Elderly STEMI Patients Face Poorer Outcomes After Primary PCI

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Older patients have higher complication and mortality rates within 90 days of primary percutaneous coronary intervention (PCI) for ST-segment elevation myocardial infarction (STEMI) than their younger counterparts, according to a paper published in the March 28, 2011, issue of the Archives of Internal Medicine.

However, the results should not in any way discourage clinicians from treating elderly STEMI patients, who stand to benefit from PCI, stressed interventionalists interviewed by TCTMD.

Christopher B. Granger, MD, of Duke University Medical Center (Durham, NC), and colleagues retrospectively analyzed outcomes for 5,745 high-risk STEMI patients enrolled in the APEX-AMI (Assessment of Pexelizumab in Acute Myocardial Infarction) trial from July 2004 to May 2006. Patients were stratified into 3 age groups: younger than 65 years (n = 3,410), 65 to 74 years (n = 1,358), and 75 years or older (n = 977). Nearly half (46.6%) of patients in the eldest group were at least 80 years old, and 12.9% were at least 85 years old.

Compared with younger patients, those who were at least 75 years old were more likely to have in-hospital electrical complications such as atrial or ventricular fibrillation and ventricular tachycardia as well as mechanical complications such as cardiac tamponade and acute mitral regurgitation. Other in-hospital clinical events including hypotension, recurrent ischemia, and bleeding also were more common in the oldest patients. Stroke occurred within 7 days of randomization in 0.4%, 1.1%, and 1.5% of the 3 groups, increasing with age (P < 0.001).

At 90 days, the co-primary outcomes of mortality and the composite of CHF, shock, and death also rose along with patient age (table 1).

Table 1. Outcomes by Age

Multivariable adjustment demonstrated age to be the strongest independent predictor of 90-day mortality (HR 2.07 per 10-year increase; 95% CI 1.84-2.33). Other factors linked to mortality were heart rate, serum creatinine level, ST-segment deviation, and high-risk inferior MI. Even after adjusting for these variables, age retained its powerful influence on mortality.

“Despite optimal mechanical reperfusion and high rates of adjunctive medical treatment, age remains the main predictor of 90-day mortality in STEMI patients treated with [primary] PCI,” the investigators conclude. “Efforts to attenuate this risk and understand reperfusion factors that increase age-associated outcomes are needed.”

Older STEMI patients derive poorer outcomes due to a number of factors, they note, including greater comorbidities, baseline hemodynamic status, CAD severity, post-procedural angiographic results, and heightened risk for greater complications. Moreover, there may be unmeasured confounders such as hemostatic reserve, frailty and preexisting disabilities.

Age Shows Wide Range of Influence

In the study, the proportion of women increased with age, representing 16.2%, 26.5%, and 42.4% of the 3 age groups, respectively. Patients aged 75 years and older were more likely to have hypertension, angina, prior CABG, CHF, and COPD; to experience left bundle branch block; and to present with higher Killip class than were younger patients. The time from symptom onset to randomization was slightly but significantly longer in conjunction with age, ranging from 2.7 hours in the youngest group to 3.1 hours in the oldest group. Older patients had lower prevalence of postprocedural TIMI grade 3 flow and less ST-segment resolution after treatment despite similar infarct size.

In-hospital medication use, including aspirin, thienopyridines, glycoprotein IIb/IIIa inhibitors, beta blockers, ACE inhibitors, and statins, was slightly lower among older patients. However, patients without contraindications were equally likely to be discharged on aspirin, beta blockers, ACE inhibitors, and statins, regardless of age.

‘Best-case Scenario’

In a telephone interview, Dr. Granger told TCTMD that the results are likely better than what would be obtained in routine clinical practice.

“Because this is from a clinical trial database, where the sickest patients tend to be excluded, this is probably better than the true rates in general practice. So this is the best-case scenario,” he noted, adding, “To put this in perspective, you hear people saying, ‘Well, now with modern treatment of heart attacks, mortality is 2% or something.’ That’s clearly not true if you look at high-risk groups, especially the elderly.”

