Shock’s Added Risk in Acute MI Restricted to the First Few Months After Discharge

For patients who survive acute MI, cardiogenic shock raises the risk of death and/or rehospitalization for the first year after discharge, researchers report in the February 23 issue of the Journal of the American College of Cardiology. But that risk seems to be clustered within the first 60 days, after which patients seem to fare similarly whether or not they experienced shock.

Much of the research on acute MI focuses on more immediate outcomes like in-hospital mortality and 30-day readmission, lead author Rashmee U. Shah, MD, of the University of Utah (Salt Lake City, UT), told TCTMD. “But for the patient, the journey goes on. When they leave the hospital, they’re still dealing with what happened.”

Having uncovered the pattern of early risk in shock patients, it is now important to try to better understand how the condition negatively impacts outcomes and what can be done about it, she said.

Using the ACTION Registry-Get With The Guidelines database, Shah et al identified 112,668 survivors of acute MI aged 65 years or older who had been hospitalized between 2007 and 2012 and linked them with Medicare claims data. In all, 5% of patients in the cohort had cardiogenic shock during hospitalization. Compared with patients not in cardiogenic shock, those who had shock tended to be younger; less likely to have had prior MI, PCI, or CABG; and more likely to have reduced LVEF and to undergo diagnostic catheterization and revascularization.

The rate of death was higher among patients with cardiogenic shock at 60 days (9.6% vs 5.5%) and 1 year (22.4% vs 16.7%), as was the combined rate of all-cause hospitalization or death (33.9% vs 24.9% and 59.1% vs 52.3%, respectively).

After adjustment, however, cardiogenic shock only carried added risk within the first 60 days after the initial hospital stay for both death and death/all-cause rehospitalization. When narrowing the scope of the composite to include only heart–failure-related hospitalization—which accounted for 23% of return visits—the increased risk of cardiogenic shock also was restricted mainly to the first 60 days, with a slight elevation in risk continuing through 1 year.

This time-dependent distribution of risk was seen for both STEMI and NSTEMI patients.

Shock Patients Still Vulnerable Despite Gains in Care

Adnan Kastrati, MD, of Deutsches Herzzentrum (Munich, Germany), and colleagues point out in an accompanying editorial that the study offers no details on the causes of mortality or the nuances of treatments patients received during hospitalization. That being said, it “adds to our understanding of the risk trajectory of patients with AMI and cardiogenic shock,” they write.

Commenting on the study for TCTMD, Akshay Bagai, MD, MHS, of St. Michael’s Hospital (Toronto, Canada), said that the current results represent a “natural extension” of what he and fellow researchers found with NSTEMI patients using older data from the CRUSADE trial. Patients in that study were treated between 2003 and 2006, whereas Shah et al focused their sights on 2007 to 2012.

Care of acute MI patients with shock has evolved a lot over those years, Bagai noted. “In the last decade or so, we have become much more aggressive with revascularization of shock patients,” he said. Not only do patients have earlier and greater access to the cath lab but newer antiplatelet drugs have improved outcomes and supportive devices are in wider use. ICUs have also become more skilled at handling these very sick patients.

While there have been gains, it’s important to remember that in-hospital mortality for shock patients “remains very high,” he said, pointing out that this study only looked at survivors.

Many of the factors influencing mortality risk for these patients—such as older age, later presentation, and presence of comorbidities—are unmodifiable. Even so, much can be done to improve outcomes, Bagai stressed. “We can certainly do better when they do come into hospital, early on,” he said, in terms of offering revascularization quickly and using supportive devices as appropriate.

Look Beyond the Heart

According to the editorialists, the finding that fewer than one-quarter of rehospitalizations were related to heart failure “should prompt us to focus more on optimization of treatment of noncardiac conditions during the in-hospital and early-discharge periods in patients with AMI complicated by cardiogenic shock.”

Bagai agreed, saying that “absolutely” more attention should be paid to what goes on beyond the heart.

Additionally, “it’s important to recognize as a medical community that these patients are still at high risk once they leave the hospital,” he advised. Key ingredients to patients having a successful transition from hospital to their destination—whether home or rehab or a nursing care facility—include “making sure they get access to their family doctors and their cardiologists [for] follow-up very early after discharge [and ensuring] that they are not undertreated from a medication point of view,” he commented.

Patients hospitalized for acute MI may, in general, fall prey to “post-hospital syndrome,” Shah suggested. While treated in the ICU, “they’re essentially bed bound for a good amount of time, their nutritional status drops, their physical ability drops, and when they leave the hospital, they haven’t fully recovered from the hospitalization.

“But specifically for cardiogenic shock patients, because the heart muscle had become so weak—it’s not pumping blood to the whole body—this can have effects on other organs,” she continued. “So, maybe their kidneys aren’t working as well, maybe their cognition is not as good as it used to be.” In fact, impaired kidney function is a reason why patients with shock may be less likely to receive recommended medical therapies like ACE inhibitors, Shah suggested.

As to why the added risk carried by shock eventually dissipates, Bagai credited “survival of the fittest.” This selection bias means that “if you do die within the first 60 days you’re obviously a sicker person, and if you do make it to 60 days, you’ve shown that you can survive,” he said. “Once you’ve shown you’re a survivor, your outcomes are just based on other things outside of the shock, whether it’s that you’re old or have kidney disease, and then [the mortality risk] becomes just like the general population.”

Shah cautioned that, while the study provides valuable prognostic information, it should not be used as a justification for more intensive care that fails to take patient preference into account. “Our inclination, as cardiologists and interventionalists is to say, ‘What other life-saving interventions can I provide here to help these patients?’ Which is great. That’s our job and we can do it, and we can do it well,” she said. “But we can’t forget that maybe that’s not necessarily what all patients want. . . . We have an obligation to equally and fairly discuss [all the options] with our patients, not just the life-saving ones but the symptom-focused ones [like hospice and palliative care] as well.”
 

Sources: 
1. Shah RU, de Lemos JA, Wang TW, et al. Post-hospital outcomes of patients with acute myocardial infarction with cardiogenic shock: findings from the NCDR. J Am Coll Cardiol. 2016:67:739-747.
2. Kastrati A, Colleran R, Ndrepepa G. Cardiogenic shock: how long does the storm last [editorial]? J Am Coll Cardiol. 2016:67:748-750.