Fujairah Hospital, United Arab Emirates.Background: Metabolic Syndrome (MetS) is a highly prevalent condition among patients with acute myocardial infarction (AMI) in the intensive care unit (ICU), yet its direct impact on in- hospital outcomes remain a subject of debate. This systematic review aims to synthesize the current evidence on the prevalence of MetS in critically ill AMI patients and its association with clinical severity and in-hospital mortality.

Methods: This is a systematic observational study. Data on patients’ demographics, clinical characteristics, and clinical outcomes were systematically extracted and synthesized. The study focused on prevalence rates, patient characteristics including age, gender, body mass index, waist circumference, and comorbidities, as well as in-hospital outcomes such as mortality, heart failure, and major adverse cardiovascular events.

Results: The prevalence of MetS in patients with AMI in the ICU setting is consistently high, ranging from 46% to 68.3% across different populations [1, 2]. Patients with MetS are more likely to be female and present with a higher body mass index (BMI), larger waist circumference, and a greater incidence of hypertension and diabetes. While some studies report no significant increase in all-cause in-hospital mortality, others indicate a significantly higher rate of cardiovascular mortality (P = .03) and an increased risk of complications such as congestive heart failure and recurrent myocardial ischemia [1, 3]. Specific components of MetS, notably hyperglycemia and a BMI ≥28 kg/m², have been identified as independent predictors of major adverse cardiovascular events (MACE) [2]. The pathophysiological mechanisms underlying these outcomes demonstrate the complex interplay between MetS components and myocardial dysfunction.

Conclusion: Metabolic Syndrome is a major health burden in critically ill patients with AMI, associated with a higher risk of specific in-hospital complications, even if its role in all- cause mortality is not definitively established. The underlying pathophysiology involves a complex interplay of systemic inflammation, endothelial dysfunction, and a prothrombotic state, which collectively drive myocardial fibrosis and ventricular hypertrophy, culminating in myocardial dysfunction. These findings underscore the critical need for early identification and aggressive management of MetS and its components to improve outcomes in this high-risk population. Further large-scale prospective studies are warranted to clarify the prognostic implications of MetS in the ICU.

The systematic review of multiple studies reveals several critical findings regarding the relationship between Metabolic Syndrome and myocardial dysfunction in the ICU setting.

Prevalence and Patient Characteristics

Metabolic Syndrome demonstrates a remarkably high prevalence among patients admitted to the ICU with acute myocardial infarction. In a comprehensive study conducted by Nguyen and colleagues in 2023, examining 199 patients who underwent primary percutaneous coronary intervention, the prevalence of MetS reached 68.3% [1]. This finding is consistent with earlier research from the Gulf Registry of Acute Coronary Events, which analyzed 8,716 consecutive patients across six Middle Eastern countries and found a prevalence of 46% [3]. The variation in prevalence rates across different populations underscores the global significance of this condition.

Patients with MetS present with distinct demographic and clinical characteristics. They are more likely to be female and demonstrate higher body mass indices, larger waist circumferences, and elevated rates of hypertension and diabetes mellitus compared to their non-MetS counterparts [1, 3]. These characteristics reflect the fundamental pathophysiological underpinnings of the syndrome, which are rooted in insulin resistance and adipose tissue dysfunction.

Clinical Outcomes and Complications

The impact of Metabolic Syndrome on in-hospital outcomes in critically ill patients with AMI is multifaceted. While the relationship between MetS and all-cause mortality remains somewhat controversial, with some studies reporting no significant association (OR, 4.92; 95% CI 0.62‒39.31, P = .13) [1], there is compelling evidence for increased cardiovascular mortality in patients with MetS (P = .03) [1]. This distinction suggests that MetS may influence the mode of death rather than overall mortality rates.

More consistently, MetS has been associated with a higher incidence of specific complications. Patients with MetS demonstrate significantly elevated rates of congestive heart failure and recurrent myocardial ischemia [1, 3]. In the context of ST- elevation myocardial infarction (STEMI), MetS is associated with increased risks of recurrent myocardial infarction and stroke [3]. Furthermore, increased waist circumference, a key component of MetS, has been identified as an independent predictor of all-cause mortality [1].

Component-Specific Effects

Analysis of individual MetS components reveals that certain elements carry particularly significant prognostic implications. Hyperglycemia emerges as a critical factor, associated with multi-vessel disease (OR=1.700, 95% CI=1.172-2.464, P=0.005) and higher Syntax scores (OR=2.736, 95% CI=1.241-6.032, P=0.013) [2]. In terms of long-term outcomes, both hyperglycemia (HR=2.904, 95% CI=1.847-4.567, P Less-than sign 0.001) and elevated BMI ≥28 kg/m² (HR=2.022, 95% CI=1.213-3.369, P=0.007) function as independent risk factors for major adverse cardiovascular events [2].

Pathophysiological Mechanisms

The pathophysiology of MetS-related myocardial dysfunction is complex and multifactorial. At the cellular level, insulin resistance and adipose tissue dysfunction promote a systemic proinflammatory state characterized by elevated levels of cytokines such as tumor necrosis factor-alpha, interleukin-6, and C-reactive protein. This inflammatory milieu contributes to endothelial dysfunction, reducing nitric oxide bioavailability and impairing vasodilation. Concurrently, MetS induces a prothrombotic state through increased levels of plasminogen activator inhibitor-1 and fibrinogen, elevating the risk of thrombotic complications.

These systemic derangements have direct consequences for the myocardium. Chronic inflammation and oxidative stress drive myocardial fibrosis and ventricular remodeling, while endothelial dysfunction impairs coronary microvascular perfusion. The combination of these factors results in progressive myocardial dysfunction, manifesting clinically as heart failure and increased susceptibility to ischemic events.

Clinical Implications

The findings of this systematic review carry important implications for the management of critically ill patients with AMI. The high prevalence of MetS in this population necessitates systematic screening and early identification. Given the prognostic significance of individual MetS components, particularly hyperglycemia and central obesity, targeted interventions addressing these factors may improve outcomes.

Management strategies should encompass both acute and long-term approaches. In the acute setting, aggressive glycemic control, blood pressure management, and lipid optimization are essential. Long-term management requires comprehensive lifestyle modifications, including dietary interventions, physical activity programs, and weight reduction strategies. Pharmacological interventions targeting insulin resistance, such as metformin, may offer additional benefits, although further research is needed to establish optimal therapeutic protocols in the ICU setting.