Abstract Background Patients, whose non-emergency cardiac procedure was postponed during the COVID-19 pandemic, have shown signs of disease progression in the short term. Data on the long-term effects are currently lacking. Aim To assess outcomes through 3 years following deferral. Methods This retrospective, single-center analysis includes consecutive patients whose non-emergency cardiovascular intervention was postponed during the first COVID-19-related lockdown (March 19 to April 30, 2020). Outcomes over 36 months post-procedure were analyzed and compared to a seasonal control group undergoing non-emergency intervention in 2019 as scheduled (n = 214). The primary endpoint was a composite of emergency cardiovascular hospitalization and death. Additionally, NT-proBNP levels were analyzed. Results The combined endpoint occurred in 60 of 178 patients (33.7%) whose non-emergency transcatheter heart valve intervention, rhythmological procedure, or left heart catheterization was postponed. Primary endpoint events did not occur more frequently in the study group during the 36-month follow-up (p = 0.402), but within the first 24 months post-procedure (HR 1.77, 95% CI 1.20–2.60, p = 0.003). Deferred patients affected by an event in the postprocedural 24 months had significantly higher NT-proBNP levels at the time of intervention (p < 0.001) (AUC 0.768, p = 0.003, optimum cut-off 808.5 pg/ml, sensitivity 84.2%, specificity 65.8%) and thereafter (p < 0.001). Conclusion Deferral of non-emergency cardiovascular interventions is associated with poor outcomes up to 24 months post-procedure. Adverse effects affect patients who develop signs of acute heart failure, as indicated by NT-proBNP, prior to treatment. These findings could help improve resource allocation in times of limited capacity. Graphical Abstract