Heart failure (HF) is a pernicious medical syndrome which is growing in prevalence as the global population ages, while outcomes in acute heart failure (AHF) remain dire, with mortality approximating 10-30% at 1-year post hospital admission. Clearly delineating AHF subcategories may aid in the assessment and treatment of patients, allowing clinicians to better elucidate the underlying mechanisms, whilst better prognostication may help physicians to appropriately escalate therapies in AHF. This thesis presents data from the Mitral Regurgitation in Acute Heart Failure (MRAHF) study. This thesis hypothesised that myocardial deformation imaging in standard clinical conditions was both feasible and would demonstrates substantial differences in global longitudinal strain and strain rate values between heart failure subcategories, and that a novel prognostic tool for AHF could be produced using only data available upon admission. When compared to the EuroHeart Survey II (EHSII) cohort, a large prospective observational cohort of AHF, the MRAHF cohort is older (79.0 years ± 11.5 versus 69.9 years ± 12.5, p<0.00001), with reduced rates of hypertension (55.0% vs 62.5%, p <0.005), ischaemic heart disease (37.8% vs 53.6%, p<0.00001) and COPD (14.3% vs 19.3%, p<0.05), but with similar in-hospital mortality outcomes (4.9% vs 6.7%, p<0.15). Peak systolic strain (PSS) varied significantly and substantially between the AHF subcategories - HFrEF, HFmrEF and HFpEF – in all cardiac regions assessed in the echocardiographic 4, 2 and 3 chamber views using standard clinical frame rates. The difference was most clearly seen when assessing global longitudinal peak systolic strain (GLS) where median GLS was - -6.62% (-4.41 – -8.83), -9.03% (-6.28 – -11.78) and -13.12% (-10.02 – -16.22) in HFrEF, HFmrEF and HFpEF respectively, p<0.0001 between all subgroups. The above was also seen for peak systolic strain rate (PSSR), where PSSR varied substantially and significantly between subcategories in all myocardial regions assessed. This difference was most marked for global longitudinal peak systolic strain rate (GLSR); -0.48 S-1 (-0.34 – -0.62), -0.66 S-1 (-0.49 – -0.83) and -0.87 S-1 (-0.70 – -1.04) respectively, p<0.00001 between all groups. These data demonstrate the feasibility and potential utility of stratifying AHF patients according to less load-dependent measures of systolic function such as GLS and GLSR. iv Using demographic and biochemical data collected at the point of patient admission for AHF, a prognostic risk scoring system was created using binary logistic regression methods. Each variable was assigned one point in the score, and total scores were grouped together to produced low risk (0-2) medium risk (3-4) and high risk (≥5) groups. Significantly different 6-month mortality rates were seen between risk groups - 4.9%, 25.3% and 49.2% respectively, p<0.0001. The C-index for this risk score was 0.746 (0.695 – 0.798) indicating a test with fair predictive accuracy. A further prognostic model was created which included echocardiographic variables. In this model age ≥80 was assigned two points due to an odds ratio approximately double that of the other variables. All other variables were assigned one point and the total score were grouped together to produce low risk (0-3), medium risk (4-5) and high risk (6-10). Significantly different 6-month mortality rates were seen between risk groups – 4.7%, 23.7% and 54.2% respectively, p<0.0001. The C-index for this risk score was 0.804 (0.758-0.849) indicating a test with good predictive accuracy. These data demonstrate the feasibility of producing and using such a risk scoring tool at the point of admission to hospital.
|Publication status||Published - 23 Oct 2019|