‘Many heads are better than one’: a paradigm shift towards a multidisciplinary infective endocarditis management approach

Abstract

Infective endocarditis occurs at a frequency of 3–10 episodes per 100 000 person-years.^{1, 2} Despite being uncommon, the associated morbidity is substantial and the in-hospital mortality averages 15%–25% in published series.^{3, 4} The diagnosis and treatment have evolved in recent years, with advances in diagnostic clinical criteria, imaging techniques, microbiologic testing and antimicrobial treatment paradigms.^{5, 6} In spite of this, the global burden of endocarditis (incidence, mortality, disability-adjusted life-years (DALYs)) have increased since the 1990s.⁷ Attributable host and organism factors include progressively ageing and comorbid populations, expanding utilisation of immunosuppressive therapy, increasing deployment of invasive procedures and the emergence of Staphylococcus aureus as the predominant causative organism.⁷

The diagnosis of infective endocarditis remains challenging due to heterogeneous risk factors, microbiologic aetiology, clinical presentation and complications.^8-10 Significant expertise in affected organ systems is required for optimal management, for which a single clinician may not be able to fully provide.¹¹ Approximately 40%–50% of endocarditis cases require surgical intervention in the acute stage.⁸ While this may confer survival benefit, the perioperative risk may be substantial.^{10, 12} Therefore, the decision regarding surgical management should be discussed in the context of a multi-specialty meeting of clinicians involved in endocarditis treatment. Mestres and colleagues have succinctly described the role of endocarditis surgery with the comment ‘infective endocarditis is a medical-surgical disease in which surgical treatment is part of the therapeutic process rather than a result of the failure of medical treatment’.¹³

Systemic factors associated with the specialty-based and segregated approach to endocarditis management have also contributed to the rising trend in short- and long-term mortality.^{14, 15} These include delays in diagnosis and treatment, transfer to cardiothoracic surgical centres and treatment and inadequacy of long-term specialist follow-up.¹⁴ The reasons cited for diagnostic hold-up include admitting team inexperience, diagnostic imaging access issues, absence of positive blood cultures and suboptimal clinical information on transfer.¹⁵ Diagnostic delays, inaccurate referrals and tertiary centre capacity limitations may impede subsequent transfer.¹⁵ Failure to perform surgery for endocarditis may stem from diagnostic and transfer delays, prohibitive perioperative mortality and inefficient and time-consuming coordination between multiple specialties.¹⁵ Therefore, a multidisciplinary endocarditis team (MDET) approach would be the logical step in meeting the diagnostic and therapeutic obstacles encountered in endocarditis treatment.¹⁰

Interdisciplinary patient care has been successfully applied to cancer, coronary vascular and valvular heart disease and diabetic foot infection management.^16-19 Cross-specialty cooperation in endocarditis has been recommended as the standard of care by international society guidelines.^{9, 10, 18, 20} In addition to improving the accuracy of endocarditis evaluation, the MDET may promote judicious, timely and cost-effective use of diagnostic echocardiography and imaging modalities, through collaboration with cardiologists, radiologists and nuclear medicine physicians.²⁰

The utility of the MDET may extend to educational and research roles.¹¹ Continuing education of primary care practitioners and clinicians in non-tertiary centres by the MDET may improve diagnostic accuracy and speed outside of tertiary settings and therefore promote earlier transfer of care to cardiothoracic centres.¹¹ The development and maintenance of local endocarditis registries by the MDET may facilitate quality improvement through audits and mortality and morbidity reviews while also providing data for endocarditis-related research.¹¹ A comprehensive local database may support efforts to augment MDET funding and staffing.¹¹

The impact of the MDET has been evaluated in before-and-after observational studies.^{14, 21-25} These have been constrained by small sample sizes, short follow-up periods and inherent biases resulting from non-randomised designs. All study samples have been derived from tertiary institutions only and are, therefore, not fully representative of the actual populations.

Notwithstanding these limitations, significant reductions in short- and long-term mortality have been shown in most of these trials.^{14, 21, 23-25} Additionally, the absence of MDET management has correlated with increased mortality in multivariate analyses.^21-23 Shortening of time to cardiac surgery has been revealed in studies by Kaura et al. and Ruch et al.^{21, 22} Diab et al. and Sadeghpour et al. have reported improved endocarditis complication rates.^{23, 24} Other tangible benefits include a decrease in the time to commencement of antimicrobial therapy and length of hospitalisation.^{21, 22} A systematic review and meta-analysis of 15 observational studies of the impact of MDETs (which included all of the above trials) has demonstrated improved mortality (risk ratio of 0.61 (95% confidence interval 0.47–0.48; I² 62%)), shortened time to surgery and increased rate of surgery.²⁶

Notwithstanding the abundance of research evidence in support of interdisciplinary collaboration in endocarditis management and its consistent promotion by international guidelines, the models of endocarditis care in Australia are unclear. Specifically, the extent, impediments and enablers of national MDET implementation and clinician perspectives remain to be elucidated.