Dr. Granger said that an “easy to remember statistic is that for every 10 years of age there’s a doubling of mortality.”

But the findings should not in any way discourage using primary PCI in this population, he stressed. “They’re the group that gets the greatest absolute benefit from those treatments that have been proven to improve outcome. . . . Even with the best treatment, their mortality is this high [but] without it, it would probably be twice as high.”

Jeffrey W. Moses, MD, of Weill Cornell Medical College (New York, NY), strongly agreed. “The net benefit of therapy and lives saved are always greater in the elderly. The higher mortality is against a background of higher untreated mortality,” he said.

Dr. Moses was unsurprised by the finding that poorer outcomes increased with age. “Older people are at high risk for everything,” Dr. Moses commented. “Perturbations in their system have more of an impact. You see higher stroke rates, higher heart failure. Their hearts may not be more damaged from MIs, but there’s less reserve in terms of tolerating disturbances. . . . It’s a different physiologic substrate.”

In an e-mail communication, David A. Cox, MD, of Lehigh Valley Hospital (Allentown, PA), told TCTMD that he felt the APEX-AMI findings mirror what is seen in clinical practice, with the caveat that it is difficult to capture all elderly patients that present with shock in a trial setting.

That being said, “[w]e all recognize in clinical practice elderly patients may have even higher mortality than that seen in APEX AMI. Understanding the mode of death in these patients is critical, as the great majority die even though a successful PCI was done,” he noted, praising the investigators for enrolling so many elderly patients.

How to Optimize Outcomes?

All 3 physicians emphasized that there are opportunities to further reduce mortality when performing primary PCI in elderly STEMI patients. “Usually, these days what we do is go back to the basics. Our biggest opportunity to improve care is to apply what we already know,” Dr. Granger noted.

Dr. Cox also offered numerous suggestions for how to improve outcomes.

“Obviously, patient selection plays a large part in improving this, but that will take a joint effort between clinically savvy ER physicians and PCI doctors to be sure we don't take elderly patients to the cath lab inappropriately,” he said, adding that it is important to limit contrast media use and to adjust doses of antithrombotics and glycoprotein IIb/IIIa inhibitors. “It's a huge challenge but an important one, and each of us as interventionalists need to pay more attention to following these patients after the procedure is done to be sure medical regimens are followed. Too often, aspirin or clopidogrel are held for a few days in this age group because of nuisance bleeding and that can be disastrous.”

Dr. Moses went a step further. “Once you implement all the guideline-based therapy, then it’s time to get back to the science. People think that just by adherence to protocols that people are going to survive,” he commented, proposing that crucial knowledge may be gained by asking why elderly patients are different. “Are there specific therapies for these high risk patients that should be employed? We don’t have them yet. We’ve been exploring them, in terms of infarct size, dealing with ventricular stiffness, maybe different pharmacologic regimens for stroke prevention.”

In the current study, “patients had excellent care by all conventional metrics in terms of door-to- balloon time, pharmacotherapy, etc, and yet they still had a very high frequency of major adverse events. So it shows there’s obviously still a lot of science to be done,” Dr. Moses said.

Dr. Granger pointed out that, much like in previous studies, his paper also found elderly patients were less likely than younger patients to receive basic evidence-based care, perhaps because physicians are risk averse and worried that some therapies may have unanticipated negative consequences.

“This reinforces the fact that we need to get these patients treated quickly with reperfusion therapy, ideally primary PCI, and that we need to be diligent about making sure they get all of the proven effective treatments,” he said, adding that another important message from the paper is that elderly patients should be included in trials testing new therapies because they are very high risk and represent an unmet clinical need.

 

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Source:
Gharacholou SM, Lopes RD, Alexander KP, et al. Age and outcomes in ST-segment elevation myocardial infarction treated with primary percutaneous coronary intervention: Findings from the APEX-AMI trial. Arch Intern Med. 2011;171:559-567.

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