Transcatheter Mitral Valve Replacement: An Update on Current Techniques, Technologies, and Future Directions.

Growing clinical data support the use of transcatheter therapies for significant mitral valve disease. Currently, edge-to-edge repair is the transcatheter treatment of choice, but many anatomies are not suitable. Transcatheter mitral valve replacement offers several potential advantages over transcatheter repair, most notably a greater and more sustained reduction in mitral regurgitation post-implantation, but also potential disadvantages. To enable the successful treatment of mitral valve disease in a wide range of patients and anatomies, we require an armory of transcatheter devices, including transcatheter mitral valve replacement systems.

Frailty in Elderly Patients Undergoing Cardiac Surgery Increases Hospital Stay and 12-Month Readmission Rate.

BACKGROUND: Cardiac surgery risk scoring systems predict operative mortality but not outcomes related to preoperative frailty. The aim of this study was to assess frailty in a cohort of older cardiac surgery patients as a predictor of postoperative outcomes. METHODS: Prospective data was collected on patients 65 years of age and older undergoing cardiac surgery between September 2015 and October 2016 at Dunedin Hospital. Frailty was assessed with the Edmonton frail scale and five-metre gait speed. The primary endpoint was length of hospital stay. Secondary outcomes included postoperative complications, major adverse events, death and 12-month readmission rate. RESULTS: Among the 96 patients, median age was 74 (interquartile range 10.5) and 65 (68%) were males. Of the sample 64 (67%) were scored as not frail, 22 (23%) as vulnerable, and 10 (10%) as frail. The median (interquartile range) postoperative days' stay were: not frail 6 (2), vulnerable 9.5 (8), and frail 15 (13). Survival analysis adjusting for EuroSCORE II, age, sex and surgery type showed that greater Edmonton Frail Scale scores were independently predictive of longer post-surgery hospital stay with a hazard ratio for discharge of 0.83 (95% confidence interval 0.76-0.91, p<0.001) per point. The Edmonton Frail Scale score was associated with the 12-month post discharge number of readmissions (adjusted incidence rate ratio 1.24 (95% confidence interval 1.13-1.37, p<0.001) per point. CONCLUSIONS: The Edmonton Frail Scale score predicts length of hospital stay post cardiac surgery and 12-month readmission rate in patients older than 65 years of age.

HIIT Improves Left Ventricular Exercise Response in Adults with Type 2 Diabetes.

Type 2 diabetes is associated with reduced left ventricular reserve. It is unclear whether exercise training improves left ventricular function in people with type 2 diabetes. PURPOSE: This study aimed to determine whether 3 months of high-intensity interval training (HIIT) improves left ventricular function during exercise in adults with type 2 diabetes. METHODS: Participants performed a V˙O2peak test and received a DXA scan and total blood volume measurement at baseline. Left ventricular end-diastolic volume (LVEDV), left ventricular end-systolic volume (LVESV), and left ventricular stroke volume (LVSV) were then measured at rest and during low- and moderate-intensity semirecumbent exercise in adults with type 2 diabetes before and after 3 months of HIIT (n = 11) or no training (control) (n = 5). The effects of HIIT were determined using repeated-measures ANOVA. RESULTS: HIIT increased V˙O2peak by approximately 15% (P < 0.002) but did not change body composition or total blood volume. LVESV decreased and LVEDV and LVSV increased from rest to moderate-intensity exercise in both groups at baseline (all P < 0.01). Three months of HIIT increased LVEDV (P = 0.008) and LVSV (P = 0.02) at all conditions, but there was no difference in controls (all P > 0.05). HIIT augmented the reduction in LVESV from rest to moderate-intensity exercise (P < 0.04), but LVESV was unchanged in controls. Increased LVEDV explained 51% of the change in LVSV after HIIT intervention. Mitral inflow parameters and mitral annular velocities were unaffected by HIIT (all P > 0.05). CONCLUSIONS: HIIT training increased the LVSV response to exercise in adults with type 2 diabetes. These data suggest that HIIT can improve LV filling and emptying during exercise and reverse early cardiac consequences of type 2 diabetes.

Impaired ventricular filling limits cardiac reserve during submaximal exercise in people with type 2 diabetes.

BACKGROUND: Attenuated increases in ventricular stroke volume during exercise are common in type 2 diabetes and contribute to reduced aerobic capacity. The purpose of this study was to determine whether impaired ventricular filling or reduced systolic ejection were responsible for the attenuated stroke volume reserve in people with uncomplicated type 2 diabetes. METHODS: Peak aerobic capacity and total blood volume were measured in 17 people with diabetes and 16 non-diabetic controls with no evidence of cardiovascular disease. Left ventricular volumes and other systolic and diastolic functional parameters were measured with echocardiography at rest and during semi-recumbent cycle ergometry at 40 and 60% of maximal aerobic power and compared between groups. RESULTS: People with diabetes had reduced peak aerobic capacity and heart rate reserve, and worked at lower workloads than non-diabetic controls. Cardiac output, stroke volume and ejection fraction were not different at rest, but increased less in people with diabetes during exercise. Left ventricular end systolic volume was not different between groups in any condition but end diastolic volume, although not different at rest, was smaller in people with diabetes during exercise. Total blood volume was not different between the groups, and was only moderately associated with left ventricular volumes. CONCLUSIONS: People with type 2 diabetes exhibit an attenuated increase in stroke volume during exercise attributed to an inability to maintain/increase left ventricular filling volumes at higher heart rates. This study is the first to determine the role of filling in the blunted cardiac reserve in adults with type 2 diabetes.

ß-Adrenergic Responsiveness in the Type 2 Diabetic Heart: Effects on Cardiac Reserve.

Type 2 diabetes (T2D) is associated with reduced cardiac reserve and aerobic capacity. Altered myocardial autonomic nervous regulation has been demonstrated in humans with diabetes (indirectly) and animal models (directly). PURPOSE: This study aimed to determine the chronotopic and inotropic response of the type 2 diabetic heart to ß-adrenergic stimulation. METHODS: Eight people with uncomplicated T2D and seven matched controls performed a dual-energy x-ray absorptiometry scan and V˙O2peak test. Plasma catecholamines were determined at rest and during peak exercise. On a second visit, HR and left ventricular contractility were assessed using echocardiography during supine rest, parasympathetic blockade (atropine), and during incremental ß-adrenergic stimulation (dobutamine). RESULTS: V˙O2peak and HR reserve were lower in T2D (P < 0.05) as expected. Both groups increased norepinephrine comparably (P = 0.23) during peak exercise; however, epinephrine increased less in the T2D group (P < 0.05). The dobutamine dose required to achieve 85% of age-predicted maximal HR was 36% higher in CON (P < 0.05). Resting HR was higher (P < 0.01) and stroke volume indexed to fat free mass was smaller (P < 0.05) in T2D. During dobutamine infusion the response (% change) in HR, end-diastolic volumeFFM, stroke volume, ejection fraction, and cardiac output were not different between the groups. However, HR was higher (P < 0.01) and end-diastolic volume indexed to fat free mass (P < 0.01), stroke volumeFFM (P < 0.01), ejection fraction (P < 0.05), and stroke work (P < 0.01) were lower in T2D. CONCLUSIONS: Although the type 2 diabetic heart worked at smaller volumes, the HR and contractile response to ß-adrenergic stimulation were unaffected by diabetes. The reduced cardiac reserve observed in uncomplicated T2D was not explained by impaired myocardial sympathetic responsiveness but may reflect changes in the loading conditions or function of the diabetic left ventricle.