BACKGROUND: Many patients experience a reduced quality of life for months after heart surgery. Besides medical factors, psychological factors such as preoperative expectations influence the recovery process. The ValvEx study investigated whether an expectation-focused preoperative intervention before heart valve surgery would (i) improve the postoperative recovery process by reducing illness-related disability and ii) impact secondary outcomes such as increased positive realistic expectations, and reduce preoperative anxiety. METHODS: N = 89 patients undergoing heart valve surgery were randomized into 1 of 2 groups after a baseline assessment: Standard medical care (SOC) vs SOC plus psychological expectation-focused intervention (EXPECT) on the day of hospital admission. Further assessments were conducted on the evening before surgery, 4 to 6 days and 3 months after surgery. The primary outcome was illness-related disability. Constrained longitudinal data analyses were conducted to analyze the intervention effects, while the need for information was considered as a potential moderator. RESULTS: No general effects were observed for the EXPECT intervention over time regarding the primary outcome illness-related disability (Pain Disability Index, PDI) and the secondary outcomes (P ≥ .167). The intervention effects were moderated by the individual need for information: Patients with a higher need for information who received the EXPECT intervention were less anxious on the evening before surgery (P = .020, d = 0.314) and less restricted in their quality of life 4 to 6 days after surgery compared to patients who received SOC (P = .005, d = 0.464). CONCLUSIONS: The ValvEx study is the first multicentre study investigating the expectation-optimizing preoperative intervention in heart valve patients. The implementation of the EXPECT intervention seemed to optimize outcomes after heart valve surgery for certain patients, such as patients with a high need for information. It is possible that there were no direct effects of the EXPECT intervention because the intervention dose was too low. These preliminary findings need to be corroborated by larger multicenter trials. Trial registration The study was preregistered at ClinicalTrials (identifier: NCT04502121, https://clinicaltrials.gov/study/NCT04502121).