Abstract 37: Long-term Outcomes Of Patients With ST-Elevation Myocardial Infarction (STEMI) With And Without Reperfusion Therapy: Results Of A Systematic Province-wide Field Evaluation In Quebec
Authors: Lambert Laurie J , Brown Kevin , Brophy James , Nasmith Jim , Segal Eli , Josep Rodés-Cabau , Carroll Céline , Giguère Maude , Bogaty Peter 
Published: March 2022

BACKGROUND:
Reperfusion treatment of patients with ST-Elevation Myocardial Infarction (STEMI) reduces short-term morbidity and mortality. There is little real-world data on longer-term benefits. Our province-wide field evaluation of STEMI care linked process-of-care data to Quebec’s medico-administrative data to determine clinical outcomes at 3 years.

METHODS:
Medical charts of patients with a final diagnosis of myocardial infarction who presented with acute symptoms to one of 80 Quebec hospitals (that treat over 95% of such patients) were reviewed. STEMI was confirmed by core laboratory analysis of the presenting electrocardiogram. Patient characteristics, process-of-care data and treatment delays were entered in a centralized website. Patients who were not sent for primary angioplasty or did not receive fibrinolysis within 4 hours of presentation were classified as having no reperfusion treatment. Treated patients were classified according to guidelines, as having timely or untimely reperfusion therapy. For follow-up to 3 years, medical insurance numbers were linked to medico-administrative data recording hospitalisations, revascularization procedures and deaths.

RESULTS:
We identified 2035 patients with STEMI or left bundle branch block during a 6 month period (2006-7). Of these, 23% (n=469) were classified as not having received reperfusion treatment. Of the remaining 1566 patients, 564 had timely treatment and 891 had delays beyond the recommended maximum. Timeliness could not be classified for 111 patients who were sent for primary angioplasty but did not undergo device deployment. At 3 years follow-up, 39% (184/469) of patients without reperfusion treatment had died compared to 12% (190/1566) of patients with reperfusion treatment (RR=3.23; 95% CI=2.72-3.85). Patients without reperfusion treatment were also more likely than treated patients to be hospitalized for heart failure (13.2% vs 4.4%; RR=3.00; 95% CI=2.16-4.16) and reinfarction (7.2% vs 4.9%; RR=1.47; 95% CI=1.00-2.18). Of patients who received reperfusion treatment beyond maximum recommended delays, 14.4% (n=128/891) died within 3 years, compared to 6.9% (n=39/564) of those who received timely treatment (RR=2.26, 95% CI=1.25-3.02). Patients with untimely treatment were more likely than those with timely treatment to be hospitalized for heart failure (5.5% vs 2.3% ; RR=2.47; 95% CI=1.33-4.56) but their risk of readmission for myocardial infarction was similar (5.3% vs 4.1%; RR=1.31; 95% CI=0.79-2.18). After adjustment for demographic and clinical factors, the risk ratios for 3-year mortality associated with non-receipt of reperfusion therapy and untimely reperfusion therapy relative to timely reperfusion were 2.38 (95% CI=1.59-3.56) and 1.61 (95% CI=1.12-2.32), respectively.

CONCLUSIONS:
This systematic evaluation of STEMI care with long-term follow-up indicates that reperfusion treatment is associated with improved clinical outcomes at 3 years. Greater benefit was observed in patients who had reperfusion therapy within guideline-recommended delays. These results emphasize the importance of increasing the use of reperfusion therapy and decreasing treatment delays.