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Prognosis of Previous Silent MI in Patients Presenting With AMI
Study Questions:
What is the prevalence of silent myocardial infarction (MI) in patients presenting with first acute myocardial infarction (AMI), and its relation with mortality and major adverse cardiovascular events (MACE) at long-term follow-up?
Methods:
The investigators conducted a two-center observational longitudinal study in 392 patients presenting with first AMI between 2003 and 2013, who underwent late gadolinium enhancement cardiac magnetic resonance (LGE-CMR) examination within 14 days post-AMI. Silent MI was assessed on LGE-CMR images by identifying regions of hyperenhancement with an ischemic distribution pattern in other territories than the AMI. Mortality and MACE (all-cause death, reinfarction, coronary artery bypass grafting, and ischemic stroke) were assessed at 6.8 ± 2.9 years of follow-up. To investigate clinical outcome in patients with silent MI compared with patients without silent MI, Cox proportional hazards analyses were performed.
Results:
Thirty-two patients (8.2%) showed silent MI on LGE-CMR. Compared with patients without silent MI, mortality risk was higher in patients with silent MI (hazard ratio, 3.87; 95% confidence interval, 1.21-12.38; p = 0.023), as was risk of MACE (hazard ratio, 3.10; 95% confidence interval, 1.22-7.86; p = 0.017), both independent from clinical and infarction-related characteristics.
Conclusions:
The authors concluded that silent MI occurred in 8.2% of patients presenting with first AMI and was independently related to poorer long-term clinical outcome, with a more than threefold risk of mortality and MACE.
Perspective:
This observational study suggests that silent MI by LGE-CMR is a strong, independent predictor for adverse long-term clinical outcome, and the electrocardiogram has limited sensitivity for detection of silent MI and is not associated with long-term clinical outcome in this cohort. These data support the need for clinicians to recognize patients with prior silent MI as a high-risk subgroup. Additional studies are needed to further investigate pathophysiological mechanisms for the higher risk and to assess whether targeted therapies may ameliorate the risk associated with prior silent MI. We need to document potential clinical benefit to justify an expensive test in all patients presenting with AMI.
Keywords: Acute Coronary Syndrome, Brain Ischemia, Coronary Artery Bypass, Diagnostic Imaging, Electrocardiography, Gadolinium, Magnetic Resonance Imaging, Myocardial Infarction, Prevalence, Primary Prevention, Prognosis, Risk, Stroke
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