Liu, Taylor I.

OBJECTIVE To determine whether burden of multiple chronic conditions (MCCs) influences the risk of receiving inappropriate vs appropriate device therapies. DESIGN Retrospective cohort study. SETTING Seven US healthcare delivery systems. PARTICIPANTS Adults with left ventricular systolic dysfunction receiving an implantable cardioverter‐defibrillator (ICD) for primary prevention. MEASUREMENTS Data on 24 comorbid conditions were captured from electronic health records and categorized into quartiles of comorbidity burden (0‐3, 4‐5, 6‐7 and 8‐16). Incidence of ICD therapies (shock and antitachycardia pacing [ATP] therapies), including appropriateness, was collected for 3 years after implantation. Outcomes included time to first ICD therapy, total ICD therapy burden, and risk of inappropriate vs appropriate ICD therapy. RESULTS Among 2235 patients (mean age = 69 ± 11 years, 75% men), the median number of comorbidities was 6 (interquartile range = 4‐8), with 98% having at least two comorbidities. During a mean 2.2 years of follow‐up, 18.3% of patients experienced at least one appropriate therapy and 9.9% experienced at least one inappropriate therapy. Higher comorbidity burden was associated with an increased risk of first inappropriate therapy (adjusted hazard ratio [HR] = 1.94 [95% confidence interval {CI} = 1.14‐3.31] for 4‐5 comorbidities; HR = 2.25 [95% CI = 1.25‐4.05] for 6‐7 comorbidities; and HR = 2.91 [95% CI = 1.54‐5.50] for 8‐16 comorbidities). Participants with 8‐16 comorbidities had a higher total burden of ICD therapy (adjusted relative risk [RR] = 2.12 [95% CI = 1.43‐3.16]), a higher burden of inappropriate therapy (RR = 3.39 [95% CI = 1.67‐6.86]), and a higher risk of receiving inappropriate vs appropriate therapy (RR = 1.74 [95% CI = 1.07‐2.82]). Comorbidity burden was not significantly associated with receipt of appropriate ICD therapies. Patterns were similar when separately examining shock or ATP therapies. CONCLUSIONS In primary prevention ICD recipients, MCC burden was independently associated with an increased risk of inappropriate but not appropriate device therapies. Comorbidity burden should be considered when engaging patients in shared decision making about ICD implantation.

Background Patient sex and age may influence rates of death after receiving an implantable cardioverter‐defibrillator for primary prevention. Differences in outcomes other than mortality and whether these differences vary by heart failure symptoms, etiology, and left ventricular ejection fraction are not well characterized. Methods and Results We studied 2954 patients with left ventricular ejection fraction ≤0.35 undergoing first‐time implantable cardioverter‐defibrillator for primary prevention within the Cardiovascular Research Network; 769 patients (26%) were women, and 2827 (62%) were aged >65 years. In a median follow‐up of 2.4 years, outcome rates per 1000 patient‐years were 109 for death, 438 for hospitalization, and 111 for heart failure hospitalizations. Procedure‐related complications occurred in 8.36%. In multivariable models, women had significantly lower risks of death (hazard ratio 0.67, 95% CI 0.56 to 0.80) and heart failure hospitalization (hazard ratio 0.82, 95% CI 0.68 to 0.98) and higher risks for complications (hazard ratio 1.38, 95% CI 1.01 to 1.90) than men; patients aged >65 years had higher risks of death (hazard ratio 1.55, 95% CI 1.30 to 1.86) and heart failure hospitalization (hazard ratio 1.25, 95% CI 1.05 to 1.49) than younger patients. Age and sex differences were generally consistent in strata according to symptoms, etiology, and severity of left ventricular systolic dysfunction, except the higher risk of complications in women, which differed by New York Heart Association classification ( P =0.03 for sex–New York Heart Association interaction), and the risk of heart failure hospitalization in older patients, which differed by etiology of heart failure ( P =0.05 for age–etiology interaction). Conclusions The burden of adverse outcomes after receipt of an implantable cardioverter‐defibrillator for primary prevention is substantial and varies according to patient age and sex. These differences in outcome generally do not vary according to baseline heart failure characteristics.