Stress echocardiography: no more challenges!

Stress echocardiography is an established technique in clinical cardiology for the assessment of patients with known or suspected coronary artery disease.1 It has been shown to be a suitable tool for prognostic purposes in several clinical conditions such as diabetes,2,3 hypertension,4,5 heart failure.6,7 However, there is a wide gap between scientific evidence and guidelines and the clinical use on a routine basis in echocardiographic laboratories. The routine use remains restricted to few laboratories with large volumes and specific expertise, in the face of its low cost (much lower than any other technique for ischemia detection) and the wealth of information it may provide in one sitting. Many reasons have been suggested from a highly specialized personnel to the lack of an objective independent gold standard, the need for a dedicated training and its maintenance over time, the overall volume of each individual laboratory, on top of the familiarity with the different type of stressors in order to individualize the clinical question. Most of the aforementioned reasons apply to medical imaging and they cannot be considered obstacles to the diffusion of a technique that in the last 25 years moved from a promising tool to an established one.8 Senior and his group have spent a lot of energy in showing the clinical cardiology community that stress echocardiography should be used on a much wider scale, anytime it is indicated. They are one of the main advocates for the routine clinical use of this technique and their body of work is dedicated not only to support scientific evidence but also to show that it is a feasible and suitable technique in most conditions and in many difficult ones such as left bundle branch block (LBBB) patients. In this retrospective analysis of a single experience institution on 190 patients, an abnormal stress echo (myocardial ischemia and/or abnormal LV function) predicted an almost three-fold increase in all-cause mortality and cardiovascular events compared with normal stress echo.9 If this result does not come unexpected,10–12 there are a few features of this study that need to be highlighted: one is related to stress echo reading and interpretation, the other to the parameters that make a test positive. Due to the intrinsic difficulty of image interpretation in patients with LBBB, authors do not use simple wall motion score index but wall thickening. The paradoxical movement of the septum and the rocking of the heart in LBBB makes stress echo interpretation more difficult and with the potential of inflating false positive test results. Wall thickening is the perfect parameter to overcome this danger and it is the one that should be observed during stress echo challenge. They also included an abnormal LV as a marker of outcome. Several studies have shown the clinical usefulness of including a parameter of global function during stress echo, especially in negative test for wall motion score index.13 Echo contrast infusion favours interpretation in difficult cases and enhances the analysis of wall thickening. The main message is that independent of the underlying mechanism (ischemic or non-ischemic) stress echo positivity is an excellent risk stratifier and is able to identify patients at different level of risk of experiencing events during the follow-up. Moreover, it identifies those at very high risk needing a prompt treatment of CAD disease with revascularization. So far, so good. What most of these retrospective studies are unable to tell, is the real impact of revascularization (does it change outcome when ischemia guided?), of medical therapy modifications and risk reduction by life-style changes intensification. It is time to fill the gap and provide strong evidence to the clinical community that stress echo has the potential to provide these answers through well designed, prospective and randomized trials. These authors have shown how rich is the information obtained during the conventional time of physical or pharmacologic stress echo, without any particular change of the routine procedure. Tailoring the test on the basis of clinical question, patient characteristics using the most appropriate technology is the target of the new generation of studies on stress echocardiography, also beyond coronary artery disease. These authors are in line with the invitation coming from other experts in the field stating that ‘stress echocardiography is useful and convenient in many situations, from valvular to congenital heart disease, and whenever there is a mismatch between symptoms during stress and findings at rest. Increasing societal concern regarding cost, environment and radiation risks of medical imaging will lead to a preferential application of ultrasound over competing techniques, due to its unsurpassed versatility, portability, absence of radiation, and low cost’.14 They are telling us, make it easier, make it simple, make it available for many, but make it! Conflict of interest: None declared.