Robson and colleagues have conducted a groundbreaking and timely observational study to characterise the existing endocarditis management systems in Australia and to explore the challenges associated with local MDET establishment.²⁷ The two-part, anonymous electronic survey questionnaires were distributed to infectious diseases physicians, clinical microbiologists and cardiologists and cardiac surgeons at Australian cardiac surgical centres through professional society membership lists and investigators' specialty networks.

Less than a third (28%) of surveyed sites have implemented MDETs, with over two-thirds of these having been established within the preceding 5 years. A majority were spearheaded by cardiology departments (46%), met weekly (53%) and were selective in case discussion (85%). Cardiac surgery input is more likely to be sought for complex cases compared with less complicated infections (91% vs 57%). Similarly, the MDET meetings were utilised more frequently for complicated cases as opposed to less intricate infections (34% vs 21%). Most responders were supportive of the MDET care method, in terms of general utility, diagnostic benefit, reduction of case mismanagement, decreasing time to surgery, compliance improvement and enhancement of interdisciplinary communication. However, attitudes from cardiac surgical centre participants are generally more positive across all parameters. Replies to questions on mortality benefit and patient satisfaction from all clinicians surveyed were generally more moderated. Approximately three-quarters of responding clinicians have favourable opinions of their MDETs (76%). A range of structural and functional hurdles have been cited, with the lack of capacity and motivation for the integration of collaborative endocarditis-related activity into existing complex health services being highlighted as key barriers. However, the lack of specific specialties has not been shown to be responsible for the institutional absence of MDETs.

The authors are to be commended for carrying out an inclusive survey. A majority of Australian cardiac surgical hospitals have participated in the audit (84%), including private and public institutions as well as high- and low-volume centres. Part 2 of the survey has been distributed to over 1800 recipients, with subsequent responses from clinicians representing seven different specialties. Nevertheless, only 38% of responders are non-infectious diseases or clinical microbiology clinicians. Participation from other MDET specialists should be encouraged for future Australian endocarditis studies, given that infection management experts, cardiologists and cardiac surgeons have been recommended as ‘core’ MDET members.^{13, 15, 20} The viewpoints of non-cardiac centre physicians on interdisciplinary endocarditis collaboration should also be explored, to diverge from tertiary-centric endocarditis research.

Comprehensive recommendations have been systematically proposed in the paper by Robson and colleagues.²⁷ Key priorities should include the development of national endocarditis MDET guidelines and the establishment of a nationwide registry. Guidelines should be derived from extensive consultation and appraisal of the prevailing evidence and similar in concept to those for diabetic foot infection management in Australia.¹⁹ Pragmatic and step-by-step MDET implementation guidance has been discussed in international guidelines and should be adapted and integrated into the Australian context.^{13, 20} Robust guidelines may facilitate the formation of an inclusive and functional national endocarditis registry, through the adoption of the MDET model by a wide range of cardiac surgical and other institutions.

An Australian registry may promote institutional quality improvement in various aspects of endocarditis diagnosis and management through national benchmarking. Research that utilises patient samples pooled from a comprehensive national registry may reach substantial statistical power to successfully address important knowledge gaps. Registry-based audit and research data may encourage greater adoption of the MDET and improve the functioning of existing teams. An inclusive registry may enhance collaboration between tertiary and other centres within the MDET framework, therefore optimising care of patients in their treatment journey between these institutions. National and institutional outcome data may be used in support of MDET service enhancements.

Infective endocarditis continues to present significant diagnostic and therapeutic challenges. These are not being adequately addressed by the traditional and disparate model of endocarditis care, which, when coupled with changing epidemiology, have resulted in rising global disease burden. A multidisciplinary team-based management paradigm has been associated with improved outcomes, endorsed by international experts and appears to be widely accepted. Despite this, interdisciplinary collaboration in endocarditis care remains limited, as a result of structural and functional barriers. The successful establishment of MDETs across Australia will depend on implementation of various recommendations, particularly in relation to national MDET guidelines and a nationwide registry.