Outcomes of Patients With ST-Elevation Myocardial Infarction Receiving and Not Receiving Reperfusion Therapy: The Importance of Examining All Patients.

Background: Hospitals treating patients with ST-elevation myocardial infarction (STEMI) may show good results with reperfusion treatment (fibrinolysis or primary percutaneous coronary intervention [PPCI]), but a comprehensive evaluation should factor in outcomes of patients with STEMI who do not receive reperfusion. We compared outcomes of patients receiving and not receiving reperfusion within a complete system of STEMI care by hospital type: PPCI centres, fibrinolysis centres, centres that only transfer for PPCI, and centres providing a mix of fibrinolysis and PPCI transfer.

Methods: All patients presenting to 82 Quebec hospitals with characteristic symptoms, a final diagnosis of acute myocardial infarction, and core-laboratory confirmed STEMI over two 6-month periods were studied.

Clinical Profiles Related to Timing of Death, Including In-Hospital Deaths Before Admission, in Patients With ST-Elevation Myocardial Infarction.

Patients with ST-elevation myocardial infarction (STEMI) who die in hospital before inpatient admission are generally not included in clinical studies and registries, and the clinical profiles of patients who die earlier versus later are not well defined. We aimed to characterize all patients with STEMI who arrived at emergency departments in the province of Quebec (Canada) based on inpatient admission status and when they died. All patients who presented with symptoms and core laboratory-confirmed STEMI or left bundle branch block during 6 months in 82 hospitals in Quebec were included.

Comparison of outcomes of ambulance users and nonusers in ST elevation myocardial infarction.

In a systematic province-wide evaluation of care and outcomes of ST elevation myocardial infarction (STEMI), we sought to examine whether a previously documented association between ambulance use and outcome remains after control for clinical risk factors. All 82 acute care hospitals in Quebec (Canada) that treated at least 30 acute myocardial infarctions annually participated in a 6-month evaluation in 2008 to 2009. Medical record librarians abstracted hospital chart data for consecutive patients with a discharge diagnosis of myocardial infarction who presented with characteristic symptoms and met a priori study criteria for STEMI.

Impact of ECG findings and process-of-care characteristics on the likelihood of not receiving reperfusion therapy in patients with ST-elevation myocardial infarction: results of a field evaluation.

Background: Many patients with ST-elevation myocardial infarction (STEMI) do not receive reperfusion therapy and are known to have poorer outcomes. We aimed to perform the first population-level, integrated analysis of clinical, ECG and hospital characteristics associated with non-receipt of reperfusion therapy in patients with STEMI.

Methods And Results: This systematic evaluation of STEMI care in 82 hospitals in Quebec included all patients with a discharge diagnosis of myocardial infarction, presenting with characteristic symptoms and an ECG showing STEMI as attested by at least one of two study cardiologists or left bundle branch block (LBBB).

Transfer of patients with ST-elevation myocardial infarction for primary percutaneous coronary intervention: a province-wide evaluation of "door-in to door-out" delays at the first hospital.

Background: Interhospital transfer of patients with ST-elevation myocardial infarction (STEMI) for primary percutaneous coronary intervention (PPCI) is associated with longer delays to reperfusion, related in part to turnaround ("door in" to "door out," or DIDO) time at the initial hospital. As part of a systematic, province-wide evaluation of STEMI care, we examined DIDO times and associations with patient, hospital, and process-of-care factors.

Methods And Results: We performed medical chart review for STEMI patients transferred for PPCI during a 6-month period (October 1, 2008, through March 31, 2009) and linked these data to ambulance service databases.

Information on myocardial ischemia and arrhythmias added by prehospital electrocardiograms.

Background: The prehospital electrocardiogram (ECG) allows earlier identification of acute ST-segment elevation myocardial infarction (STEMI). Its utility for detection of other acute cardiac events, as well as for transient ST-segment abnormalities no longer present when the first hospital ECG is performed, is not well characterized.

Objective: We sought to examine whether the prehospital ECG adds supplemental information to the first ECG obtained in hospital, by comparing data on possible cardiac ischemia and arrhythmias provided by the two ECGs, in ambulance patients later diagnosed as having cardiac disorders, including STEMI.

Rapid access to cardiology expertise: an innovative program to provide telephone support for family physicians.

The increasing incidence of chronic diseases in the Canadian population represents one of the biggest challenges to Canada's healthcare system and its patient population. In 2005, more than one-third of Canadians were burdened with one or more chronic diseases (Broemeling et al. 2008).

Progressive epicardial coronary blood flow reduction fails to produce ST-segment depression at normal heart rates.

ST-segment depression is commonly seen in patients with acute coronary syndromes. Most authors have attributed it to transient reductions in coronary blood flow due to nonocclusive thrombus formation on a disrupted atherosclerotic plaque and dynamic focal vasospasm at the site of coronary artery stenosis. However, ST-segment depression was never reproduced in classic animal models of coronary stenosis without the presence of tachycardia.

