Objectives: To determine the prevalence of occult valvular pathology in afebrile injection drug users (IDUs) compared with an afebrile, non-IDU population. To characterize the type of valvular pathology present in light of current recommendations regarding periprocedural antibiotic prophylaxis against endocarditis.
Methods: This was a comparative, cross-sectional study involving a convenience sample of 98 patients with a history of injection drug use, and 99 non-IDU patients presenting to a large urban ED. Patients were excluded if they had one or more of the following: a history of cardiac valve abnormality, a history of endocarditis, fever on presentation, or a cardiac murmur. Data were collected that included demographics, medical history, and details of injection drug use. Transthoracic echocardiography (echo) was performed on each subject in the ED, and read in a blinded fashion by a single board-certified cardiologist.
Results: Among 98 IDUs and 99 non-IDUs, 12% of the IDUs had aortic valve thickening, compared with 5.1% of the non-IDUs (99% CI for difference of 7.8% = -3.0% to 18.6%). Forty-four percent of the IDUs had mitral valve thickening, compared with 25% of the non-IDUs (99% CI for difference of 18.3% = 0.9% to 35.7%). Eleven percent of the IDUs vs 1% of the non-IDUs had tricuspid valve thickening (99% CI for difference of 10.4% = 1.6% to 19.2%). No patient had pulmonic valve thickening. Six percent of the IDUs vs 0% of the non-IDUs had mitral annulus thickening (99% CI for difference of 6.3% = -0.1% to 12.8%). Twelve percent of the IDUs vs 3% of the non-IDUs had mitral chordae thickening (99% CI for difference of 9.5% = -0.4% to 19.4%). Tricuspid chordae thickening was recorded in 2% of the IDUs vs 0% of the non-IDUs (99% CI for difference of 2.1% = -1.7% to 6.0%). Most important, the prevalence of valvular regurgitation was small, and evenly distributed in the two groups. No valvular vegetations were seen.
Conclusion: Both non-IDUs and IDUs have occult valvular pathology. There is an increased prevalence in IDUs of tricuspid and mitral valve thickening. The prevalence of valvular regurgitation, a reported indication for periprocedural antibiotic prophylaxis, was small and the affected valves were not statistically different between the two groups. These findings question the selected routine use of antibiotic prophylaxis in IDU patients undergoing invasive procedures.