Publication Title: CYP2C19 genetic testing for Mavacamten and ischaemic stroke treatment: What does the result mean for cardiovascular prescribers in the UK and Europe?
Authors: Emma F Magavern, John H McDermott, Mark J Caulfield, William G Newman, CYP2C19 genetic testing for Mavacamten and ischaemic stroke treatment: What does the result mean for cardiovascular prescribers in the UK and Europe?, European Heart Journal – Cardiovascular Pharmacotherapy, Volume 10, Issue 6, September 2024, Pages 481–483, https://doi.org/10.1093/ehjcvp/pvae040
Here’s what the new findings mean in practice for every cardiologist and stroke specialist across the UK and Europe:
- Executive Summary:
- For Mavacamten (a first-in-class myosin inhibitor in obstructive hypertrophic cardiomyopathy), regulators now mandate CYP2C19 genotyping because poor-metabolisers face a higher risk of systolic dysfunction from drug overexposure.
- For ischaemic stroke, up-to-30% of patients carry CYP2C19 loss-of-function alleles that reduce clopidogrel’s activation and raise recurrent-stroke risk; NICE therfore recommends routine genotyping to guide antiplatelet choice.
- Mavacamten: Incorporate CYP2C19 Genotyping Up-Front • What to do: Order a CYP2C19 test before you write that first mavacamten prescription. Poor metabolisers (two loss-of-function alleles) will have higher plasma levels—and a documented spike in type A adverse events—so dose reduction or even alternative therapies must be considered. • Implication: Genotype information should live in your EHR so each time you see “mavacamten,” clinical decision support flags high-risk genotypes.
- Ischaemic Stroke: Tailor Antiplatelet Therapy to patients Genotype • What to do: For patients post-TIA or ischaemic stroke, CYP2C19 testing at or soon after discharge identifies poor/intermediate metabolisers. If you uncover loss-of-function alleles, switch from clopidogrel to prasugrel or ticagrelor—agents whose efficacy isn’t CYP2C19-dependent3. • Implication: Embedding a genotype-guided stroke pathway (e.g., via your local genomic lab or point-of-care testing) can cut recurrent events and streamline prescribing.
- System-Level Calls to Action • Education & Governance: Most prescribers remain unaware of these mandates. Build multidisciplinary working groups (genetics, pharmacy, IT, cardiology, neurology) to draft local policies. • IT Integration: Liaise with your informatics team to ensure test results auto-link to prescribing modules with pop-up alerts for high-risk genotypes. • Reimbursement & Turnaround: Engage commissioners to cover genotyping costs and negotiate rapid turnaround (ideally ≤48 h) so acute decisions aren’t delayed.
- Bottom Line for Cardiovascular Prescribers • You now have two routine, actionable pharmacogenetic tests available: CYP2C19 for mavacamten and for antiplatelet therapy post-stroke. Ignoring them, risks avoidable adverse events and suboptimal treatment outcomes. • Its up to you to champion local implementation: shape pathways, train colleagues, and leverage decision support so that every prescription is both genetically and clinically precise.
References:
3)www.genomicseducation.hee.nhs.uk
