Patients who do not receive care for non–ST-segment elevation myocardial infarction (NSTEMI) within 24 hours have a substantially increased risk of mortality 3 years later when compared with those receiving earlier intervention, according to a population-based study evaluating more than 6,000 patients.
The characteristics of patients receiving NSTEMI care more than 24 hours after symptom onset were different from those treated earlier, but understanding these differences might provide clues for improved pathways to care, according to the investigators of this study, published in the Journal of the American College of Cardiology.
In a study of 6,544 NSTEMI patients in the Korea Acute Myocardial Infarction Registry, 1,827 (27%) were evaluated and treated 24 hours or more after symptom onset. When compared with the group with a shorter symptom-to-door time, outcomes at a median follow-up of 1,098 days were substantially worse.
Most importantly, this included a more than 50% absolute unadjusted increase in death from any cause (17.0% vs. 10.5%). On a 3-year adjusted multivariate hazard ratio, the increase was 35% (HR, 1.35; 95% confidence interval, 1.17-1.56; P < .001)
The absolute relative increase in cardiac death was similar in the delayed treatment group (10.8% vs. 6.4%) with a 37% increase in the 3-year multivariate adjustment (HR, 1.37; 95% CI 1.14-1.65; P < .001).
Delay raises composite adverse outcome >50%
On a composite of events that included mortality, recurrent MI, or hospitalization for heart failure, the rates climbed from 15.7% in the group treated within 24 hours to 23.3% (P < .001) when treatment was delayed. Heart failure, which was not significantly increased when evaluated separately, was not a major contributor to adverse outcomes, but those with delayed treatment did have more recurrent MIs (5.3% vs. 3.7%; P = .02).
Among a long list of differences between groups, those with delayed care had higher rates of atypical chest pain (25.1% vs. 14.8%; P < .001) and dyspnea (32.6% vs. 23.4%; P < .001). Expressed in odds ratios, they were also significantly more likely to be female (OR, 1.23), be aged 75 years or older (OR, 1.44), have diabetes (OR, 1.31), and to arrive at the hospital without aid from emergency medical services (OR, 3.44).
NSTEMI patients with delayed symptom-to-door time were also less likely to have hypertension (54.8% vs. 59.1%; P < .001), chronic kidney disease (20.8% vs. 25.5%), or a family history of cardiovascular disease (4.7% vs. 7.4%; P < .001). They were more likely to have left main and multivessel disease (57.1% vs. 50.5%; P < .001).
The value of early treatment has already been demonstrated for STEMI, which is reflected in guidelines, most of which now emphasize minimizing the door-to-balloon angioplasty time in order to more rapidly restore perfusion, thereby preserving more functional cardiac tissue. This study suggests that benefit from early intervention is also true of NSTEMI.
Reducing prehospital delay in care “should be emphasized as a crucial factor that increases the risk of all-cause mortality in NSTEMI patients,” reported the authors, led by Jung-Joon Cha, MD, PhD, division of cardiology, Korea University Anam Hospital, Seoul.