Lead-Dependent Infective Endocarditis: The Role of Factors Predisposing to Its Development in an Analysis of 414 Clinical Cases

Abstract

Background: Lead-dependent infective endocarditis (LDIE) is a serious and insidious infective disease spreading along the leads to valve leaflets and endocardial surface. LDIE is still a lesser known disease with unclear risk factors, most often evaluated jointly for all infectious complications.

Methods: Clinical data from 414 patients with the diagnosis of LDIE according to the Modified Duke Leads Criteria were analyzed. Patients with LDIE were identified in a population of 1,426 subjects submitted to transvenous lead extraction (TLE) in the Reference Center on Lead Extraction in Lublin, Poland, between March 2006 and July 2013 due to infectious (619 patients-43.4%) and noninfectious (807-56.6% of patients) reasons. During the period of 2006-2011, the analysis was conducted retrospectively; from early 2012 on, patients were enrolled prospectively. The effect of potential risk factors on the development of the disease was evaluated in a comparative analysis of clinical data from the LDIE patients and from 807 subjects with noninfectious indications for TLE. Additionally, in order to identify the factors predisposing to the development of LDIE, the population of infectious patients was divided into three subgroups: with isolated LDIE (157 patients), with LDIE and pocket infection (PI; 257 patients), and with isolated PI (205 patients). The groups and subgroups were analyzed for the presence of patient-dependent risk factors (age, gender, accompanying diseases, anticoagulation, or antiplatelet therapy) and procedure-related risk factors (the number and lead dwell time, pacing system, prior procedures, lead loops, and intracardiac abrasion of the leads). Furthermore, microbes' identification was conducted.

Results: The LDIE patients were older (67.3 vs 62.3; P = 0.001) and were more frequently male (68.6% vs 55.0%; P = 0.001) as compared with patients submitted to TLE for noninfectious reasons, but not in comparison with subjects diagnosed with isolated LDIE. In univariate analysis, the independent prognostic factors of LDIE were: type 2 diabetes-increase of risk by 37.7% (hazard ratio [HR] = 1,377; 95% confidence interval [CI] [1,088-1,742]), elevated above 2 mg% creatinine level-increase of risk by 61.5% (HR = 1,615; 95% CI [1,96-2,182]), antiplatelet therapy (HR = 1,285; 95% CI [1,052-1,057]), number of intracardiac leads prior to TLE (HR = 1,199; 95% CI [1,075-1,337]), intracardiac device with implantable cardioverter defibrillator (ICD) lead (HR = 1,909; 95% CI [1,492-2,444]), intracardiac device with coronary sinus lead (HR = 1,411; 95% CI [1,099-1,810]), number of procedures prior to TLE (HR = 1,092; 95% CI [1,017-1,172]), and abrasion of intracardiac leads (HR = 1,350; 95% CI [1,097-1,662]). Multivariate logistic regression demonstrated that the independent risk factors of LDIE were: chronic renal failure (HR = 1,406; 95% CI [1,033-1,915]), number of intracardiac leads prior to TLE (HR = 1,152; 95% CI [1,017-1,305]), intracardiac devices with ICD leads (HR = 1,719; 95% CI [1,330-2,223]), and presence of abrasion of intracardiac leads (HR = 1,405; 95% CI [1,129-1,750]). Microbiological analysis showed the domination of coagulase-negative staphylococci with relative advantage of Staphylococcus epidermidis in pathogenesis of LDIE.

Conclusions: The factors predisposing to LDIE are mainly related to procedures performed on the patients. LDIE develops more frequently in patients with multiple leads, especially ICD. An important, until now lesser known, risk factor for LDIE is intracardiac abrasion of the leads strongly connected with procedural agents and properties of specific kind of bacteries. A new concept of the pathogenesis of LDIE was proposed on the basis of present analysis.

Keywords: abrasion of the leads; lead-dependent infective endocarditis; risk factors.