Since the inception of cardiac care units (CCUs), admitting patients with ST elevation myocardial infarction (STEMI) to CCU and intensive care unit (ICU) settings has been the default (1–3). CCUs were lifesaving for these patients, significantly reducing mortality from STEMI complications (3, 4). Due to an evolution in revascularization technology, strategies, and abilities (5), STEMI mortality has decreased significantly to the point where some STEMI patients are considered low risk for major adverse cardiac events (MACE) and other traditional complications from STEMI (6, 7). However, the practice of admitting all STEMI patients to ICUs remains routine (1, 2), even for the growing number of these patients who are neither high risk nor critically ill (8).

As the acuity of the STEMI population has changed, so has the patient population in CCUs. Modern CCUs have transformed into Cardiac Intensive Care Units (CICUs) that now accommodate patients with higher acuity and increasing medical complexity, including sepsis, acute kidney injury, and respiratory failure (9, 10). As a result, there is a growing demand for ICU beds and critical care resources, making it imperative to reassess how these units are being utilized.

Given the improvement in STEMI outcomes, recent studies have focused on deescalating post STEMI care and have revealed over 82% of STEMI patients do not require critical care interventions (8), and many can be safely discharged within 48-hours post-revascularization (11). However, without a STEMI-specific risk stratification model, especially without an understanding of the timing of critical care needs and interventions and specific angiographic data in this population, ICU resources for these patients continue to be overused (8), driving up healthcare costs (12) without clear benefit to mortality or outcomes (13).

Our study seeks to identify timing of critical care needs and expand on clinical predictors of critical care needs in STEMI patients in order to improve triage decisions and ICU resource utilization in these patients.

Among our study population, 141 out of 758 patients (18.6%) had a critical care need as described previously and 757 were admitted to a CICU (one died prior to admission). Of the 141 patients with critical care needs, most (71%) had critical care resources initiated prior to CICU admission: 22 (15.6%) in the ED, 78 (55.3%) in the cardiac catheterization lab, 39 (27.7%) in the CICU/other ICU, and 2 (1.4%) on the inpatient units within 24 h of ICU downgrade (Figure 1). In addition, those with a critical care need in the ED were more likely to die prior to discharge (OR 8.76, 2.7–24.6, p < 0.001), while those with a critical care need that started in the cardiac catheterization lab or CICU were not at significantly increased risk for mortality (Figure 1). Those without a critical care need (n = 617) had a significantly less chance of dying prior to discharge [OR 0.17 (0.1–0.4), p < 0.0001] (Figure 1).

We compared baseline demographics and clinical characteristics between the two cohorts (Table 1). A univariable logistic regression analysis was utilized to compare the effects of baseline clinical characteristics and revascularization on critical care needs. We found that patients with Medicaid insurance were significantly more likely (OR 1.75, 1.2–2.5, p = 0.004) to have a critical care need while those with private insurance were less likely (OR 0.61, 0.4–0.9. p = 0.013) to have a critical care need (Figure 2). Patients who were African American (OR 0.49, 0.22–0.96, p = 0.04) and those with elevated BMI ≥ 30 (OR 0.43, 0.27–0.66, p = 0.002) had reduced rates of critical care need. We also found that history of coronary artery disease (OR 1.8, 1.1–2.7, p = 0.014), congestive heart failure (OR 4.6, 1.9–11.5, p = 0.001), chronic kidney disease (OR 3.21, 1.5–6.6, p = 0.003) and atrial fibrillation or flutter (OR 3.4, 1.4–8.3, p = 0.009) were more common in the critical care needs group (Figure 2).

