Platelet-derived growth factor-AB improves scar mechanics and vascularity after myocardial infarction

Therapies that target scar formation after myocardial infarction (MI) could prevent ensuing heart failure or death from ventricular arrhythmias. We have previously shown that recombinant human platelet-derived growth factor-AB (rhPDGF-AB) improves cardiac function in a rodent model of MI. To progress clinical translation, we evaluated rhPDGF-AB treatment in a clinically relevant porcine model of myocardial ischemia-reperfusion. Thirty-six pigs were randomized to sham procedure or balloon occlusion of the proximal left anterior descending coronary artery with 7-day intravenous infusion of rhPDGF-AB or vehicle. One month after MI, rhPDGF-AB improved survival by 40% compared with vehicle, and cardiac magnetic resonance imaging showed left ventricular (LV) ejection fraction improved by 11.5%, driven by reduced LV end-systolic volumes. Pressure volume loop analyses revealed improved myocardial contractility and energetics after rhPDGF-AB treatment with minimal effect on ventricular compliance. rhPDGF-AB enhanced angiogenesis and increased scar anisotropy (high fiber alignment) without affecting overall scar size or stiffness. rhPDGF-AB reduced inducible ventricular tachycardia by decreasing heterogeneity of the ventricular scar that provides a substrate for reentrant circuits. In summary, we demonstrated that rhPDGF-AB promotes post-MI cardiac wound repair by altering the mechanics of the infarct scar, resulting in robust cardiac functional improvement, decreased ventricular arrhythmias, and improved survival. Our findings suggest a strong translational potential for rhPDGF-AB as an adjunct to current MI treatment and possibly to modulate scar in other organs.

Association Between Plasma Neutrophil Gelatinase-Associated Lipocalin and Cardiac Disease Hospitalizations and Deaths in Older Women

Background

Neutrophil gelatinase‐associated lipocalin (NGAL) or lipocalin 2 may promote atherosclerosis and plaque instability leading to increased risk of cardiac events. We investigated the relationships between plasma NGAL, cardiovascular disease biomarkers, and long‐term cardiac events.

Methods and Results

The study population consisted of 1131 ambulant older white women (mean age 75 years) without clinical coronary heart disease (CHD) and measures of plasma NGAL in the Perth Longitudinal Study of Ageing Women with 14.5‐year CHD and heart failure hospitalizations or death (events) captured using linked records. Over 14.5 years, 256 women had CHD events, while 118 had heart failure events. Per SD increase in log‐transformed NGAL there was a 35% to 37% increase in relative hazards for CHD and heart failure events in unadjusted analyses, which remained significant after adjustment for conventional risk factors for CHD events (hazard ratio 1.29, 95% CI 1.13–1.48, P<0.001) but not heart failure (P>0.05). Women in the highest 2 quartiles of NGAL had higher relative hazards for CHD events compared with women in the lowest quartile hazard ratio 1.61, 95% CI 1.08–2.39, P=0.019 and hazard ratio 1.97, 95% CI 1.33–3.93, P=0.001, respectively. These associations were independent of high‐sensitivity cardiac troponin I, homocysteine, and estimated renal function. NGAL correctly reclassified 1 in 4 women who sustained a CHD event up in risk and 1 in 10 women without CHD events down in risk.

Conclusions

NGAL was associated with increased risk of long‐term CHD events, independent of conventional risk factors and biomarkers. These findings provide mechanistic insight into the role of NGAL with cardiac events.

