Imaging in patients with advanced therapies for heart failure.

Although the number of heart transplants performed in North America has been relatively stable over the last decade, median survival has steadily improved, according to the ISHLT Transplant Registry. Likewise, the number of continuous flow left ventricular assist devices (LVADs) implanted each year in the United States has more than quintupled in 5 years, reaching a total of 2,420 implanted in 2013, according to the Sixth INTERMACS annual report. The number of heart failure patients therefore is growing considerably, and so is the prevalence of the advanced therapies which require close and continuous monitoring and management. In this issue of the Journal, Gupta et al have provided a broad and comprehensive yet succinct survey of the most recent literature describing multiple imaging modalities as they relate to the transplant and LVAD populations. Although imaging choice tends to lean heavily on what techniques are available or on institutional expertise, it is important to stay informed of the status and developments in other imaging modalities as research and patient care progresses at an unparalleled rate. Transplant recipients face certain challenges related to the therapeutic window wherein the degree of immunosuppression to suppress rejection must be balanced with the short-term risk for infection and long-term risk for malignancy, each of which are represented in the leading causes of death in this population. Monitoring the function of the transplanted heart is most easily done with standard echocardiography techniques. Gupta et al also touch on cardiac magnetic resonance (CMR), which can provide additional information that echo cannot accurately determine, such as presence of myocardial scar and right ventricular end diastolic volume index, which appear to be independent predictors of cardiovascular outcomes. Cardiac allograft vasculopathy is another significant cause of morbidity and mortality in post-transplant patients that has led to needed, and often impressive, investigation into the accurate and early detection of this potentially reversible condition. The current gold standard, invasive coronary angiography, has limitations related to the nature of the disease. Allograft vasculopathy and coronary atherosclerosis are distinct entities, the former thought to be driven by, among other things, non-self major histocompatibility complexes, e.g. HLADR, and the failure of outward remodeling as compensation for neointimal hyperplasia due to expansion of vascular smooth muscle cells. Allograft vasculopathy is diffuse, involving large epicardial and smaller intramyocardial arteries, and its course is unpredictable, and often clinically silent due to denervation. Approximately 10% of patients die in the 12 months following a diagnosis of cardiac allograft vasculopathy. Yet, there are available therapies such as pharmacologic inhibition/modulation of cellular proliferative signaling, which have been associated with reduced incidence and slower progression; thus the need for early and accurate detection is paramount. Invasive catheter-based conventional coronary angiography has long been the See related article, pp. 617–638