Thrombolysis for Acute Myocardial Infarction: Making Sense of The Clinical Trials Data

Patient delay in seeking care for heart attack symptoms: findings from focus groups conducted in five U.S. regions

BACKGROUND

Patient delay in seeking health care for heart attack symptoms is a continuuing problem in the United States.

METHODS

Investigators conducted focus groups (N = 34; 207 participants) in major U.S. regions (NE, NW, SE, SW, MW) as formative evaluation to develop a multi-center randomized community trial (the REACT Project). Target groups included adults with previous heart attacks, those at higher risk for heart attack, and bystanders to heart attacks. There were also subgroups reflecting gender and ethnicity (African-American, Hispanic-American, White).

FINDINGS

Patients, bystanders, and those at higher risk expected heart attack symptoms to present as often portrayed in the movies, that is, as sharp, crushing chest pain rather than the more common onset of initially ambiguous but gradually increasing discomfort. Patients and those at higher risk also unrealistically judge their personal risk as low, understand little about the benefits of rapid action, are generally unaware of the benefits of using EMS/9-1-1 over alternative transport, and appear to need the "permission" of health care providers or family to act. Moreover, participants reported rarely discussing heart attack symptoms and appropriate responses in advance with health care providers, spouses, or family members. Women often described heart attack as a "male problem," an important aspect of their underestimation of personal risk. African-American participants were more likely to describe negative feelings about EMS/9-1-1, particularly whether they would be transported to their hospital of choice.

CONCLUSIONS

Interventions to reduce patient delay need to address expectations about heart attack symptoms, educate about benefits and appropriate actions, and provide legitimacy for taking specific health care-seeking actions. In addition, strategy development must emphasize the role of health care providers in legitimizing the need and importance of taking rapid action in the first place.

Aortic counterpulsation may improve late patency of the occluded coronary artery in patients with early failure of thrombolytic therapy

OBJECTIVES

Using a prospective, randomized design, we tested our hypothesis that the augmentation of diastolic pressure by intraaortic balloon counterpulsation (IABP) would improve the late patency of the occluded coronary artery in patients with early failure of thrombolytic therapy.

BACKGROUND

Rescue angioplasty is often performed in patients in whom thrombolysis has failed, although 30% to 60% of the infarct-related arteries that are closed early after thrombolytic therapy will open later with conservative therapy.

METHODS

The study included 45 patients in whom thrombolysis had failed, despite treatment with intravenous tissue-type plasminogen activator (alteplase 0.75 mg/kg body weight) delivered over 60 min within 12 h of the onset of symptoms. All patients underwent coronary angiography 60 min after initiation of thrombolytic therapy (baseline), and Thrombolysis in Myocardial Infarction (TIMI) grade 0, 1 or 2 flow was defined as failed thrombolysis. The patients were randomized to groups receiving IABP for 48 h (n = 23) or conservative therapy (n = 22, control subjects) at the end of cardiac catheterization. The late patency of the infarct-related artery, the primary end point of the study, was evaluated 3 weeks after myocardial infarction. Stenosis of the infarct-related artery was measured using a computer-assisted quantitative angiographic system in blinded manner. Data are expressed as mean value +/- SEM.

RESULTS

There was no difference with regard to the baseline value for TIMI flow grade between the groups. However, 3 weeks after myocardial infarction, the patients treated with IABP had a significantly higher frequency of TIMI flow grade 3, lower residual percent stenosis and larger minimal lumen diameter of the infarct-related artery than did the control subjects (74% vs. 32%, p < 0.05; 42 +/- 5% vs. 68 +/- 6%, p < 0.01; and 1.6 +/- 0.1 vs. 0.9 +/- 0.2 mm, p < 0.01, respectively).

CONCLUSIONS

These findings suggest that in patients with early failure of thrombolytic therapy, IABP may improve late patency of the occluded coronary artery, probably due to augmented perfusion pressure.

TIMI perfusion grade 3 but not grade 2 results in improved outcome after thrombolysis for myocardial infarction. Ventriculographic, enzymatic, and electrocardiographic evidence from the TEAM-3 Study

BACKGROUND

Coronary patency has been used as a measure of thrombolysis success after acute myocardial infarction. The Thrombolysis in Myocardial Infarction (TIMI) Study Group perfusion grades have gained wide acceptance, with grades 0 (no distal flow) and 1 perfusion (minimal flow) being designated as thrombolysis failures and grades 2 (partial perfusion) and 3 (complete perfusion) as thrombolysis successes. However, the significance of the individual TIMI grades on clinical outcome has not been adequately assessed.

METHODS AND RESULTS

To evaluate the functional significance of TIMI perfusion grades, we compared 1-day coronary patency status with ventriculographic, enzymatic, and ECG indexes of acute myocardial infarction in 298 patients treated with anistreplase or alteplase within 4 hours of myocardial infarction symptom onset. Radionuclide ejection fraction was determined at 1 week and at 1 month. Perfusion grades for the entire study population were distributed as 12% (n = 37) grades 0/1, 13% (n = 40) grade 2, and 74% (n = 221) grade 3. Patency profile did not differ between the two thrombolytic regimens. Further coronary interventions were performed after the 1-day patency determination in 43% of patients (43%, 48%, 42%, respectively, in grades 0/1, 2, and 3 patients). The outcome of grade 2 patients did not differ from grades 0/1 patients in ejection fraction, enzyme peaks, ECG markers, or morbidity index. In contrast, grade 3 patients, compared with grades 0-2 patients, showed 1) a greater global ejection fraction at 1 week (54% versus 49%, p = 0.006) and at 1 month (54% versus 49%, p = 0.01), 2) a greater infarct zone ejection fraction at 1 week (41% versus 33%, p = 0.003) and at 1 month (42% versus 32%, p = 0.003), 3) smaller enzyme peaks, significant for lactate dehydrogenase, and shorter times to enzyme peaks, significant for all four enzymes, 4) a smaller QRS score at discharge and at 1 month, and 5) a trend toward a lower morbidity index.

CONCLUSIONS

Grade 3 flow predicts significantly better outcomes than lesser grades of flow and represents an important measure of reperfusion success.