial perfusion imaging has assumed an important role in this setting. Computed tomography coronary angiography has also shown promise in this setting. A negative accelerated diagnostic protocol evaluation allows discharge, whereas patients with positive findings are admitted. This approach has been found to be safe, accurate, and cost-effective in low-risk patients presenting with chest pain.

Time to Stable ST-Segment Recovery Following Primary Angioplasty is Predictive of Regional Wall Motion Score and Clinical Outcome

We report the time to stable ST-segment reperfusion (TSTR) after primary angioplasty and its relationship with the clinical results; 137 patients who underwent primary angioplasty were included as part of the analysis. All patients had 24 hours ST-segment monitoring. Time to stable STR was defined as the beginning of ST-segment reperfusion (STR) lasting >4 hours without ST-segment reelevation. Six-month mortality was associated with slower TSTR (median 166.5 vs 6 minute, P = .001). Time to stable STR cutoff value of 136.5 minutes was identified as the best mortality predictor (area under the curve: 0.86, P = .001). Multivariate analysis identified Killip class ≥2 (P = .042), TSTR cutoff value (P = .002), and final thrombolysis myocardial infarction (TIMI) flow grade III (P = .067) as predictors of 6-month mortality. Time to stable STR may be a novel continuous electrocardiogram (ECG) parameter following primary angioplasty, which can identify high-risk patients that need to be considered for additional treatments.

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

BACKGROUND

Continuous ST-segment monitoring can be used to detect early and transient cardiac ischemia. The American Heart Association and American Association of Critical-Care Nurses recommend its use among specific patients, but such monitoring is routine practice in only about half of US hospitals.

OBJECTIVE

To determine cardiologists' awareness and practice standards regarding continuous ST-segment monitoring and the physicians' perceptions of appropriate patient selection, benefits and barriers, and usefulness of this technology.

METHODS

An electronic survey was sent to a random sample of 915 US cardiologists from a pool of 4985 certified cardiologists.

RESULTS

Of 200 responding cardiologists, 55% were unaware of the consensus guidelines. Of hospitals where respondents admitted patients, 49% had a standard of practice for using continuous ST-segment monitoring for cardiac patients. Most cardiologists agreed or strongly agreed that patients in the cardiovascular laboratory (87.5%) and intensive care unit (80.5%) should have such monitoring. Cardiologists routinely ordered ST monitoring for patients with acute coronary syndrome (67%) and after percutaneous coronary intervention (60%). The primary factor associated with higher perceptions for benefits, clinical usefulness, and past use of continuous ST-segment monitoring was whether or not hospitals in which cardiologists practiced had a standard of practice for using this monitoring. A secondary factor was awareness of published consensus guidelines for such monitoring.

CONCLUSION

Respondents (55%) were unaware of published monitoring guidelines. Hospital leaders could raise awareness by multidisciplinary review of evidence and possibly incorporating continuous ST-segment monitoring into hospitals' standards of practice.

Contrast echocardiography accurately predicts myocardial perfusion before angiography during acute myocardial infarction

OBJECTIVES

To determine whether myocardial contrast echocardiography (MCE) can quickly and accurately assess myocardial perfusion and infarct-related artery (IRA) patency before emergency angiography during acute myocardial infarction (AMI).

BACKGROUND

Despite encouraging experimental and clinical studies, the reliability and practicality of MCE in predicting IRA patency during AMI before angiography has not been proven.

METHODS

Two-dimensional echocardiography and MCE were performed in 51 patients with AMI just before emergency angiography. With knowledge of the electrocardiogram findings and regional wall motion, myocardial perfusion was assessed to predict IRA patency.

RESULTS

Myocardial perfusion studies were adequate for interpretation in 40 patients. An occluded IRA was predicted in 28 patients; the artery was occluded in 22 patients, and six patients had Thrombolysis In Myocardial Infarction (TIMI) grade 2 flow or less. A patent IRA was predicted in 12 patients; eight patients had TIMI grade 3 flow, one patient had TIMI grade 2 flow and the IRA was occluded in three patients. In one of the three patients, the appropriate view was not obtained. In another patient, collateral flow was adequate for near-normal regional wall motion, and in the last, the findings suggested reperfusion of the proximal artery with distal embolic occlusion. Taken together, MCE accurately predicted either TIMI grade 2 flow or less, or TIMI grade 3 flow in 36 of 40 patients. Sensitivity was 87.5%, specificity and positive predictive value were 100% and negative predictive power was 66.7% (P<0.001).

CONCLUSIONS

MCE, together with the electrocardiogram and regional wall motion, can be used to quickly and reliably predict IRA patency early during AMI and may be useful to facilitate a management strategy.