Dapagliflozin improves left ventricular myocardial longitudinal function in people with type 2 diabetes

Background/Introduction

Asymptomatic left ventricular (LV) dysfunction is highly prevalent in patients with type 2 diabetes mellitus (T2DM). Sodium-glucose cotransporter 2 (SGLT2) inhibitors have been shown to reduce all-cause mortality and hospitalisations for heart failure in patients with T2DM. The underlying mechanisms for these cardiovascular benefits are unclear. In the Dapa-LVH trial, we had previously shown that dapagliflozin treatment significantly reduces LV mass (LVM) compared to placebo in patients with T2DM and LV hypertrophy (LVH).

Purpose

The objective of this sub-study of the Dapa-LVH study was to assess whether dapagliflozin treatment improves LV myocardial longitudinal function and LV diastolic function in patients with T2DM and LVH.

Methods

We randomly assigned 66 people (mean age 67±7 years, 38 males) with T2D, LVH with a normal LV ejection fraction to receive dapagliflozin 10mg once-daily or placebo for 12 months. The primary endpoints were change in global longitudinal strain (GLS) and LV diastolic function defined as the ratio of mitral inflow E to mitral e' annual velocities assessed using echocardiography. Secondary endpoints were left ventricular and atrial volumes assessed using cardiac magnetic resonance.

Results

Dapagliflozin treatment resulted in a median increase in GLS of −1.64±2.5% vs placebo −0.2±1.8; p=0.024, with a mean difference of −1.4% (95% CI: −2.7 to −0.2). There was a trend towards a reduction left atrial area with a median change in left atrial area of the dapagliflozin group −0.5±3.75 cm2 vs placebo group 0.0±3.5 cm2; p=0.088), leading to an absolute mean difference of −1.29cm2 (95% CI: −3.01 to 0.44). There was no significant difference between dapagliflozin and placebo in E/e' and in LV volumes.

Conclusion

Dapagliflozin treatment improved LV myocardial longitudinal function which may suggests it may improve subclinical LV dysfunction.

Funding Acknowledgement

Type of funding source: Private grant(s) and/or Sponsorship. Main funding source(s): This study was funded by an Externally Sponsored Research grant from Astra Zeneca – (grant number ESR-14-10168

Day length and weather conditions profoundly affect physical activity levels in older functionally impaired people

BACKGROUND

Regular physical activity is vital for maintaining the health and independence of older people. Few objective data exist on the effect of weather on physical activity levels in this group. The objective of this study was to evaluate the effect of weather using an objective measure of physical activity.

METHODS

This was a retrospective study of 127 participants, >65 years old, who were enrolled in a previous randomised controlled trial. The main outcome was daily activity counts measured using the RT3 triaxial accelerometer over 1-week periods. These were correlated with local weather data including daily maximum temperature, sunshine, precipitation and wind speed that were obtained from the metrological office.

RESULTS

The mean age of the subjects was 78.6 years; 90/127 were female; and 720 usable daily counts were obtained for the 127 participants. The mean daily counts showed a striking seasonal variation, with maximum activity in June and minimum in February (137 557 vs 65 010 counts per day, p<0.001). Day length, mean maximum temperature and mean daily sunshine were able to explain 72.9% of the monthly variance in daily activity levels. Daily counts showed moderate correlation with day length (r = 0.358, p<0.001), maximum temperature (r = 0.345, p<0.001), duration of sunshine (r = 0.313, p<0.001) and rain (r = -0.098, p = 0.008) but not with wind speed (r = 0.093, p = 0.12). Multivariate analysis showed that day length, sunshine duration and maximum temperature were independent predictors of daily activity (adjusted R(2) = 0.16).

CONCLUSIONS

Physical activity levels among older people are much higher in summer than in winter. Day length, sunshine duration and maximum temperature have a significant influence on physical activity levels.

Could BNP screening of acute chest pain cases lead to safe earlier discharge of patients with non-cardiac causes? A pilot study

BACKGROUND

The assessment of chest pain relies on clinical assessment and markers of cell necrosis such as Troponin T (TnT). B-type natriuretic peptide (BNP) is also raised in myocardial ischaemia and therefore may be useful in deciding if acute chest pain is of cardiac origin or not.

AIM

To investigate the role of BNP in the assessment of unselected patients presenting with acute chest pain.

