Modifiers of symptomatic embolic risk in infective endocarditis.
OBJECTIVE
To ascertain the impact of prior antiplatelet and statin therapy on symptomatic embolic events in [corrected] infective endocarditis (IE).


METHODS
We studied a retrospective cohort of adult patients with a diagnosis of IE who presented to Mayo Clinic (Rochester, MN) from January 1, 2003, to December 31, 2006. Patients were grouped into those who received treatment before infection or controls who did not receive treatment for both antiplatelet therapy and, separately, statin therapy. Because of the retrospective study design and thus the nonrandomized treatment groups, a propensity score approach was used to account for the confounding factors that may have influenced treatment allocation. Antiplatelet therapy included aspirin, dipyridamole, clopidogrel, ticlopidine or any combination of these agents. Statin therapy included atorvastatin, simvastatin, pravastatin, lovastatin, rosuvastatin, or fluvastatin. The primary end point was a symptomatic embolic event that occurred before or during hospitalization. Multivariable logistic regression was used to assess the propensity-adjusted effects of continuous daily therapy with antiplatelet and statin agents on risk of symptomatic emboli. Likewise, Cox proportional hazards regression was used to test for an independent association with 6-month mortality for each of the treatments.


RESULTS
The study cohort comprised 283 patients with [corrected] IE. Twenty-eight patients (24.1%) who received prior continuous antiplatelet therapy developed a symptomatic embolic event compared with 66 (39.5%) who did not receive such treatment. After adjusting for propensity to treat, the effect of antiplatelet therapy on embolic risk was not statistically significant (odds ratio, 0.71; 95% confidence interval [CI], 0.37-1.36; P=.30). Only 14 patients (18.2%) who received prior continuous statin therapy developed a symptomatic embolic event compared with 80 (39.4%) of the 203 patients who did not. After adjusting for propensity to treat with statin therapy, the benefit attributable to statins was significant (odds ratio, 0.30; 95% CI, 0.14-0.62; P=.001). The 6-month mortality rate of the entire cohort was 28% (95% CI, 23%-34%). No significant difference was found in the propensity-adjusted rate of 6-month mortality between patients who had and had not undergone prior antiplatelet therapy (P=.91) or those who had and had not undergone prior statin therapy (P=.87).


CONCLUSIONS
The rate of symptomatic emboli associated with IE was reduced in patients who received continuous daily statin therapy before onset of IE. Despite fewer embolic events observed in patients who received antiplatelet agents, a significant association was not found after adjusting for propensity factors. A continued evaluation of these drugs and their potential impact on subsequent embolism among IE patients is warranted.
Division of Cardiovascular Diseases, Mayo Clinic, 200 First St SW, Rochester, MN 55905, USA. anavekar.nandan@mayo.edu
Nandan S
NS
Anavekar
Jason C
JC
Schultz
Daniel D Correa
DD
De Sa
Justin M
JM
Thomas
Brian D
BD
Lahr
Imad M
IM
Tleyjeh
James M
JM
Steckelberg
Walter R
WR
Wilson
Larry M
LM
Baddour
D000293:Adolescent; D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D002648:Child; D002675:Child, Preschool; D004359:Drug Therapy, Combination; D004696:Endocarditis / Q000150:complications* / Q000188:drug therapy*; D005260:Female; D006801:Humans; D019161:Hydroxymethylglutaryl-CoA Reductase Inhibitors / Q000627:therapeutic use*; D007223:Infant; D016015:Logistic Models; D008297:Male; D008875:Middle Aged; D010975:Platelet Aggregation Inhibitors / Q000627:therapeutic use*; D057216:Propensity Score; D016016:Proportional Hazards Models; D012189:Retrospective Studies; D018570:Risk Assessment; D013923:Thromboembolism / Q000209:etiology* / Q000517:prevention & control*; D055815:Young Adult
D019161:Hydroxymethylglutaryl-CoA Reductase Inhibitors; D010975:Platelet Aggregation Inhibitors