Simple, quantitative body surface potential map parameters in the diagnosis of remote Q wave and non-Q wave myocardial infarction.

Background: Body surface potential mapping has been shown to be a useful tool in the diagnosis and localization of remote non-Q wave and Q wave myocardial infarction, but human expertise is required to interpret the maps.

Objective: To identify quantitative body surface potential mapping parameters that could enable a computer-based diagnosis.

Methods: Body surface isopotential maps (63 unipolar leads) were recorded in 86 patients with remote Q wave and 71 patients with remote non-Q wave myocardial infarction.

Distinction between myocardial ischemia and postural changes in continuous ECG monitoring based on ST-segment amplitude and vector orientation--preliminary results.

Background: Myocardial ischemia, commonly defined as ST-segment elevation or depression on the electrocardiogram (ECG), is plagued by a large number of false positive events.

Objectives: To present a new method that attempts to distinguish between 'highly probable ischemia' and positional changes.

Methods: Continuous three-lead orthogonal ECG monitoring was performed in three groups of subjects: 16 healthy volunteers undergoing a body position change protocol, 22 patients undergoing percutaneous transluminal coronary angioplasty (PTCA) and 17 patients with acute coronary syndromes (ACS).

Aspirin, warfarin, or the combination for secondary prevention of coronary events in patients with acute coronary syndromes and prior coronary artery bypass surgery.

Background: Patients with a non-ST-elevation acute coronary syndrome and prior CABG are at high risk of a recurrent ischemic event despite aspirin therapy. This trial investigated the potential benefit of secondary prevention with warfarin.

Methods And Results: In a double-blind randomized trial, 135 patients with unstable angina or non-ST-segment elevation myocardial infarction, with prior CABG, and who were poor candidates for a revascularization procedure received therapy with aspirin and placebo+warfarin, warfarin and placebo+aspirin, or aspirin and warfarin for 12 months.

Localization of maximal ST segment displacement in various ischemic settings by orthogonal ECG: Implications for lead selection and the mechanism of ST shift.

Background: ST segment deviation conveys crucial information concerning diagnosis, therapy and prognosis during acute coronary syndromes, but the understanding of the genesis of different ST shift polarities and the rationale for optimal lead placement during ischemic monitoring are incomplete.

Patients And Methods: Ninety-nine continuous recordings were made with orthogonal X, Y and Z leads in 35 patients during ST elevation myocardial infarction (MI), in 30 patients during single vessel, elective coronary angioplasty (PTCA), and in 34 patients with unstable angina or acute non-Q wave MI. Each lead was sampled at 500 Hz, and dominant QRS-T complexes were averaged every 47 s.

New body surface isopotential map evaluation method to detect minor potential losses in non-Q-wave myocardial infarction.

Background: Potential losses caused by stable non-Q-wave myocardial infarction (MI) are too small to diagnose with the use of standard ECG. The aim of the present study was to obtain accurate diagnostic criteria for this prognostically important disease with the help of body surface mapping.

Methods And Results: Body surface potentials were recorded with the use of 63 unipolar leads in 45 patients with a non-Q-wave MI (41 to 75 years old); 24 healthy adults, 42 patients with unstable angina, and 70 patients with Q-wave MI served as reference groups.

Continuous ST-segment monitoring during coronary angioplasty using orthogonal ECG leads.

In order to characterize ST-segment shifts during transient coronary artery occlusion, 24 patients with single-vessel disease were continuously monitored during percutaneous transluminal coronary angioplasty by use of a computerized orthogonal lead system. Changes of ST-segment (J + 60 ms) in leads X, Y, and Z and of the ST vector magnitude were analyzed by using 20 microV as a threshold for significant ST-segment shift. The sensitivity and magnitude of this shift were compared among the left anterior descending, right coronary, and circumflex artery groups (11, 8, and 5 patients, respectively) during balloon inflation.

Hemorrhagic events during therapy with recombinant tissue plasminogen activator, heparin, and aspirin for unstable angina (Thrombolysis in Myocardial Ischemia, phase IIIB trial).

This study assesses the effects of invasive procedures, hemostatic and clinical variables, and doses of recombinant tissue plasminogen activator (t-PA) on hemorrhagic events in the thrombolysis in myocardial ischemia (TIMI), phase 1B clinical trial (n = 1,425). Patients seen within 24 hours of the onset of ischemic chest pain at rest were randomized using a 2 x 2 factorial design for comparison of: (1) t-PA versus placebo as initial therapy, and (2) an early invasive (coronary arteriography with percutaneous angioplasty, if feasible) versus an early conservative strategy (coronary arteriography followed by revascularization if initial medical therapy failed). All patients received conventional medication for acute ischemic syndromes, including heparin, aspirin, beta blockers, nitrates, and calcium antagonists.

PROTECT (Prospective Reinfarction Outcomes in the Thrombolytic Era Cardizem CD Trial): a randomized, double-blind clinical trial of diltiazem versus atenolol in secondary prophylaxis post non-Q wave myocardial infarction.

