Clinically silent myocardial infarctions in the CKD community

Burden of clinically silent myocardial infarction in patients with kidney disease Patients with chronic kidney disease (CKD) and end-stage renal disease (ESRD) are at a greater risk for incident myocardial infarction and death from coronary heart disease (CHD) compared with the general population [1]. The presence of CKD may accelerate the formation of vulnerable plaques, increase the frequency of plaque disruption and may increase thrombogenicity of the blood, making patients with CKD at high risk for myocardial infarction and mortality. Once diagnosed with CHD, patients with CKD have a greater incidence of recurrent cardiovascular events and mortality [2]. Research has suggested that CHD is unique in patients with CKD and ESRD compared with the general population with early onset, more rapid progression, atypical symptoms and higher rates of death. Although it is estimated that ∼13% of patients with CKD have suffered an acute myocardial infarction [3], it is likely that many patients with CKD have clinically silent CHD, which may have serious clinical implications on long-term cardiovascular morbidity and mortality. In a provocative study in this issue of NDT, Rizk et al. examine the prevalence and long-term impact of unrecognized myocardial infarctions among patients with CKD. In this large study of 18 864 patients with and without CKD enrolled in the Reasons for Geographic and Racial Differences in Stroke (REGARDS) cohort, 12-lead ECGs were used to identify the presence of Q-wave abnormalities [4]. Recognized myocardial infarction was defined as the concurrence of self-reported myocardial infarction as well as Q-wave abnormalities on ECG, whereas unrecognized myocardial infarction was defined as the presence of diagnostic Q-wave abnormalities without self-report. The investigators report that, in patients with eGFR <30 mL/min/1.73 m 2 , the prevalence of unrecognized myocardial infarction was 13% compared with 4% in those without CKD [4]. The presence of macroalbuminuria was associated with a 10% risk of unrecognized myocardial infarction compared with 4% in patients without albuminuria. After 4 years of follow-up, the investigators found that among patients with CKD, the risk of death was similar in those with unrecognized versus recognized myocardial infarctions [4]. These compelling results suggest that unrecognized myocardial infarction appears to be more common in patients with CKD; and notably, unrecognized myocardial infarction conveys a similar negative prognosis compared with a clinically recognized myocardial infarction. This study makes an important contribution in being one of the first to define the burden of clinically silent myocardial infarctions in the CKD community. Several limitations of this study must be noted. The study cohort was primarily African-American (by design) so results may not be generalizable to other populations. This was a cohort that oversampled from the ‘stroke belt’ so participants likely had a higher prevalence of risk factors for stroke and thus CHD. The authors chose to utilize Q-wave abnormalities on baseline ECGs and self-report