In this interesting special collection of articles from Cardiac Failure Review on imaging in heart failure (HF), the authors splendidly highlight the key features and essential roles of an appropriate imaging evaluation in the assessment and management of the wide spectrum of HF phenotypes.
Heart Failure with Reduced Ejection Fraction
Starting with HF with reduced ejection fraction (HFrEF), Drs Gosling and Al-Mohammad provide a thorough insight on the multiple, fundamental roles played by different cardiac imaging modalities.1 The accurate quantification of ventricular volumes and function is indeed essential for HFrEF diagnosis, with transthoracic echocardiography (TTE) and cardiac magnetic resonance imaging (CMR) remaining the most commonly used modalities. Furthermore, precise assessment of valvular heart disease, myocardial tissue characterisation with scar identification and ischaemic testing are shown not only to play a relevant part in understanding HF aetiology, but also to have important implications on treatment planning and prognostication. In particular, the authors illustrate how imaging may guide decisions on coronary revascularisation and valvular heart disease intervention, diuretic therapy titration and device implantation, such as CRT and left ventricular assist device.
As for prognostication, cardiac imaging can help evaluate the presence of established predictors of worse prognosis, such as ventricular adverse remodelling, extensive scars and pulmonary hypertension. However, in future it is expected to gain increasing relevance in the identification of new possible prognosticators, as the emerging cardiac meta-iodobenzylguanidine (mIBG)-derived increased sympathetic activity and myocyte apoptosis using 99 mTc annexin 5.
Heart Failure with Preserved Ejection Fraction
Turning to HF with preserved ejection fraction (HFpEF), a relevant global health problem with significantly increasing incidence, its diagnosis mainly depends on demonstrating diastolic left ventricle (LV) dysfunction and excluding other cardiac and non-cardiac pathologies. Dr Ünlü et al. offer a comprehensive guide on multimodality imaging parameters for the assessment of the presence and the degree of diastolic LV dysfunction.2 While echocardiography represents the first-line modality, cardiac computed tomography and nuclear methods are presented as helpful tools for the definitive diagnosis of the underlying aetiology of HFpEF. As for CMR, in particular late gadolinium enhancement and extracellular volume calculation, it has certainly become a cornerstone in this work-up. Considering that patients with HFpEF develop symptoms on exertion, exercise testing has been regarded as crucial in cases of suspected diastolic dysfunction. Yet, the authors emphasise the importance of other clinical features that should always be considered, as imaging estimates of LV filling pressure have only moderate accuracy.
Interestingly, HFpEF has a higher prevalence in female patients, and this trend becomes more evident with increasing age. Nevertheless, women are often underrepresented in clinical trials; therefore, current evidence and recommendations do not necessarily reflect best practice for these patients.
The enlightening paper by Dr Leo et al. focuses on sex-related differences as well as analogies in HFpEF and HFrEF presentation, highlighting the role of each imaging modality in the diagnosis and follow-up.3 In particular, the authors underline women’s unique anatomical and physiological features, such as smaller volumetric measures, higher median LV ejection fraction (LVEF), suggesting the need for sex-specific thresholds to define normal LVEF, and lower degree of LV hypertrophy compared to their male counterparts.
Furthermore, important insights are dedicated to cardiovascular imaging assessment during pregnancy and peripartum, in women presenting with chemotherapy-induced cardiomyopathy (i.e. breast cancer-related), takotsubo syndrome and microvascular dysfunction, with the latter two conditions especially affecting female patients. The authors conclude that undoubtedly more scientific data are needed to support the management of women in HF in clinical practice.
Valvular Heart Disease
Focusing on the role cardiac imaging plays in valvular structural interventions, Dr Grigoryan et al. present detailed instructions on how to perform an individualised, multimodality imaging assessment for all the available interventional procedures, from transcatheter aortic valve replacement to mitral and tricuspid different valve repair or replacement techniques.4 Every modality has its strengths and weaknesses in each setting. However, as the authors correctly point out, while the new indications for percutaneous therapies continue to expand and evolve, the establishment of heart valve centres with multimodality imaging assessment and a heart team approach (including an imaging cardiologist) should be considered of utmost importance.
What Does the Future Hold for Imaging in Heart Failure?
The future of imaging as a guide for early detection of heart failure is bright. Recently, the PARAGON-HF investigators focused on the value of right ventricular (RV) free wall strain and the coupling in HFprEF patients, demonstrating worsening RV function and its ratio to pulmonary pressure, is common and significantly associated with an increased risk of HF hospitalisations and CV death.5
New imaging algorithms will help assessing regional strain and its response following guideline-directed medical management. Imaging, together with new techniques such as interatrial shunt, will contribute towards effective management of HF. Furthermore, percutaneous structural interventions have exploded offering a solution in HF patients with significant valvular heart disease.
Advanced imaging of venous, pulmonary and renal congestion by ultrasound gives us a better understanding of the mechanism of heart failure, while fusion imaging and advanced techniques such as 4D flow have a great future in the understanding of complex pathology for example in congenital heart disease or structural interventions.6,7 Furthermore, 3D printing remains an incredible tool for the better understanding of complex anatomy.
Conclusion
These valuable review articles provide detailed guidance on multimodality assessment in both HFrEF and HFpEF patients, with special focuses on two conditions which have been attracting increasing attention over the last few years, the characterisation of women’s unique cardiac features and individualised assessment for percutaneous valve intervention.