Precision medicine envisages the integration of an individual’s clinical and biological features obtained from laboratory tests, imaging, high-throughput omics and health records, to drive a personalised approach to diagnosis and treatment with a higher chance of success. As only up to half of patients respond to medication prescribed following the current one-size-fits-all treatment strategy, the need for a more personalised approach is evident. One of the routes to transforming healthcare through precision medicine is pharmacogenomics (PGx). Around 95% of the population is estimated to carry one or more actionable pharmacogenetic variants and over 75% of adults over 50 years old are on a prescription with a known PGx association. Whilst there are compelling examples of pharmacogenomic implementation in clinical practice, the case for cardiovascular PGx is still evolving. In this review, we shall summarise the current status of PGx in cardiovascular diseases and look at the key enablers and barriers to PGx implementation in clinical practice.

Introduction: Genetic factors affecting warfarin maintenance dose have been well established, but patient acceptance is a necessary consideration for the successful clinical implementation of warfarin pharmacogenetic testing (WPGT). In this study, we aimed to determine the attitudes toward WPGT among Singaporean Chinese.

Methods: A total of 194 warfarin patients and 187 members of the public completed a structured survey on paper and the Internet, respectively. Attitudes were expressed as willingness to undergo WPGT (single item with 5-point response) and expectations and concerns about WPGT (two multi-item scales). Relationships between attitudes and socio-demographic and clinical variables were explored using Fisher's exact test, Student's t-test, one-way analysis of variance or Pearson's correlation.

Results: Majority of respondents were willing to or neutral about undergoing WPGT. Both patients and public had relatively high expectations (mean [SD]: 3.77 [0.63], and 3.97 [0.55], respectively) and moderately high concerns (mean [SD]: 3.30 [0.69] and 3.33 [0.68], respectively) about WPGT. Willingness to undergo WPGT was associated with gender, educational status, length of warfarin treatment, and number of chronic diseases among warfarin patients, and with history of adverse drug reactions and number of chronic diseases among the public. Higher expectation of WPGT was associated with higher willingness (p < .001 in both populations), while higher concern was associated with lower willingness to undergo WPGT among the public (p = .004) but not among patients (p = .072).

Conclusion: Patient acceptance is not a major barrier to clinical implementation of WPGT but patient education is necessary and the ethical, social, and legal issues should be addressed.

Warfarin dosing for thromboprophylaxis in post-operative patients is time-consuming. Warfarin-dosing nomograms can be used in post-operative arthroplasty patients, but warfarin requirements are lower in frail older people. We modified an existing post-arthroplasty nomogram to a frail-friendly version and evaluated its performance in a frail elderly post-orthopaedic surgery on a geriatric rehabilitation ward to determine if it would improve quality indicators for oral anticoagulation. On a geriatric rehabilitation unit, post-operative orthopaedic patients were assigned to either physician-adjusted warfarin dosing or the nursing-administered nomogram. The proportion of days within target INR values was significantly higher in the nomogram group (77%, 95% CI 74% to 81%) compared to the physician-adjusted group (53%, 95% CI 46% to 60%), with no major bleeding or thromboembolic complications. The number of warfarin-related telephone calls to physicians was significantly reduced by tenfold. Use of a frail-friendly nomogram improved quality and efficiency of patient care on a geriatric rehabilitation unit.

A male infant, aged 2 month, with Kawasaki disease had a myocardial infarction despite intravenous infusions of gamma globulin and aspirin at high dosage. He developed progressively a thin walled, dilated aneurysm of the apex of the left ventricle which became lined with thrombus despite treatment with warfarin. Another boy, aged 6 years, was noted on the 10th day of the evolution of Kawasaki disease to have developed a giant aneurysm of the main stem of the left coronary artery. Despite infusion of gamma globulin, the aneurysm remained unaltered and developed a thrombus. The thrombus resolved following treatment with warfarin, though the giant aneurysm has persisted. These two cases illustrate the serious consequences that can follow Kawasaki disease despite management optimal by current standards.