Global myocardial contractile reserve assessed by high-dose dobutamine stress echocardiography predicts response to the cardiac resynchronization therapy

The Utility of Low-Dose-Dobutamine Stress Echocardiography in Patients with Heart Failure with Reduced Ejection Fraction: An Update

Despite significant advancements in medical therapy, heart failure with reduced ejection fraction (HFrEF) continues to be a significant cause of death and disability. Reversible ischaemic left ventricular dysfunction due to viable myocardium is one such contributing factor. In these cases, coronary revascularization has shown promise in improving left ventricular function and prognosis. For patients with HFrEF and wide QRS, cardiac resynchronization therapy (CRT) is an effective option to address electromechanical dyssynchrony. However, approximately 30% of patients do not respond positively to CRT, highlighting the need to refine candidate selection for this treatment. In some patients with reduced HFrEF, there is a condition known as classical low-flow, low-gradient aortic stenosis (AS) that may be observed. This condition is characterized by a low transaortic flow, which leads to reductions in both the transaortic mean gradient and aortic valve area. Decision-making regarding revascularization, CRT, and pharmacological treatment play a crucial role in managing HFrEF. Cardiac imaging can be valuable in guiding decision-making processes and assessing the prognosis of patients with HFrEF. Among the imaging modalities, dobutamine stress echocardiography has come a long way in establishing itself as a feasible, safe, effective, relatively cheap non-invasive technique. The aim of this review is to explore the current literature on the utility of low-dose stress echocardiography in diagnosing and prognosticating patients with HFrEF.

Stress ECHO beyond coronary artery disease. Is it the holy grail of cardiovascular imaging?

Stress echocardiography (SE) is a very useful method in clinical practice, because it offers important information of both the patient's functional status and hemodynamic changes during stress. Therefore, SE provides strong diagnostic and prognostic data in a wide spectrum of cardiovascular diseases. This review summarizes the clinical applications of SE in conditions beyond coronary artery disease (CAD) and highlights practical recommendations and key issues for each condition that need further investigation. SE is an established method for the evaluation of symptomatic and asymptomatic patients with valvular heart disease (VHD) and cardiomyopathies, and provides important information regarding prognosis and management of patients with congenital heart disease, pulmonary hypertension or diastolic dysfunction. Moreover, when one or multiple VHD and cardiomyopathy or CAD coexist in one patient, SE is a very useful clinical tool for the evaluation of etiology and symptomatology.

Current role of echocardiography in cardiac resynchronization therapy

Cardiac resynchronization therapy (CRT) is an established treatment for patients with heart failure and left ventricular systolic dysfunction. Patients are usually assessed by echocardiography, which provides a number of anatomical and functional information used for cardiac dyssynchrony assessment, prognostic stratification, identification of the optimal site of pacing in the left ventricle, optimization of the CRT device, and patient follow-up. Compared to other cardiac imaging techniques, echocardiography has the advantage to be non-invasive, repeatable, and safe, without exposure to ionizing radiation or nefrotoxic contrast. In this article, we review current evidence about the role of echocardiography before, during, and after the implantation of a CRT device.

The Role of Echocardiography in the Optimization of Cardiac Resynchronization Therapy: Current Evidence and Future Perspectives

Background:

Cardiac resynchronization therapy (CRT) has become a mainstay in the management of heart failure. Up to one-third of patients who received resynchronization devices do not experience the full benefits of CRT. The clinical factors influencing the likelihood to respond to the therapy are wide QRS complex, left bundle branch block, female gender, non-ischaemic cardiomyopathy (highest responders), male gender, ischaemic cardiomyopathy (moderate responders) and narrow QRS complex, non-left bundle branch block (lowest, non-responders).

Objective:

This review provides a conceptual description of the role of echocardiography in the optimization of CRT.

Method:

A literature survey was performed using PubMed database search to gather information regarding CRT and echocardiography.

Results:

A total of 70 studies met selection criteria for inclusion in the review. Echocardiography helps in the initial selection of the patients with dyssynchrony, which will benefit the most from optimal biventricular pacing and provides a guide to left ventricular (LV) lead placement during implantation. Different echocardiographic parameters have shown promise and can offer the possibility of patient selection, response prediction, lead placement optimization strategies and optimization of device configurations.

Conclusion:

LV ejection fraction along with specific electrocardiographic criteria remains the cornerstone of CRT patient selection. Echocardiography is a non-invasive, cost-effective, highly reproducible method with certain limitations and accuracy that is affected by measurement errors. Echocardiography can assist with the identification of the appropriate electromechanical substrate of CRT response and LV lead placement. The targeted approach can improve the haemodynamic response, as also the patient-specific parameters estimation.

Left ventricular contractile reserve by stress echocardiography as a predictor of response to cardiac resynchronization therapy in heart failure: a systematic review and meta-analysis

Background

The presence of left ventricular contractile reserve (LVCR) during stress echo (SE) may provide favorable response to cardiac resynchronization therapy (CRT) in heart failure patients. The aim of the study was to perform a meta-analysis of available SE data in this set of patients.

Methods

From a Pubmed and Advance Google Scholar database web based search scan up to December 2016, we initially identified 5906 records. From this initial set, we removed that did not include SE and duplicate studies. We assessed for eligibility 71 full-text articles assessed for eligibility, and 60 of them did not meet the inclusion criteria as follow: 1) heart failure patients with NYHA class III and IV, depressed ejection fraction (EF <35%) and QRS duration ≥120 ms at study entry; 2) SE with assessment of LVCR; 3) Follow-up data. LVCR during SE was identified as reduction in wall motion score index and/or an increase in EF.

Results

Eleven studies with 861 patients (mean age 67 ± 9 years, ejection fraction 25 ± 6%) were included in the meta-analysis. The type of stress was either exercise (n = 2) or dobutamine (n = 9), the latter with low-dose (10 mcg) in two, intermediate-dose (20 mcg) in five, and high-dose (40 mcg) protocol in two studies. LVCR was detected in 555 patients (63%) and CRT-response was present in 584 (66%). The overall odds ratio for LVCR to predict a favorable CRT response was 2.06 (95%, CI 1.70–2-43), Z score: 11.055, p < 0.001.

Conclusion

The presence of LVCR during SE with either dobutamine or exercise is associated with a greater chance of response to CRT. This parameter is now ready to be tested in a prospective multicenter trial to select patients more likely to benefit from CRT.

Stress echocardiography: what is new and how does it compare with myocardial perfusion imaging and other modalities?

Cardiovascular disease is a leading cause of morbidity and mortality, and noninvasive strategies to diagnose and risk stratify patients remain paramount in the evaluative process. Stress echocardiography is a well-established, versatile, real-time imaging modality with advantages including lack of radiation exposure, portability, and affordability. Innovative techniques in stress echocardiography include myocardial contrast echocardiography, deformation imaging, three-dimensional (3D) echocardiography, and assessment of coronary flow reserve. Myocardial perfusion imaging with single-photon emission computed tomography (SPECT) or positron emission tomography (PET) are imaging alternatives, and stress cardiac magnetic resonance imaging and coronary computed tomography (CT) angiography, including CT perfusion imaging, are emerging as newer approaches. This review will discuss recent and upcoming developments in the field of stress testing, with an emphasis on stress echocardiography while highlighting comparisons with other modalities.