The European Registry for Patients with Mechanical Circulatory Support (EUROMACS) of the European Association for Cardio-Thoracic Surgery Fourth report: Focus on standardized outcome ratios.

Objectives: This fourth report aimed to provide insights into patient characteristics, outcomes, and standardized outcome ratios of patients implanted with durable Mechanical Circulatory Support across participating centers in the European Registry for Patients with Mechanical Circulatory Support (EUROMACS) registry.

Methods: All registered patients receiving durable mechanical circulatory support up to August 2024 were included. Expected number of events were predicted using penalized logistic regression. Standardized outcome ratios (Observed/Expected events) were presented in plots to assess 30-day and 1-year mortality, ischaemic stroke, and major bleeding outcomes. Expected events were estimated using penalized logistic regression using demographics and comorbidities as predictors. Centers with <90% follow-up completeness were excluded from standardized outcome ratio assessment.

Results: Analysis included 6962 implants in 6408 patients (457 patients underwent repeated implants) registered in EUROMACS from 17 countries (32 centres) (median age: 58 years, 83% males, 17% INTERMACS class 1). Thirty-day mortality, major bleeding and ischaemic stroke probabilities were 9.6, 12.6%, and 2.1%, respectively. Standardized mortality ratios showed variability between centres, ranging from 0 (95% CI : 0-0) to 1.4 (95% CI : 1.2-1.7). Higher standardized bleeding outcome ratios correlated with higher standardized ischaemic stroke ratio's (Spearman r: 0.56, P = 0.008).

Conclusions: Most included centers perform as expected given the demographics and comorbidities of patients. A positive correlation was found between standardized bleeding and ischaemic stroke ratios, reflecting the need of continuously monitoring of adverse events by quality improvement programs.