European Malignant Hyperthermia Group 2025 guidelines for the investigation of malignant hyperthermia susceptibility.

Since malignant hyperthermia (MH) was first described in 1960, the number of cases of this potentially life-threatening reaction to anaesthesia with fatal or serious outcomes has been markedly reduced thanks to continuous advances in knowledge about triggering, clinical course, and treatment. Another essential and evolving pillar of patient safety remains diagnostics, which serve to confirm or rule out suspected cases of MH and to identify other individuals at risk of MH for prevention. For more than 40 yr, the British Journal of Anaesthesia has published the updated consensus diagnostic protocols of the European Malignant Hyperthermia Group at regular intervals. The presented diagnostic guidelines have been comprehensively revised 10 yr after the last update after substantial advances in DNA-based testing methods. In addition to the previous classification of MH susceptibility by the in vitro halothane/caffeine contracture test, a new diagnostic designation, the MH genotype, has been introduced. The latter is reflected in the revised diagnostic pathways, which also include the adapted European Malignant Hyperthermia Group curation system for the classification of genetic variants with regard to their relevance to MH. In addition to minor changes in the in vitro halothane/caffeine contracture test protocol, the guidelines address updated patient referral criteria and clinical interpretation of diagnostic results. And for the first time, the guidelines provide a consensus definition of a clinical MH event.