AbstractAimCurrent literature lacks a definitive threshold of idiopathic premature ventricular complex (PVC) burden for predicting cardiomyopathy (CMP). The main objective of the present study was to evaluate relationship between the PVC burden and left ventricular ejection fraction (LVEF).MethodThis multicenter, cross‐sectional study included 341 consecutive patients with more than 1,000 idiopathic PVC in 24 hr of Holter monitoring admitted to the cardiology clinics between January 2019 and May 2019 in the nineteen different centers. The primary outcome was the LVEF measured during the echocardiographic examination.ResultOverall, the median age was 50 (38–60) and 139 (49.4%) were female. Percentage of median PVC burden was 9% (IQR: 4%–17.4%). Median LVEF was found 60% (55–65). We used proportional odds logistic regression method to examine the relationship between continuous LVEF and candidate predictors. Increase in PVC burden (%) (regression coefficient (RE) −0.644 and 95% CI −1.063, –0.225, p < .001), PVC QRS duration (RE‐0.191 and 95% CI −0.529, 0.148, p = .049), and age (RE‐0.249 and 95% CI −0.442, −0.056, p = .018) were associated with decrease in LVEF. This inverse relationship between the PVC burden and LVEF become more prominent when PVC burden was above 5%. A nomogram developed to estimate the individual risk for decrease in LVEF.ConclusionOur study showed that increase in PVC burden %, age, and PVC QRS duration were independently associated with decrease in LVEF in patients with idiopathic PVC. Also, inverse relationship between PVC burden and LVEF was observed in lower PVC burden than previously known.