The majority of critical (>70%) stenoses in culprit coronary arteries were revascularized, including 100% of Left Main (LM), 96.4% of Left Anterior Descending (LAD), 91.3% of Left Circumflex (LCX), and 96.8% of Right Coronary Artery (RCA). However, in the small subset of unrevascularized culprit vessels, the need for critical care was significantly higher. Specifically, a critical stenosis in an unrevascularized LAD had significantly more critical care need (OR 11.6, 95% CI 3.4–53.5, p = 0.0003), as was an unrevascularized LCX (OR 7.4, 95% CI 1.3–57.7, p = 0.03). Multivessel disease had significantly increased critical care need (OR 2.07, 95% CI 1.4–3.0, p < 0.001), as was an increasing number of critically diseased coronary vessels (OR 1.9, 95% CI 1.5–2.5, p < 0.001) (Figure 2). Lastly, patients requiring critical care had significantly higher mortality compared to those who did not (OR 5.9, 95% CI 2.8–12.8, p < 0.0001) (Figure 2).

We also utilized a multivariable logistic regression statistical analysis to compare variables across groups with and without a critical care need (Figure 3). Factors associated with critical care need included history of chronic kidney disease (OR 4.3, 95% CI 0.96–17.5, p = 0.045), having a STEMI in the COVID era (OR 2.7, 95% CI 1.5–5.1, p = 0.002), and a Modified Shock Index (MSI) ≥ 0.93 on admission (OR 4.04, 95% CI 2.04–8.08, p < 0.001). Higher ejection fraction was protective (OR 0.97 per 1% increase, 95% CI 0.94–0.99, p = 0.007). Catheterization data showed that a critical stenosis (>70%) in a proximal culprit artery was not associated with critical care need, possibly because these lesions were routinely revascularized. In contrast, multivessel disease was significantly associated with critical care need (OR 3.06, 95% CI 1.6–5.8, p < 0.001).

The major findings of this study are fourfold. One, despite the entire STEMI cohort being admitted to the ICU as part of our hospital's protocol, only 18.6% of these patients were critically ill. Second, the majority of these ICU needs arose before ICU admission. Three, STEMI patients with non-revascularized proximal LAD or LCx lesions and multivessel lesions had increased burden of critical care needs, while successful PCI of culprit lesions mitigated ICU needs regardless of the culprit vessel. Finally, our study also found that chronic kidney disease and low ejection fraction were independently associated with critical care needs in this cohort.

Previous studies have assessed the general risk of mortality in STEMI patients (15–17) and have noted the over-triage of these patients to intensive care settings in the absence of critical illness (22, 23). Our study validates this data but also provides novel insights not previously reported in this setting by examining granular data that is used in real world settings but not available in larger registries, such as the timing of critical care needs for this cohort and also culprit lesion involvement. We found that less than twenty percent of our STEMI patients had critical care needs. This percentage was consistent with larger, multi-centered and registry-based studies (22, 24). However, our study differs and is unique from these larger studies in that it specifies that most critical care needs in this cohort occur before ICU admission, occurring mainly in the catheterization lab. Notably, patients who required critical care interventions in the ED were significantly more likely to die prior to discharge, which likely reflects those presenting in extremis or with very high initial acuity. This implies that the majority of patients who do not require critical care interventions prior to or during revascularization for a STEMI are unlikely to develop a need for them afterwards. Therefore, STEMI patients who have had an uncomplicated hospital course up until the time of admission have a low risk of adverse events if admitted to a non-ICU setting or if discharged from the hospital within 24–48 h. These findings help build on the current literature by giving more granular detail to the overall rate of critical illness in STEMI patients, which were generally cited by larger, registry-based studies. They also challenge the current standard of care and guideline recommendation (25) where the majority of STEMI patients are admitted to the CICU even in the absence of a critical care need (1–3). These results further support the growing paradigm that low-risk STEMI patients post revascularization can be triaged not only to telemetry floors (26) but even potentially discharged from the hospital (17).

