Changing Face of Acute Myocardial Infarction in East London: A Prospective Cohort Study of Trends in Management and Outcome in the Reperfusion Era

Abstract

Aims To define the trends in management and outcome of acute myocardial infarction over the first decade since the widespread adoption of thrombolytic therapy.

Methods Prospective cohort study of 1737 consecutive patients with acute myocardial infarction admitted for coronary care between January 1988 and December 1997.

Results Trend analysis with comparison of early (1988-1992) and late (1993-1997) cohorts showed significant increments in median age (interquartile range) from 62 (54-70) to 64 (55-72) years (P < 0.01) but the proportion of smokers fell from 72.7% to 65.8% (P < 0.01). The proportion of patients receiving thrombolytic therapy increased from 70% to 78.1% (P < 0.01) as median door-to-needle times fell significantly from 92 (60-145) to 68 (45-123) minutes (P < 0.01). The proportion of patients discharged on aspirin increased from 88.2% to 95.9% (P < 0.01), -blockers increased from 37.4% to 45.8% (P < 0.01), and angiotensin converting enzyme inhibitors increased from 12.4% to 35.7% (P < 0.01). Median hospital stay fell from 9 (7-11) to 6 (5-9) days (P < 0.0001). Although the severity of infarction declined, judged by reductions in the frequency of Q-wave development from 78.1% to 73.9% (P = 0.01) and peak CK from 1250 (569-2085) to 1004 (511-1722) IU/l, survival (95% confidence intervals) for the early and late cohorts did not change significantly either at 30 days [0.86 (0.83-0.88) vs. 0.85 (0.83-0.88)] or at 1 year [0.79 (0.76-0.81) vs 0.78 (0.76-0.81)].

Conclusion The decade from 1988-1997 saw significant changes in the demographic characteristics and risk factor profiles of patients with acute myocardial infarction admitted for coronary care. We observed trends towards increasingly aggressive antithrombotic treatment and early discharge policies, with more patients being prescribed drugs for secondary prevention. The combined effects of these complex changes on the outcome of infarction defy simple analysis and there was no palpable change in short-and longer-term prognosis.