Cholesterol end points predict outcome in patients with coronary disease: quality improvement metrics from the enhancing secondary prevention in coronary artery disease (ESP-CAD) trial.

Background: Achievement of target low-density lipoprotein (LDL) levels for secondary prevention is endorsed in Canadian guidelines but has been de-emphasized in the 2013 American College of Cardiology/American Heart Association coronary artery disease (CAD) guidelines in favor of initiation of statins or triple therapy (antiplatelet agent, angiotensin converting enzyme inhibitor/angiotensin II receptor blocker, and statins). Our objective was to determine which of these 3 process-of-care metrics achieved within 6 months would be associated with 5-year rates of death, myocardial infarction, or stroke and thus be suitable as an end point for quality improvement studies in patients with CAD.

Methods: This was a cohort study that followed 448 participants for 5 years after their involvement in a 6-month secondary prevention trial.

Results: Over 5 years, 37 patients died, 23 had myocardial infarction, and 20 had stroke. Six months after randomization, 125 (27.9%) had achieved the LDL target (≤ 2.0 mmol/L), 399 (89.1%) received statins, and 256 (57.1%) received triple therapy. The 5-year composite event rate was significantly lower in patients who achieved the LDL target during the 6-month trial than in those who did not (8.8% vs 17.3%; adjusted hazard ratio [aHR], 0.52; 95% confidence interval [CI], 0.27-0.99), even accounting for statin use (adjusted P = 0.038). Conversely, 5-year event rates were not lower in patients taking statins at 6 months compared with those who were not (14.8% vs 16.3%; aHR, 1.23; 95% CI, 0.58-2.61) or in those receiving triple therapy and those who were not (14.5% vs 15.6%; aHR, 1.17; 95% CI, 0.71-1.94).

Conclusions: Achievement of LDL targets at 6 months is suitable as a metric for CAD quality-improvement studies; medication use alone was not independently associated with longer term outcomes.