We are also the first to identify the impact of specific coronary anatomy on critical care needs in STEMI patients. We demonstrated that patients with non-revascularized proximal LAD or LCX lesions and multivessel lesions are associated with an increased burden of critical care needs. Conversely, successful PCI of culprit lesions mitigated ICU needs regardless of the culprit vessel. This is notable in that many current risk stratification scores designed to identify STEMI patients at low risk for complications and MACE that may be eligible for early hospital discharge designate anterior wall infarct, even if revascularized, as contributing to a higher risk profile (6, 7, 27). Other studies have also cited the perceived increased risk in LAD revascularization, especially its proximal segment, perhaps due in part to the amount of myocardium it supplies and the fact that until recently, surgical intervention was the preferred method of revascularization (28–30). Our study did find that kidney disease and low ejection fraction were associated with critical care needs, consistent with other risk stratification studies (31, 32) that found these variables conferred higher risk in STEMI patients.

However, the risk factors for critical illness in STEMI patients identified in this study were not always consistent with all risk factors cited in the current literature for this population. This can be explained by the fact that these studies have not specifically examined the characteristics that carry higher or lower risk for critical care needs in STEMI patients. Current risk models, including PAMI-II, APACHE III, and Modified Zwolle risk scores focus primarily on mortality and complication risk to help determine suitability for early hospital discharge rather than critical care needs (15–17). These tools vary in their approach and may not fully address the complexities of patient needs in the acute setting or predict critical care requirements accurately. For example, while the Modified Shock Index was a strong predictor of critical care needs in our study and in prior literature (14), it lacks integration of critical angiographic and clinical parameters, limiting its applicability as a stand-alone triage model. Our findings suggest that incorporating clinical factors, hemodynamic data, and angiographic specifics into a risk score could significantly improve risk stratification and ICU resource allocation for STEMI patients. As multiple studies have shown that CICU stays and prolonged inpatient admissions for low-risk STEMI patients do not improve clinical outcomes and are not associated with improved patient satisfaction (33, 34) but do contribute to rising hospitalization costs (8, 12, 13), finding an accurate method to determine which cohort of STEMI patients truly need ICU admission is essential.

All patients in our cohort were admitted to the CICU regardless of insurance status, as per our institutional STEMI protocol. Therefore, these differences may reflect underlying socioeconomic and comorbidity differences, not differences in ICU access. The association of Medicaid insurance with greater critical care needs likely reflects underlying socioeconomic disparities, comorbidity burden, and barriers to longitudinal care. These findings underscore the need for health system and policy-level strategies to address disparities in outcomes for STEMI patients.

This study has several limitations. It is a retrospective, single-center design, which may limit generalizability and introduce confounding, and therefore should be considered hypothesis-generating. We defined the post-COVID era as STEMI admissions after March 2020 without confirming individual infection status; thus, higher critical care use may reflect pandemic-related factors rather than COVID illness itself. The generalizability of this variable to non-pandemic contexts is limited. We did not have precise door-to-balloon times for transferred patients, which restricted assessment of treatment delays. However, the higher critical care needs in unrevascularized LAD and LCx lesions emphasize the importance of timely and complete reperfusion. Culprit vessel location was not predictive once successful PCI occurred. Although adequately powered for the primary analysis, the study may have been underpowered to detect associations in certain subgroups, such as non-revascularized patients. We defined “critical care need” by resource utilization, which overlaps with therapies used in cardiogenic shock, suggesting that our findings may have relevance for early triage in this high-risk population. Finally, only a small number of patients underwent CABG evaluation, and while these cases typically require critical care, their low frequency meant they likely had little influence on the overall findings.

Future directions include expanding this work to a multicenter registry or national database, which would provide greater statistical power, enhance external validity, and allow for cost-effectiveness analyses. This represents a logical next step that we are actively exploring within our network.

Most STEMI patients requiring critical care had already decompensated before CICU admission, and clinical factors such as chronic kidney disease, elevated Modified Shock Index, and multivessel lesions helped identify those at higher risk. Our findings challenge routine ICU admission for all STEMI patients and highlight the need for refined risk stratification to optimize resource utilization and improve patient outcomes.