Cardiovascular magnetic resonance imaging in patients with chronic heart failure

Abstract

Heart failure (HF) is a progressive and complex syndrome with poor prognosis, characterized by a wide array of cardiac structural and functional abnormalities. Patients are typically categorized according to left ventricular ejection fraction (LVEF), with reduced ejection fraction defined as LVEF<40% (HFrEF), mid-range LVEF in the span of 40%-49% (HFmrEF) and those with heart failure with preserved LVEF≥50% (HFpEF). Since LVEF has poor prognostic value in patients with HF and presents unsatisfactory diagnostic value in patients with HFpEF, more insightful imaging biomarkers have been intensively investigated. Global longitudinal strain (GLS) conventionally measured at the endocardium has been shown to be superior to LVEF in distinguishing patients with HFpEF patients from healthy subjects and predicting adverse outcomes in patients with acute HF. However, the potential incremental value of layer-specific strain has not been investigated in patients with HF. As HF tends to be progressive, cardiac imaging is a common surveillance strategy for patients with chronic HF and LVEF still the predominant biomarker of interest that physicians pay attention to in serial testing. Prior imaging studies of HF have often been limited to single time-points. In particular, there is a lack of literature evaluating the temporal changes in cardiac structure and function and their clinical relevance in patients with chronic HF. Notably, patients with chronic stable HF generally have a progressive course with high morbidity and mortality. Thus far, no study has investigated longitudinal cardiac changes in patients with stable HF. While there have been advances in the treatment of HF, overall prognosis remains poor. Earlier identification of HF patients with higher risk to develop long-term adverse outcome helps physicians initiate, intensify and adjust the management strategy. The majority of the validated risk predicting models predominantly focus on clinical information including demographics, disease history and risk factors. As cardiac imaging plays an essential role in evaluating patients with HF, it is important to incorporate valuable imaging biomarkers in the risk predicting model. To our knowledge, there has been no validated imaging predictive model in patients with HF. Cardiac magnetic resonance (CMR) is the gold standard for non-invasive cardiac measures. Its high accuracy and reproducibility make CMR well suited for delineating epi- and endomyocardial border in order to analyze layer-specific strains, and identify temporal changes during serial testing. Furthermore, it enables us to comprehensively collect state-of-the-art information on cardiac function, volume and tissue characterization as a one-stop test. Our studies aim to utilize CMR in patients with chronic heart failure to: 1) investigate the diagnostic and prognostic value of CMR-derived layer-specific strain; 2) evaluate the prevalence and prognostic significance of serial changes in cardiac structure and function ; 3) develop and validate comprehensive predictive models incorporating clinical and imaging data.