METHODS

A prospective observational study of 100 patients presenting with chest pain to the Acute Medical Admissions Unit was carried out. All patients had BNP and TnT levels measured. The primary outcome was categorization of chest pain as cardiac or non-cardiac. This was determined by the discharge diagnosis. BNP cutoffs were derived from a receiver operated characteristic (ROC) curve. The sensitivity, specificity, positive predictive accuracy (PPA) and negative predictive accuracy (NPA) were all calculated for BNP, TnT and for the composite of BNP and TnT.

RESULTS

Mean BNP in patients with cardiac chest pain was significantly greater than mean BNP for patients with non-cardiac chest pain (P </= 0.0001). BNP was significantly more sensitive than TnT (P = 0.003). However TnT was more specific than BNP (98% vs. 75%, P </= 0.0001). Combining BNP and TnT increased sensitivity from 55.6% to 95.6%.

CONCLUSION

Our findings suggest that BNP is more sensitive but less specific than TnT in the diagnostic assessment of acute chest pain. However, combining BNP and TnT was a very satisfactory rule out test (negative predictive accuracy 96%) for excluding chest pain that had a cardiac origin.

Spironolactone reduces brachial pulse wave velocity and PIIINP levels in hypertensive diabetic patients

AIMS

To assess whether spironolactone has beneficial effects on blood pressure (BP), N-terminal propeptide of type III procollagen (PIIINP) and pulse wave velocity (PWV) in hypertensive, type II diabetics.

METHODS

Ten patients with type II diabetes and hypertension were enrolled in a randomized, double-blind crossover study comparing 4 months' treatment with spironolactone and placebo with a 4-week washout phase. BP, PIIINP and carotid-radial PWV were measured at the end of each treatment phase.

RESULTS

Compared with placebo, spironolactone reduced systolic BP by 15.6 +/- 46.1 mmHg (P = 0.005, 95% CI 2.7-28.5 mmHg), PIIINP by 0.6 +/- 0.3 microg l(-1) (P = 0.04, 95% CI 0.02-1.1 microg l(-1)) and PWV by 0.6 +/- 0.2 m s(-1) (P = 0.008, 95% CI 0.18-1.02 m s(-1)).

CONCLUSIONS

Spironolactone is effective at reducing systolic BP and brachial artery stiffness as indicated by PWV. It also reduces PIIINP in type II diabetic patients with hypertension.

Measuring evaporation rates of laser-trapped droplets by use of fluorescent morphology-dependent resonances

Morphology-dependent resonances (MDRs) are used to measure accurately the evaporation rates of laser-trapped 1- to 2-mum droplets of ethylene glycol. Droplets containing 3 x 10(-5) M Rhodamine-590 laser dye are optically trapped in a 20-mum hollow fiber by two counterpropagating 150-mW, 800-nm laser beams. A weaker 532-nm laser excites the dye, and fluorescence emission is observed near 560 nm as the droplet evaporates. A complete series of first-order TE and TM MDRs dominates the fluorescent output. MDR mode identification sizes the droplets and provides accurate evaporation rates. We verify the automated MDR mode identification by counting fringes in a videotape of the experiment. The longitudinal spring constant of the trap, measured by analysis of the videotaped motion of droplets perturbed from the trap center, provides independent verification of the laser's intensity within the trap.

The expression and secretion of atrial natriuretic factor and brain natriuretic peptide by rat proximal tubular cells

We examined the expression of both the natriuretic peptides and natriuretic peptide receptors (NPR) in primary cultures of rat proximal tubular (RPT) cells using Northern blot assay for peptides and receptors and radioimmunoassay and immunohistochemical analysis for atrial natriuretic factor (ANF), brain natriuretic peptide (BNP), and C-type natriuretic peptide. Freshly isolated cells expressed mRNA coding for ANF, BNP, and the NPR-C. The presence of ANF and BNP in freshly isolated cells was confirmed by immunocytochemical staining. As cells approached confluence, there was a marked increase in mRNA expression for ANF and BNP. Immunocytochemical analysis and radioimmunoassay confirmed that both these peptides were co-localised in RPT cells and present in the cell supernatant. These changes in peptide expression were associated with a concurrent decrease in the expression of the NPR-C and the appearance of the NPR-A and -B. These results confirm that freshly isolated RPT cells possess the components of an autocrine natriuretic peptide system and that growth in primary culture is associated with changes in both peptide system and that growth in primary culture is associated with changes in both peptide and receptor subtype expression, raising the possibility that the endogenous production of ANF and BNP may be involved in the control of control cell growth.

