Early Clinical Risk Stratification

The Big Heart Disease Lie

Cardiovascular Disease Causes and Possible Treatments

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The use of clinical and electrocardiogram (ECG) variables alone at the time of hospital admission in patients with ST-segment elevation myocardial infarction (STEMI) was examined in the InTIME II database of 14,114 patients treated within 4 h of symptom onset with lanoteplase (nPA) or tissue-type plasminogen activator (tPA), aspirin, and heparin to predict 30-d mortality (2). Ten independent variables accounting for 97% of the overall predictive capacity for increased 30-d mortality risk were included in the Thrombolysis in Myocardial Ischemia (TIMI) risk score for STEMI (Fig. 1). Of the 10 variables, diabetes, history of hypertension, and prior history of angina were grouped as a composite variable for a final variable set of 8 components. The mortality rate was < 1% with a score of zero and increased to 35.9% for a score >8 (Fig. 2). The InTIME risk score for patients treated with thrombolytic therapy was tested in the TIMI 9 trial and showed similar prognostic capacity. The authors then tested the score in the National Registries of Myocardial Infarction (NRMI) III registry of 84,029 patients with STEMI. Patients in NRMI III tended to be older, more often female, and have a history of coronary artery disease more often than those in the derivation set; 48% received reperfusion therapy. The risk score showed strong prognostic capacity overall and among patients with acute reperfusion therapy. However, among patients not receiving reperfusion therapy, the risk score underestimated death rates and offered lower discriminatory capacity (3).

Cannon et al. examined the use of a risk score to diagnose patients with acute coronary syndrome and non-STEMI to determine likelihood of developing a non-Q-MI (4). Four of 50 baseline variables independently predicted non-Q-MI. The four risk factors were absence of prior percutaneous transluminal coronary angioplasty (PTCA), chest pain >60 min, ST deviation on presenting ECG, and recent onset angina. The risk of non-Q-MI was 7, 19.6, 24.4, 49.9, and 70.6% for 0, 1, 2, 3, or 4 risk factors, respectively.

Timi Risk Stratification Score
Fig. 2. Predicting 30-d mortality using TIMI risk score for STEMI. Adapted with permission from ref. 2.

Age is a major risk factor for increased mortality in patients after AMI treated with thrombolytic therapy. In-hospital mortality rates were 28% in patients >85 yr in the community-based NRMI (5), 21% after 30 d in patients >65 yr in the Cooperative Cardiovascular Project, 11.2% in patients > 70 yr in the TIMI II trial after 42 d, and 17.2% in patients >70 yr after 30 d in the Global Use of Strategies To Open Occluded Arteries in Acute Coronary Syndromes (GUSTO)-l trial (6-9).

By contrast, in-hospital mortality rates were only 3, 3.8, and 1.1% in patients <55 yr, <50 yr, and <45 yr enrolled in the Myocardial Infarction Registry, TIMI II trial, and GUSTO-1 trials, respectively (5,9-11). Older patients are prone to an increased rein-farction rate and readmission for cardiac events (8). Multivessel coronary disease, important comorbid conditions, and aging myocardium with concomitant decreased myocardial reserve explains some of the increased mortality risk compared to younger individuals.

Gender

Women tend to be older than men at the time of first infarction and have a greater prevalence of associated comorbidity (12,13). The 35-d mortality rate for women compared with men was 12.5 vs 8.2% in the Fibrinolytic Therapy Trialists Group (11). In this report, 44% of patients >75 yr were women. Kober et al. (14) reported a 1-yr mortality rate of 28% for women and 21% for men in a consecutive series of 6676 patients with AMI; the increased mortality risk in women occurred relatively early (<30 d).

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