Clinical characterization and natural history of chemotherapy‐induced dilated cardiomyopathy

AIMS: Chemotherapy‐induced dilated cardiomyopathy (CI‐DCM) is a well‐recognized phenotype of non‐ischemic dilated cardiomyopathy (DCM), characterized by poor outcomes. However, a detailed comparison between idiopathic DCM (iDCM) and CI‐DCM is still lacking. METHODS AND RESULTS: All consecutive DCM patients enrolled in the Trieste Muscle Heart Disease Registry were analysed. CI‐DCM and iDCM were defined according to current recommendations. The primary study outcome measure was all‐mortality death and secondary outcomes were a) a composite of cardiovascular death/heart‐transplantation/ventricular‐assist‐device implantation, and b) major ventricular arrhythmias. The study included 551 patients (499 iDCM and 52 CI‐DCM). At enrolment, compared with iDCM, CI‐DCM patients were older (51 ± 14 years vs. 58 ± 3 years, respectively, P < 0.001) and had a higher left ventricular ejection fraction (32% ± 9 vs. 35% ± 10, respectively, P = 0.03). Over a median follow‐up of 90 months (IQR 54–140 months), CI‐DCM patients had a higher incidence of all‐cause mortality compared with iDCM (36.5% vs. 8.4% in CI‐DCM and iDCM respectively, P < 0.001), while the incidence of major ventricular arrhythmias was higher in the iDCM group compared with CI‐DCM (4% vs. 0%, in CI‐DCM and iDCM respectively, P = 0.03). The risk of the composite outcome was comparable between the two groups (P = 0.91). At Cox multivariable analysis, the diagnosis of CI‐DCM emerged as independently associated to primary outcome (HR 6.42, 95% C.I. 2.52–16.31, P < 0.001). CONCLUSIONS: In a well‐selected DCM cohort, patients with a chemotherapy‐induced aetiology had a higher incidence of all‐cause mortality compared with iDCM. Conversely, the incidence of life‐threatening ventricular arrhythmic events was higher among patients with iDCM.