MI Less Frequent, Less Deadly Over 20 Years

Megan Brooks

March 25, 2019

There has been a "remarkable and progressive" decline in rates of acute myocardial infarction (AMI) in older adults over the past 20 years, and mortality after AMI is at a historic low, researchers report.

Between 1995 and 2014, the hospitalization rate for AMI fell 38% and the adjusted 30-day mortality rate declined 34%. In addition, there was a 2.7-year increase in the average age of patients presenting with AMI, which suggests progress in delaying the onset of AMI, the researchers say.

There has been "marked improvements in outcomes for AMI among the increasingly smaller number of people in the United States who experience it, representing a transition in the impact of this condition," they write.

The study was published online March 15 in JAMA Network Open.

Harlan M. Krumholz, MD, Yale School of Medicine, New Haven, Connecticut, and colleagues analyzed 20-year trends in outcomes for more than 4.3 million Medicare beneficiaries discharged with AMI between 1995 and 2014.

During the study period, the mean age of AMI patients increased from 76.9 to 78.2 years, the percentage of female patients declined from 49.5% to 46.1%, the percentage of white patients declined from 91.0% to 86.2%, and the percentage of black patients increased from 5.9% to 8.0%.

There were declines in AMI hospitalizations, 30-day mortality, 30-day all-cause readmissions, and 1-year recurrences.

Myocardial Infarction Outcomes: 1995 vs 2014
Outcome 1995 2014
Hospitalizations per 100,000 beneficiary-years 914 566
30-day mortality (%) 20.0 12.4
30-day all-cause readmissions (%) 21.0 15.3
1-year recurrent AMI (%) 7.1 5.1

The improvements were consistent across demographic groups defined by age, sex, race, and eligibility for Medicaid.

The Medicare inpatient payment per AMI discharge increased modestly over time (from $9282 to $11,031), but the total cost declined because the number of hospitalizations was "greatly" reduced, the researchers report.

National Efforts Paying Off

Improved outcomes likely reflect changes in AMI treatment over time, including increased rates of revascularization. The 30-day inpatient catheterization rate increased from 44.2% in 1995 to 59.9% in 2014, while inpatient percutaneous coronary intervention (PCI) rates jumped from 18.8% to 43.3%. Coronary artery bypass graft surgery rates declined from 14.4% to 10.2%.

Over the years, uptake of evidence-based strategies improved "dramatically," the researchers point out, and the speed of reperfusion therapy for ST-segment elevation AMI also improved, as did the use of PCI in general.

All of this occurred as a result of concerted efforts by the Centers for Medicare & Medicaid Services (CMS), the American College of Cardiology (ACC), the American Heart Association (AHA), and other national organizations, along with local hospitals and clinicians, to improve population risk and acute care. Lifestyle changes likely also contributed to the change in the rates of AMI, Krumholz and colleagues say.

This work extends the body of literature in several ways, they add. "Previous studies have reported some of these improvements, but not as comprehensively, or over a 20-year period or across the entire United States. As such, this work reveals novel insights about what has been achieved in reducing and mitigating AMI among Medicare beneficiaries," they write.

However, there was some heterogeneity in improvement over time. Of note, "priority health areas," previously identified by Krumholz and colleagues as lagging areas, saw little or no change in their 30-day mortality rates in the past 20 years. "These areas may particularly benefit from future improvement activities," they conclude.

The study had no specific funding. Krumholz reports personal fees from UnitedHealth, IBM Watson Health, Element Science, Aetna, Facebook, Arnold & Porter, and the Ben C Martin Law Firm; grants from the Centers for Medicare & Medicaid Services, Medtronic, Johnson & Johnson, and the US Food and Drug Administration; and serving as founder of the personal health information platform Hugo outside the submitted work.

JAMA Netw Open. Published March 15, 2019. Full text

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