Objective: To describe the rationale and design of the Prospective Reinfarction Outcomes in the Thrombolytic Era Cardizem CD Trial (PROTECT).

Design: A multicentre, randomized, double-blind, parallel-group comparison of once daily beta-therapy versus heart rate lowering calcium channel blocker therapy, in the reduction of one-year nonfatal reinfarction and cardiovascular death (combined primary end-point) initiated 24 to 96 h post non-Q wave myocardial infarction.

Setting: One hundred and twenty hospitals across Canada.

Platelet membrane receptor glycoprotein IIb/IIIa antagonism in unstable angina. The Canadian Lamifiban Study.

Background: Ligand binding to the platelet membrane receptor glycoprotein (GP) IIb/IIIa, the final and obligatory step to platelet aggregation, can now be inhibited by pharmacological agents. This study was designed to evaluate the potential of lamifiban, a novel nonpeptide antagonist of GP IIb/IIIa, for the management of unstable angina.

Methods And Results: In a prospective, dose-ranging, double-blind study, 365 patients with unstable angina were randomized to an infusion of 1, 2, 4, or 5 micrograms/min of lamifiban or of placebo.

Influence of race, sex, and age on management of unstable angina and non-Q-wave myocardial infarction: The TIMI III registry.

Objective: To investigate the natural history and response to treatment of patients with unstable angina or non-Q-wave myocardial infarction (MI).

Design: Inception cohort.

Setting: Patients in general community, primary care, or referral hospitals.

A computer heart model incorporating anisotropic propagation. IV. Simulation of regional myocardial ischemia.

The main goal of this study was to simulate clinical body surface potential maps, recorded during percutaneous transluminal coronary angioplasty protocols, using a realistic geometry computer heart model. Other objectives were to address the question of reciprocal ST-segment changes observed in the 12-lead electrocardiogram during ischemia and to verify the hypothesis that the shortening of the QRS duration observed in left anterior descending (LAD) coronary artery occlusion may be explained by conduction delay in the septal His-Purkinje system. Simulation was achieved by first introducing into the heart model three transmural zones of mild, moderate, and severe ischemia for assumed occlusions in the LAD, left circumflex, and right coronary arteries.

Continuous ST segment recording during thrombolysis in acute myocardial infarction: a report on orthogonal ECG monitoring.

Background: A noninvasive, real time method is needed to identify failures of thrombolysis and evaluate new treatments in acute myocardial infarction (MI).

Objective: To study XYZ monitored ST segment evolution during thrombolysis in acute MI and to examine the correlation of ST parameters to outcome.

Design: Thirty-five patients receiving tissue plasminogen activator (tPA) (n = 18) or streptokinase (SK) (n = 17) for acute MI were monitored by vector-cardiography during the first 12 h of thrombolytic therapy.

Predictors of non-Q-wave acute myocardial infarction in patients with acute ischemic syndromes: an analysis from the Thrombolysis in Myocardial Ischemia (TIMI) III trials.

Among patients with acute ischemic syndromes, patients with non-Q-wave acute myocardial infarction (AMI) are known to be at higher risk for death, reinfarction, and other morbidity than those with unstable angina. The aim of this study was to develop a clinically useful prediction rule to assist in distinguishing, at the time of presentation, patients with non-Q-wave AMI from those with unstable angina. The TIMI IIIB trial enrolled 1,473 patients presenting with ischemic pain at rest within 24 hours who had either electrocardiographic changes or documented coronary artery disease.

QRS alterations in body surface potential distributions during percutaneous transluminal coronary angioplasty in single-vessel disease.

Body surface QRS potentials were recorded with 63 chest leads in 20 patients with proximal single-vessel disease located on either the left anterior descending coronary artery (n = 10), the right coronary artery (n = 6), or the left circumflex coronary artery (n = 4) before, during, and after percutaneous transluminal coronary angioplasty. In each case, three consecutive inflations of relatively short duration (37 +/- 14 seconds) were carried out. Electrical activity was displayed as unipolar electrograms and body surface potential maps.

Body surface potential mapping of ST-segment shift in patients undergoing percutaneous transluminal coronary angioplasty. Correlations with the ECG and vectorcardiogram.

The purpose of this study was to investigate the thoracic patterns of ST-segment shift induced by the occlusion of different coronary arteries during percutaneous transluminal coronary angioplasty. Body surface potential maps were recorded with 63 leads during sinus rhythm before, during, and after balloon inflation in 20 patients. Two patients underwent dilatation of both the right and circumflex coronary arteries.

Clinical outcomes after inferior myocardial infarction.

We studied the clinical outcomes of 46 patients followed prospectively for the initial 6 months after inferior infarction. Twenty-one patients (Group A) had no anterior ST depression (V2 to V4) present during the acute phase of the inferior infarction, whereas 25 patients (Group B) had such findings transiently. Although the clinical course during hospitalization was similar in the two groups, that after discharge differed.