Heart Failure Still a Problem but Less of a Burden on Acute MI Patients
Heart failure has become a less frequent complicating factor for acute MI over time and related mortality has declined, but it remains associated with worse short- and long-term outcomes. The findings, from a Swedish registry, were published in the March 2015 issue of JACC: Heart Failure.
Although the gains are encouraging, the continued negative impact on outcomes “can’t be ignored, warranting early identification of patients with [heart failure] for initiation of effective treatment strategies and closer follow-up to prevent adverse outcomes,” Liyew Desta, MD, of the Danderyd University Hospital (Stockholm, Sweden), told TCTMD in an email.
“Simple clinical findings, such as pulmonary rales (Killip classification), have a huge role in the risk stratification of patients who could be targets of specific therapies and follow-up strategies, underscoring the importance of meticulous evaluation,” he added.
Dr. Desta and colleagues looked at data from the SWEDEHEART/RIKS-HIA registry on 199,851 acute MI patients admitted to Swedish coronary care units from 1996 to 2008. During the study period, there were increases in mean age; the proportion of women; and rates of diabetes, current smoking, and hypertension and decreases in rates of prior histories of acute MI and congestive heart failure.
Heart failure—defined as the presence of pulmonary rales and use of continuous positive airway pressure (CPAP) or IV diuretics or inotropic drugs, with severity assessed by the Killip classification—complicated fewer admissions over time, with the rate falling from 46% in 1996-1997 to 28% in 2008 (P < .001). The declines were evident across age groups, with greater reductions seen in patients with STEMI and left bundle branch block than in those with NSTEMI. There were corresponding drops in use of CPAP and IV diuretics and inotropic drugs.
The proportion of heart failure patients with an ejection fraction of 50% or higher (normal) increased while that of patients with an ejection fraction under 40% decreased.
Over time, use of evidence-based therapies improved, with increasing use of PCI and various discharge medications, including aspirin, clopidogrel, beta-blockers, statins, and ACE inhibitors or angiotensin II receptor blockers.
All of these shifts translated into better outcomes for patients who had heart failure as the study progressed. Mortality rates dropped in the hospital (19% to 13%), at 30 days (23% to 17%), and at 1 year (36% to 31%; P < .001 for trend). After multivariate adjustment, the odds of 1-year mortality declined among patients with clinical heart failure over time (OR per 2 calendar years 0.93; 95% CI 0.92-0.94).
Nevertheless, the presence of heart failure in and of itself put patients at twice the risk of mortality (adjusted HR 2.09; 95% CI 2.06-2.13).
Better Treatment Likely Behind Heart Failure Decline
One possible reason that heart failure is seen less frequently in patients with acute MI is that smaller infarcts are being detected, according to the authors.
An acute MI diagnosis based on “increasingly sensitive serial biomarkers has substantially increased the detection of [acute MI] cases, counteracting the actual declining rates of [the condition],” they write. “Smaller [acute MIs] that could have been missed with previous criteria are detected with the new criteria, which in turn could contribute to a reduced risk for subsequent [heart failure], as [heart failure] is related to infarct size.”
They note, however, that the reduction in heart failure did not change dramatically when the more sensitive definition of acute MI was introduced.
“We rather saw a smooth progressive decline, suggesting other explanations, such as more frequent use of effective evidence-based treatments and changes in the burden of risk factors,” they write. “The greater decrease of [heart failure] observed in patients with STEMIs compared with those with NSTEMIs also argues against the suggestion that an overall decline in [heart failure] incidence is merely a reflection of the detection of smaller infarcts.”
Better care—including “the rapid and effective utilization of invasive treatment strategies in patients with acute MIs, better medications for [heart failure], as well as improved secondary prevention measures of ischemic heart disease”—likely also explains the improving outcomes among patients with heart failure, Dr. Desta and colleagues say.
Clyde W. Yancy, MD, of Northwestern University Feinberg School of Medicine, agreed in a telephone interview with TCTMD.
“Overall, I think it would be pretty hard to not recognize that there have been some real gains in the care of patients with acute MI, and in addition to a lesser risk of death, a shorter length of stay, and a better quality of life—because we’ve preserved muscle—there’s less heart failure,” he said, noting that the findings from Sweden are likely applicable to other developed countries, including the United States. “Everything that we’ve been doing up until now has worked.”
He said that the situation is probably even better now than in 2008 but added that heart failure continues to be a problem in patients with acute MI. “So it speaks to prompt early therapy for ACS and then for heart failure… [and] it shows you that we can prevent a disease that has still significant consequences. Maybe the best way to do that is to continue to focus even further upstream and prevent the initial event from occurring,” Dr. Yancy suggested.
Justin A. Ezekowitz, MBBCh, MSc, of the University of Alberta (Edmonton, Canada), echoed the belief that general improvements in ACS care—including better ambulance systems, earlier identification of symptoms, and earlier use of thrombolysis or PCI—were the main reasons for the observed trends. “Really the implications are that with a better system, people will do better,” he told TCTMD in a telephone interview.
He said it is important for clinicians to recognize the signs and symptoms of heart failure during an MI. Heart failure is “a very important marker for somebody who’s at higher risk than those who do not have that, so clinicians should pay attention to that and act accordingly,” Dr. Ezekowitz said. “Sometimes that’s going to be [using] newer or different therapies and implementing other guideline-based medical therapy. And sometimes it’s going to mean more or greater surveillance in hospital but also importantly, after hospital; those patients are going to be the ones where you really want to do earlier and much closer surveillance after discharge.”
The authors acknowledge that the registry data could not be used to distinguish between patients who had clinical heart failure prior to admission and those who developed it during the hospital stay. Also, there was no information on aldosterone antagonist use.
An additional limitation, note Anuradha Lala, MD, and Judith S. Hochman, MD, of New York University School of Medicine (New York, NY), in an accompanying editorial, is that “the definition of [heart failure] can be complicated, and cases may have been missed by not assessing other commonly used signs reflecting congestion, such as elevated jugular venous pressure, orthopnea, and natriuretic peptide levels.”
Even so, the study shows that “the continued use of the Killip classification helps identify a high-risk group for whom specific therapies need to be targeted,” the editorialists say. “Patients with [heart failure] symptoms after MI (ie, Killip class II or greater) likely require triage to a higher level of care while in the hospital, meticulous attention to guideline-directed medical therapy, and closer postdischarge follow-up to prevent adverse outcomes.”
1. Desta L, Jernberg T, Löfman I, et al. Incidence, temporal trends, and prognostic impact of heart failure complicating acute myocardial infarction: the SWEDEHEART registry (Swedish Web-System for Enhancement and Development of Evidence-Based Care in Heart Disease Evaluated According to Recommended Therapies): a study of 199,851 patients admitted with index acute myocardial infarctions, 1996 to 2008. J Am Coll Cardiol HF. 2015;3:234-242.
2. Lala A, Hochman JS. Standing the test of time [editorial]. J Am Coll Cardiol HF. 2015;3:243-244.
- Dr. Desta reports receiving grant funding from the board of the Swedish Heart Failure Registry.
- Drs. Ezekowitz, Hochman, Lala, and Yancy report no relevant conflicts of interest.