Importance

The extent to which levels of high-sensitivity C-reactive protein (hs-CRP), a known marker of increased cardiovascular risk, are elevated and are associated with standard cardiovascular risk factors in patients with a history of myocardial infarction (MI) is unknown.

Objectives

To determine the pattern and determinants of the distribution of hs-CRP in those with a prior MI in the United States using a nationally representative sample.

Design and participants

Adults with hs-CRP data in the National Health and Nutrition Examination Surveys from 1999-2010.

Results

Among 1296 individuals in our cohort, the median age was 65 years and the median hs-CRP level was 2.69 mg/L, measured an average of 7.1 years after the MI. Among these patients, 22% had hs-CRP levels of <1 mg/L, 61% had ≥2 mg/L, and 48% had ≥3 mg/L. Increasing hs-CRP was associated in a multivariable model with increasing body mass index (partial R² [pR²] 0.113, P < .001), increasing non-high-density lipoprotein [HDL] (pR² 0.030, P < .001), increasing age (pR² 0.008, P = .017), and decreasing HDL (pR² 0.005, P = .046). Adjusted mean hs-CRP was also higher in women (3.6 vs 2.7 mg/L; P < .001), in people with hypertension (3.5 vs. 2.8, P = .030), and among smokers (4.2 vs 2.3 mg/L; P < .001), and lower in people with hyperlipidemia (2.8 vs. 3.5, P = .007). Standard cardiovascular risk factors accounted for only 22% of the variability in hs-CRP levels.

Conclusions and relevance

Among patients with prior MI, elevated hs-CRP is prevalent several years after the MI, and standard cardiovascular risk factors explain only a small proportion of hs-CRP variability. In light of emerging evidence on the importance of inflammation in the pathogenesis of cardiovascular disease, the high prevalence of elevated hs-CRP in patients with prior MI in the United States may have public health implications.

Background

There is limited information about the long-term survival of older patients after myocardial infarction (MI).

Methods and results

CRUSADE (Can rapid risk stratification of unstable angina patients suppress adverse outcomes with early implementation of the ACC/AHA guidelines) was a registry of MI patients treated at 568 US hospitals from 2001 to 2006. We linked MI patients aged ≥65 years in CRUSADE to their Medicare data to ascertain long-term mortality (defined as 8 years post index event). Long-term unadjusted Kaplan-Meier mortality curves were examined among patients stratified by revascularization status. A landmark analysis conditioned on surviving the first year post-MI was conducted. We used multivariable Cox regression to compare mortality risks between ST-segment-elevation myocardial infarction and non-ST-segment-elevation myocardial infarction patients. Among 22 295 MI patients ≥ age 65 years (median age 77 years), we observed high rates of evidence-based medication use at discharge: aspirin 95%, β-blockers 94%, and statins 81%. Despite this, mortality rates were high: 24% at 1 year, 51% at 5 years, and 65% at 8 years. Eight-year mortality remained high among patients who underwent percutaneous coronary intervention (49%), coronary artery bypass graft (46%), and among patients who survived the first year post-MI (59%). Median survival was 4.8 years (25th, 75th percentiles 1.1, 8.5); among patients aged 65-74 years it was 8.2 years (3.3, 8.9) while for patients aged ≥75 years it was 3.1 years (0.6, 7.6). Eight-year mortality was lower among ST-segment-elevation myocardial infarction than non-ST-segment-elevation myocardial infarction patients (53% versus 67%); this difference was not significant after adjustment (hazard ratio 0.94, 95% confidence interval, 0.88-1.00).

Conclusions

Long-term mortality remains high among patients with MI in routine clinical practice, even among revascularized patients and those who survived the first year.