Feasibility and Findings of Including Self-Identified Adult Congenital Heart Disease Patients in the INVESTED Trial

Background Adult congenital heart disease (ACHD) patients have significant morbidity and rise in cardiac admissions. Their outcome with high-dose influenza vaccination is unknown in comparison to those without ACHD. Objectives The purpose of this study was to compare all-cause mortality or cardiopulmonary hospitalizations in self-identified ACHD versus non-ACHD patients receiving high- or low-dose influenza vaccination within the INfluenza Vaccine to Effectively Stop cardioThoracic Events and Decompensated heart failure trial. Methods We prospectively included ACHD patients in the INVESTED (INfluenza Vaccine to Effectively Stop cardioThoracic Events and Decompensated heart failure) trial. The primary end point was all-cause death or hospitalization for cardiovascular or pulmonary causes. Results Of the 272 ACHD patients, 132 were randomly assigned to receive high-dose trivalent and 140 to standard-dose quadrivalent influenza vaccine. Compared to the non-ACHD cohort (n = 4,988), ACHD patients were more likely to be younger, women, smokers, have atrial fibrillation, and have a qualifying event of heart failure. The primary outcome was 49.8 events versus 42.8 events per 100 person-years (adjusted HR: 1.17; 95% CI: 0.95-1.45; P = 0.144) in the ACHD group and non-ACHD group, respectively. The interaction between ACHD status and randomized treatment effect was not significant for the primary outcome (P = 0.858). Vaccine-related adverse events were similar in both groups. Conclusions Patients who self-identify as being ACHD had similar primary outcome of all-cause death or hospitalization for cardiovascular or pulmonary causes compared to non-ACHD cohort. High-dose influenza vaccination was similar to standard-dose influenza vaccination on the primary outcome in patients who self-identify as ACHD.