Since COVID-19 Onset, Admissions for MI Are Down, Mortality Rates Are Up

Ted Bosworth

August 14, 2020

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A substantial decrease in hospital admissions for acute MI was accompanied by a rise in mortality, particularly for ST-segment elevation MI (STEMI), following the onset of the COVID-19 pandemic, according to a cross-sectional retrospective study.

Although it can't be confirmed from these results that the observed increase in in-hospital acute MI (AMI) mortality are related to delays in seeking treatment, this is a reasonable working hypothesis until more is known, commented Harlan Krumholz, MD, who was not involved in the study.

The analysis, derived from data collected at 49 centers in a hospital system spread across six states, supports previous reports that patients with AMI were avoiding hospitalization, according to the investigators, who were led by Tyler J. Gluckman, MD, medical director of the Center for Cardiovascular Analytics, Providence Heart Institute, Portland, Ore.

When compared with a nearly 14-month period that preceded the COVID-19 pandemic, the rate of AMI-associated hospitalization fell by 19 cases per week (95% confidence interval, –29.0 to –9.0 cases) in the early COVID-19 period, which was defined by the investigators as spanning from Feb. 23, 2020 to March 28, 2020.

The case rate per week then increased by 10.5 (95% CI, 4.6-16.5 cases) in a subsequent 8-week period spanning between March 29, 2020, and May 16, 2020. Although a substantial increase from the early COVID-19 period, the case rate remained below the baseline established before COVID-19.

The analysis looked at 15,244 AMI hospitalizations among 14,724 patients treated in the Providence St. Joseph Hospital System, which has facilities in Alaska, California, Montana, Oregon, Texas, and Washington. The 1,915 AMI cases captured from Feb. 23, 2020, represented 13% of the total.

Differences in Mortality, Patients, Treatment

In the early period, the ratio of observed-to-expected (O/E) mortality relative to the pre–COVID-19 baseline increased by 27% (odds ratio, 1.27; 95% CI, 1.07-1.48). When STEMI was analyzed separately, the O/E mortality was nearly double that of the baseline period (OR, 1.96; 95% CI, 1.22-2.70). In the latter post–COVID-19 period of observation, the overall increase in AMI-associated mortality on the basis of an O/E ratio was no longer significant relative to the baseline period (OR, 1.23; 95% CI, 0.98-1.47). However, the relative increase in STEMI-associated mortality on an O/E basis was even greater (OR, 2.40; 95% CI, 1.65-3.16) in the second COVID-19 period analyzed. Even after risk adjustment, the OR for STEMI mortality remained significantly elevated relative to baseline (1.52; 95% CI, 1.02-2.26).

The differences in AMI patients treated before the onset of the COVID-19 pandemic and those treated afterwards might be relevant, according to the investigators. Specifically, patients hospitalized after Feb. 23, 2020 were 1-3 years younger (P < .001) depending on type of AMI, and more likely to be Asian (P = .01).

The length of stay was 6 hours shorter in the early COVID-19 period and 7 hours shorter in the latter period relative to baseline, but an analysis of treatment approaches to non-STEMI and STEMI during the COVID-19 pandemic were not found to be significantly different from baseline.

Prior to the COVID-19 pandemic, 79% of STEMI patients and 77% of non-STEMI patients were discharged home, which was significantly lower than in the early COVID-19 period, when 83% (P = .02) of STEMI and 81% (P = .006) of non-STEMI patients were discharged home. In the latter period, discharge to home care was also significantly higher than in the baseline period.

More Than Fear of COVID-19?

One theory to account for the reduction in AMI hospitalizations and the increase in AMI-related mortality is the possibility that patients were slow to seek care at acute care hospitals because of concern about COVID-19 infection, according to Dr. Gluckman and coinvestigators.

"Given the time-sensitive nature of STEMI, any delay by patients, emergency medical services, the emergency department, or cardiac catheterization laboratory may have played a role," they suggested.

In an interview, Dr. Gluckman said that further effort to identify the reasons for the increased AMI-related mortality is planned. Pulling data from the electronic medical records of the patients included in this retrospective analysis might be a "challenge," but Dr. Gluckman reported that he and his coinvestigators plan to look at a different set of registry data that might provide information on sources of delay, particularly in the STEMI population.

"This includes looking at a number of time factors, such as symptom onset to first medical contact, first medical contact to device, and door-in-door-out times," Dr. Gluckman said. The goal is to "better understand if delays [in treatment] occurred during the pandemic and, if so, how they may have contributed to increases in risk adjusted mortality."

Dr. Krumholz, director of the Yale Center for Outcomes Research and Evaluation, New Haven, Conn., called this study a "useful" confirmation of changes in AMI-related care with the onset of the COVID-19 pandemic. As reported anecdotally, the study "indicates marked decreases in hospitalizations of patients with AMI even in areas that were not experiencing big outbreaks but did have some restrictions to limit spread," he noted.

More data gathered by other centers might provide information about what it all means.

"There remain so many questions about what happened and what consequences accrued," Dr. Krumholz observed. "In the meantime, we need to continue to send the message that people with symptoms that suggest a heart attack need to rapidly seek care."

The investigators reported having no financial conflicts of interest.

SOURCE: Gluckman TJ et al. JAMA Cardiol. 2020 Aug 7. doi: 10.1001/jamacardio.2020.3629.

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