New Developments in Cardiac Regeneration

Numerous pharmacological and device therapies have improved adverse cardiac remodelling and mortality in heart failure. However, none are able to regenerate damaged cardiac tissue. Stem cell based therapies using multipotent (adult) stem cells and pluripotent stem cells are new approaches that could potentially achieve the elusive goal of true cardiac regeneration. Over the past two decades, various stem cell based approaches have been shown to improve left ventricular function in pre-clinical animal models. Promising results rapidly led to clinical trials, initially using bone marrow-derived mononuclear cells, then mesenchymal stromal cell populations and, more recently, progenitor cells from the adult heart itself. These have been shown to be safe and have advanced our understanding of potential suitable recipients, cell delivery routes, and possible mechanisms of action. However, efficacy in these trials has been inconsistent. Human pluripotent stem cells (hPSCs) are another potential source of stem cells for cardiac regeneration. They could theoretically provide an unlimited source of cardiomyocytes or cardiac progenitors. Pre-clinical studies in both small and large animal models have shown robust engraftment and improvements in cardiac function. The first clinical trial using hPSC-derived cardiac derivatives has now commenced and others are imminent. In this brief review article, we summarise recent developments in stem cell therapies aimed at cardiac regeneration, including discussion of types of cell and non-cell-based strategies being explored.

Evidence-based management of heart failure in clinical practice: a review of device-based therapy use

BACKGROUND

Heart failure is a growing health issue and is associated with significant mortality risk. Device therapy is efficacious in preventing sudden death in patients with heart failure; however, this evidence comes from rigorous clinical trials. It is unclear how device therapy is utilized in 'real-world' practice. The primary objective was to characterize patterns of device use in patients with heart failure at risk of sudden death and to identify barriers to guideline-driven prescription of implantable cardioverter-defibrillators.

METHODS

We report a cross-sectional study of patients attending general cardiology clinic over a 3-month period.

RESULTS

Of 1003 consecutive patients attending the cardiology clinic, 176 had heart failure. Of these, 66 were potentially eligible for device therapy, but only 16 of these had actually undergone device implantation. Potentially eligible non-recipients were older (P < 0.001), more likely to have ischaemic cardiomyopathy (P= 0.002), less likely to be prescribed spironolactone (P= 0.005) or warfarin (P= 0.02), and less likely to have a widened QRS > 120 ms (P= 0.005). There was a high prevalence of underuse of evidence-based pharmacotherapies among patients with heart failure.

CONCLUSION

There is substantial underuse of device therapy in patients with heart failure. Strikingly, whereas patients with symptoms of heart failure were more likely to receive a device, those being managed for ischaemic heart disease were not. There is also a high prevalence of failure to prescribe evidence-based pharmacotherapy in a tertiary hospital general cardiology clinic. This may be explained in part by the lack of a patient database to record treatment contraindications and to alert clinicians to possible gaps in patient therapy.

Prehydration Alone is Sufficient to Prevent Contrast-induced Nephropathy after Day-only Angiography Procedures—A Randomised Controlled Trial

BACKGROUND

Contrast agents used in angiography procedures for patients with cardiovascular disease are known to cause contrast-induced nephropathy (CIN), which may be partially due to the production of nephrotoxic oxygen-free radicals. It is uncertain whether administration of intravenous (IV) anti-oxidant, N-acetylcysteine (NAC), can prevent reduction in renal function and whether this is a cost-effective approach.

METHODS

Sixty-five day-only patients with renal impairment (mean serum creatinine concentration 0.16+/-0.03 mmol/l) due to undergo coronary or peripheral angiography and/or stenting were randomly assigned to IV NAC 300 or 600 mg immediately before and after the procedure or IV fluid alone.

RESULTS

Of the 60 patients with complete data, none had acute CIN (increase in serum creatinine concentration > or = 0.044 mmol/l, 48 h after administration of contrast agent). Eight patients (13%) have demonstrated an increase in their serum creatinine concentration > or = 0.044 mmol/l 30 days after administration of contrast agent: 2/19 (11%) in the control group, 2/21 (10%) in the 600 mg NAC group and 4/20 (20%) the 300 mg NAC group (p = 0.66). The mean volumes of contrast agent used and prehydration given for each of the three groups did not differ significantly (p > 0.83). There was significant improvement in creatinine clearance within each group from baseline to 30 days (p < or = 0.03), but no significant difference between the groups at 48 h and 30 days (p > or = 0.43). Considering the cost of NAC and its administration, we estimate that this would translate to a saving of dollar 26,637 per annum.

CONCLUSION

For day-stay patients with mild-to-moderate chronic renal impairment undergoing angiography and/or intervention, prehydration alone is less complicated and more cost-effective than a combination of IV NAC (at doses used) and hydration.