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Growing implementation of evidence-based strategies for treating ST-segment elevation myocardial infarction (STEMI) in Sweden over a 12-year period was associated with a substantial and sustained reduction in mortality, according to registry data published in the April 27, 2011, issue of the Journal of the American Medical Association.

Investigators led by Tomas Jernberg, MD, PhD, of Karolinska University Hospital (Stockholm, Sweden), analyzed data on 61,237 consecutive patients with a first-time diagnosis of STEMI between 1996 and 2007 who were enrolled in the national Register of Information and Knowledge about Swedish Heart Intensive Care Admission (RIKS-HIA).

RIKS-HIA prospectively collects information on baseline characteristics, ECG findings, interventions, and in-hospital complications as well as discharge medications and diagnoses. This information was correlated with patients’ medical history from the National Patient Registry and mortality data from the National Death Registry.

Practice Improves Over Time

Evidence-based hospital treatments including the use of reperfusion (thrombolysis or primary PCI), specifically primary PCI, any revascularization (primary PCI or CABG), and glycoprotein IIb/IIIa inhibitors, all increased significantly over the study period. As use of primary PCI grew, in-hospital thrombolysis declined (table 1).  

 Table 1. Prevalence of Evidence-Based Treatments

 
However, hospitals differed widely in their rates of adoption, and for reperfusion and primary PCI that variation did not change over time.

Interestingly, the crude median time from symptom onset to PCI increased from 185 minutes at study outset to 216 minutes in 2000 to 2001 before falling back to 203 minutes in 2006 to 2007. On the other hand, the crude median time from symptom onset to thrombolysis continuously decreased from 188 minutes to 150 minutes over the study period.

Among in-hospital and discharge medications proven to reduce mortality and morbidity, use of aspirin increased before falling back slightly below baseline, while by the end of the study clopidogrel was being prescribed to more than 4 out of 5 STEMI patients. In addition, use of statins, beta blockers, and ACE inhibitors or angiotensin receptor blockers (ARBs) rose steadily (table 2).

Table 2. Prevalence of Evidenced-Based Medications

 
Overall, the estimated proportion of patients experiencing in-hospital complications declined between 1996 to 1997 and 2006 to 2007 (P for trend < 0.001 for all endpoints). These included:

• New MI: From 4% to 1%
• Need for advanced CPR: From 8% to 6%
• Atrioventricular block: From 6% to 3%
• New atrial fibrillation: From 11% to 5%

The only exception was severe bleeding, which increased from 1% to 2% of patients (P for trend < 0.001)—probably due to greater use of interventions and intensified antithrombotic therapy, the authors suggested.

Survival Increased Early and Late

Most importantly, growing use of evidence-based treatments was associated with improvements in survival (P for trend < 0.001 for all endpoints). Over the study period, estimated mortality decreased:

• In-hospital, from 12.5% to 7.2%
• At 30 days, from 15.0% to 8.6%
• At 1 year, from 21.0% to 13.3%

Most of the mortality reduction occurred within the first 30 days, although those who survived for that period experienced another 1.3% reduction out to 1 year. Older patients benefited more, with those over 74 years gaining an absolute reduction of 11% and those between 65 and 74 an 8% reduction, while patients younger than 65 had a 3% reduction. Moreover, in the 12-year analysis, the mortality decrease was sustained over time. STEMI patients in 2007 could expect an extra 2.7 years of life compared with their counterparts treated at the study outset.

The authors acknowledge that because the study is observational, it cannot prove that expanded use of guideline-based treatments actually caused the decline in complications and mortality. Moreover, some evidence (eg, the decreasing proportion of patients with a history of prior MI) suggests that patients treated near the end of the study were somewhat lower risk than earlier patients. However, the investigators add, the mortality reduction held even after adjustment for baseline characteristics.

The US Experience

In an accompanying editorial, Debabrata Mukherjee, MD, of Texas Tech University Health Sciences Center (El Paso, TX), writes that in the United States the main impetus for implementing guideline-based STEMI care comes from the ACTION Registry-Get With The Guidelines program. He identifies 3 strategies that have been associated with “translating efficacy into effectiveness:”

• Involvement of all stakeholders
• Emphasis on standard orders and discharge tools that prompt clinicians to consider evidence-based therapies for every patient from admission to discharge
• Rapid or concurrent and continuous feedback to physicians on use of appropriate evidence-based therapies

“We’re seeing similar improvement in the use of these therapies in this country,” said Matthew T. Roe, MD, of Duke University Medical Center (Durham, NC), whose research has tracked trends in acute MI care in the United States. “But what we haven’t been able to do is make the linkage with long-term outcomes.”

Advantages of the Swedish System

“In Sweden [researchers] have an ideal situation,” Dr. Roe told TCTMD in a telephone interview. “Hospital participation [in the national registry] is mandatory and they can do longitudinal follow-up. In the United States, participation is voluntary and our registries are primarily in-hospital data, although we have done some linkage to Medicare data for older patients.” Another obstacle is that US patients must give permission to be followed, he said, adding that as a result “we only have a snapshot.”

Dr. Roe also pointed to several advantages Sweden holds in facilitating implementation of guideline-based treatments. “They have a very easy data entry system where clinicians input data as they take care of their patients. And they get real-time feedback [on whether their treatment measures up],” he reported. Moreover, their health care system is relatively small and well organized, he added.

Dr. Roe confirmed that progress in adoption of new treatments is typically gradual. “When a new therapy is recommended by practice guidelines, we’ve shown it takes a few years to really see a strong improvement in practice,” he said. “Part of that relates to who the champions [of the new therapies] are at the hospital and how involved they are with influencing their colleagues. Also, I think you’d see more rapid uptake at academic centers, although that’s not proven.

"Decision support tools are very important [in implementing guidelines treatments],” Dr. Roe continued. “As you’re taking care of patients, reminders pop up saying, Did you use a beta blocker? Did you use a statin? At the hospital level, [it is helpful] to get feedback on practice trends every quarter or two. That allows you to step back and say, We’re improving here but not there, so how are we going to change our approach?”

More Than Treatment, a New Approach 

In a telephone interview with TCTMD, Harlan M. Krumholz, MD, SM, of Yale University School of Medicine (New Haven, CT), said that in his view credit for the marked improvement in STEMI outcomes over the past decade goes beyond increased use of recommended treatments.

“What’s most striking is how differently we approach acute MI than we did just a decade or so ago,” he observed. “We have improved systems of care within hospitals.” Today, an entire culture of cooperation is devoted to goals like reducing door-to-balloon time, eliminating errors, and reducing infection, he noted.

Dr. Krumholz attributed higher long-term survival rates to a combination of revascularization, improved follow-up care, and greater attention to secondary prevention. In particular, “use of statins has made a big difference,” he said.

Dr. Roe concurred that “what happens to patients after discharge” is key, noting that the next stage of research should focus on reducing readmissions and repeat procedures by helping patients comply with medications and alter their lifestyle.

Meanwhile, Dr. Krumholz asserted that the current study “is proof of concept that just by changing the way we practice—even without breakthroughs in procedures or medications—we can make great strides.” 

Study Details

Over the 12-year observation period, patients’ median age decreased from 71 to 69 years, while the proportion of women held steady at about 35%. The prevalence of hypertension increased (from 29% to 39%) as did that of smoking (from 27% to 30%); the percentage of diabetics remained stable at about 19%. Previous MI decreased from 19% to 10%, and history of heart failure declined from 6% to 4%.

2. Mukherjee D. Implementation of evidence-based therapies for myocardial infarction and survival. JAMA. 2011;305:1710-1711.

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