Impact of Iron Deficiency on Response to and Remodeling After Cardiac Resynchronization Therapy

Iron deficiency is prevalent in heart failure with reduced ejection fraction and relates to symptomatic status, readmission, and all-cause mortality. The relation between iron status and response to cardiac resynchronization therapy (CRT) remains insufficiently elucidated. This study assesses the impact of iron deficiency on clinical response and reverse cardiac remodeling and outcome after CRT. Baseline characteristics, change in New York Heart Association functional class, reverse cardiac remodeling on echocardiography, and clinical outcome (i.e., all-cause mortality and heart failure readmissions) were retrospectively evaluated in consecutive CRT patients who had full iron status and complete blood count available at implantation, implanted at a single tertiary care center with identical dedicated multidisciplinary CRT follow-up from October 2008 to August 2015. A total of 541 patients were included with mean follow-up of 38 ± 22 months. Prevalence of iron deficiency was 56% at implantation. Patients with iron deficiency exhibited less symptomatic improvement 6 months after implantation (p value <0.001). In addition, both the decrease in left ventricular end-diastolic diameter (-3.1 vs -6.2 mm; p value = 0.011) and improvement in ejection fraction (+11% vs +15%, p value = 0.001) were significantly lower in patients with iron deficiency. Iron deficiency was significantly associated with an increased risk for heart failure admission or all-cause mortality (adjusted hazard ratio 1.718, 95% confidence interval 1.178 to 2.506), irrespectively of the presence of anemia (Hemoglobin <12 g/dl in women and <13 g/dl in men). In conclusion, iron deficiency is prevalent and affects both clinical response and reverse cardiac remodeling after CRT implantation. Moreover, it is a powerful predictor of adverse clinical outcomes in CRT.