Elevated low‐density lipoprotein cholesterol: An inverse marker of morbidity and mortality in patients with myocardial infarction

Abstract Background The incidence of atherosclerotic cardiovascular disease increases with levels of low‐density lipoprotein cholesterol (LDL‐C). Yet, a paradox may exist where lower LDL‐C levels at myocardial infarction (MI) are associated with poorer prognoses. Objective To assess the association between LDL‐C levels at MI with risk factor burden and cause‐specific outcomes. Methods Statin‐naive patients hospitalized for a first MI and registered in SWEDEHEART were included. Data were linked to Swedish registers. Primary outcomes were all‐cause mortality and nonfatal MI. Associations between LDL‐C and outcomes were assessed using adjusted proportional hazards models. Results Among 63,168 patients (median age, 66 years), the median LDL‐C level was 3.0 mmol/L (interquartile range 2.4–3.6). Patient age and comorbidities increased as LDL‐C decreased. During a median follow‐up of 4.5 years, 10,236 patients died, and 4973 had nonfatal MI. Patients with the highest LDL‐C had a lower risk of mortality (hazard ratio [HR] 0.75; 95% confidence interval [CI] 0.71–0.80). The risk of hospitalization for pneumonia, hip fracture, chronic obstructive pulmonary disease, and new cancer diagnosis was lower with higher LDL‐C (HR range, 0.40–0.81). Patients with the highest LDL‐C had a greater risk of recurrent MI (HR 1.16; 95% CI 1.07–1.26). Conclusions Patients with the highest LDL‐C levels at MI had the lowest incidence of mortality and morbidity. This seems to reflect lower age at MI, less underlying morbidities, paired with the modifiability of LDL‐C. However, supporting the causal association between LDL‐C and ischemic heart disease, elevated LDL‐C was simultaneously associated with an increased risk of nonfatal MI.