Biochemical diagnosis of ventricular dysfunction in elderly patients in general practice: observational study

OBJECTIVE

To investigate the usefulness of measuring plasma concentrations of B type natriuretic peptide in the diagnosis of left ventricular systolic dysfunction in an unselected group of elderly people.

DESIGN

Observational study.

SETTING

General practice with four centres in Poole, Dorset.

PARTICIPANTS

155 elderly patients aged 70 to 84 years.

MAIN OUTCOME MEASURES

Diagnostic characteristics of plasma B type natriuretic peptide measured by radioimmunoassay as a test for left ventricular systolic dysfunction assessed by echocardiography.

RESULTS

The median plasma concentration of B type natriuretic peptide was 39.3 pmol/l in patients with left ventricular systolic dysfunction and 15.8 pmol/l in those with normal function. The proportional area under the receiver operator curve was 0.85. At a cut-off point of 18.7 pmol/l the test sensitivity was 92% and the predictive value 18%.

CONCLUSIONS

Plasma concentration of B type natriuretic peptide could be used effectively as an initial test in a community screening programme and, possibly, using a low cut-off point, as a means of ruling out left ventricular systolic dysfunction. It is, however, not a good test to "rule in" the diagnosis, and access to echocardiography remains essential for general practitioners to diagnose heart failure early.

Changes in the stress relaxation properties of peripheral nerves after transection

Changes in peripheral nerve stress relaxation after transection were measured weekly for 5 weeks in the distal stumps of sciatic nerves of 50 Sprague-Dawley rats. Each week after transection the distal stumps of the transected nerves showed decreased stress relaxation compared with the freshly transected contralateral nerves after undergoing a 10% elongation. The transected side always showed less stress relaxation at 30 minutes than the intact contralateral side (average, 24%; range, 15% to 32%). A statistically significant difference in mean stress relaxation between the cut nerves and the uncut sciatic nerves occurred for weeks 1 through 4. Week 5 demonstrated a decrease in mean stress relaxation of the experimental side compared with the contralateral control side but this was not statistically significant. Decreased stress relaxation of the distal stump results in increased tension at the suture line as the nerve gap is overcome when performing a delayed neurorrhaphy at 1 to 5 weeks after transection.

Second-harmonic pulse compression in the soliton regime

Analytical soliton solutions of the three-wave interaction equations are shown to exhibit high power conversion for a range of nonlinear materials with no satellite peaks and energy conversion close to 100%. Related numerical solutions that yield power conversion up to 10 times those of the initial waves with less than 3% energy in the small satellite peaks and high-energy efficiency are exhibited for KDP crystals; substantial compression of the fundamental pulses is observed in this case.

Atrial natriuretic factor attenuates prostaglandin E2-stimulated plasma renin activity in humans

The effect of atrial natriuretic factor (ANF) 99-126 3 or 10 pmol/kg/min on increase in plasma renin activity (PRA) stimulated by a 30-min infusion of prostaglandin E2 (PGE2) 80 ng/kg/min was studied in healthy salt-replete male volunteers. PGE2 increased PRA to approximately 230% of basal levels (p less than 0.001). Concomitant infusion of ANF 3 pmol/kg/min significantly attenuated this rise in PRA to approximately 130% of baseline values (p = 0.02, n = 10). A quantitatively similar effect was observed with ANF 10 pmol/kg/min (n = 5). We suggest, in light of previous findings, that this inhibitory effect of ANF probably represents a nonspecific action rather than a specific effect of ANF on PGE2-mediated increases in PRA.

Atrial natriuretic peptide: an endogenous factor enhancing sodium excretion in man

For many years experimental evidence has suggested the existence of a circulating factor able to enhance sodium excretion. Very recently peptides with natriuretic activity in experimental animals have been isolated from mammalian and human cardiac tissue. In order to determine whether this natriuretic activity has relevance to man we have studied the effects of an infusion of alpha-human atrial natriuretic peptide (alpha-h-ANP) in normal subjects. Sodium excretion trebled (P = less than 0.005) during the infusion of a calculated dose of 15 pmol of alpha-h-ANP min-1 kg-1 and there was an accompanying diuresis; radioimmunoassay of plasma alpha-h-ANP during the natriuresis indicated a mean peak incremental concentration of 203 +/- 78 (SEM) pmol/l. The infusion of a calculated dose of 1.5 pmol min-1 kg-1 did not affect sodium excretion. There were no haemodynamic changes and no side effects were noted.