Statins in non-ischaemic cardiomyopathy: an update on our current clinical and pathophysiological understanding

Atorvastatin and blood flow regulate expression of distinctive sets of genes in mouse carotid artery endothelium

Hypercholesterolemia is a well-known pro-atherogenic risk factor and statin is the most effective anti-atherogenic drug that lowers blood cholesterol levels. However, despite systemic hypercholesterolemia, atherosclerosis preferentially occurs in arterial regions exposed to disturbed blood flow (d-flow), while the stable flow (s-flow) regions are spared. Given their predominant effects on endothelial function and atherosclerosis, we tested whether (1) statin and flow regulate the same or independent sets of genes and (2) statin can rescue d-flow-regulated genes in mouse artery endothelial cells in vivo. To test the hypotheses, C57BL/6 J mice (8-week-old male, n=5 per group) were pre-treated with atorvastatin (10mg/kg/day, Orally) or vehicle for 5 days. Thereafter, partial carotid ligation (PCL) surgery to induce d-flow in the left carotid artery (LCA) was performed, and statin or vehicle treatment was continued. The contralateral right carotid artery (RCA) remained exposed to s-flow to be used as the control. Two days or 2 weeks post-PCL surgery, endothelial-enriched RNAs from the LCAs and RCAs were collected and subjected to microarray gene expression analysis. Statin treatment in the s-flow condition (RCA+statin versus RCA+vehicle) altered the expression of 667 genes at 2-day and 187 genes at 2-week timepoint, respectively (P<0.05, fold change (FC)≥±1.5). Interestingly, statin treatment in the d-flow condition (LCA+statin versus LCA+vehicle) affected a limited number of genes: 113 and 75 differentially expressed genes at 2-day and 2-week timepoint, respectively (P<0.05, FC≥±1.5). In contrast, d-flow in the vehicle groups (LCA+vehicle versus RCA+vehicle) differentially regulated 4061 genes at 2-day and 3169 genes at 2-week timepoint, respectively (P<0.05, FC≥±1.5). Moreover, statin treatment did not reduce the number of flow-sensitive genes (LCA+statin versus RCA+statin) compared to the vehicle groups: 1825 genes at 2-day and 3788 genes at 2-week, respectively, were differentially regulated (P<0.05, FC≥±1.5). These results revealed that both statin and d-flow regulate expression of hundreds or thousands of arterial endothelial genes, respectively, in vivo. Further, statin and d-flow regulate independent sets of endothelial genes. Importantly, statin treatment did not reverse d-flow-regulated genes except for a small number of genes. These results suggest that both statin and flow play important independent roles in atherosclerosis development and highlight the need to consider their therapeutic implications for both.

Atorvastatin ameliorates cardiac fibrosis and improves left ventricular diastolic function in hypertensive diastolic heart failure model rats

OBJECTIVE

Clinical studies have suggested the beneficial effects of statin therapy on diastolic heart failure. However, the mechanism of the beneficial effects of statin on diastolic heart failure remains unknown. We examined the effect of atorvastatin on the cardiac function of Dahl salt-sensitive rat, a model of hypertensive diastolic heart failure.

METHODS

Dahl salt-sensitive rats were divided into three groups: the low-salt group (given standard diet), the high-salt group (given 8% NaCl diet from 7 weeks of age), and the high-salt + atorvastatin (HS + Ato) group (given 8% NaCl diet from 7 weeks of age and atorvastatin from 17 weeks of age). We evaluated left ventricular hypertrophy (LVH), fibrosis, and function by using echocardiography and histology. We also examined the expression of molecules related to fibrosis in the hearts of Dahl salt-sensitive rats and cultured rat cardiac fibroblasts.

RESULTS

Left ventricular hypertrophy, diastolic dysfunction, and cardiac fibrosis were observed in the high-salt group. Atorvastatin ameliorated cardiac fibrosis and normalized left ventricular diastolic function without altering blood pressure. Atorvastatin also decreased the expression of heat shock protein 47 (HSP47), an essential chaperone for type 1 collagen processing, without changing in expression of transforming growth factor beta. In rat cardiac fibroblast cells, atorvastatin also reduced HSP47 level induced by transforming growth factor beta. The effect of atorvastatin was reversed by mevalonate and geranylgeranyl-pyrophosphate and mimicked by Rho kinase inhibitor.

CONCLUSION

Atorvastatin administration ameliorates cardiac fibrosis and improves left ventricular diastolic function in Dahl salt-sensitive rats. Lowering HSP47 by atorvastatin via inhibition of Rho-Rho kinase pathway is suggested as a mechanism.

Can medications be safely withdrawn in patients with stable chronic heart failure? systematic review and meta-analysis

BACKGROUND

Heart failure (HF) therapy involves use of multiple medications. There is little guidance on the safety and impact on clinical outcomes of stopping HF medications.

METHODS AND RESULTS

A comprehensive systematic search for studies of drug therapy withdrawal in HF was performed. Meta-analysis of the risk ratio (RR) was performed with the use of the Mantel-Haenszel random effects model for all-cause mortality and cardiovascular outcomes. Twenty-six studies met the inclusion criteria. Studies on withdrawal of renin-angiotensin-aldosterone system (RAAS) inhibitors and beta-blockers in HF are scarce and small, yet show relatively convincingly that such withdrawals have untoward effects on cardiac structure, symptoms, and major outcomes. Meta-analysis of 7 studies of digoxin withdrawal (2,987 participants) without background beta-blocker showed increased HF hospitalizations (RR 1.30, 95% confidence interval [CI] 1.16-1.46; P < .0001), but no impact on all-cause mortality (RR 1.00, 95% CI 0.90-1.12; P = .06) nor reduction in all-cause hospitalization (RR 1.03, 95% CI 0.98-1.09; P = .27). Diuretic withdrawal trials demonstrated an ongoing need for these agents in chronic HF. Studies in peripartum cardiomyopathy showed that medications could be successfully withdrawn after recovery.

CONCLUSION

Current evidence discourages any attempt to discontinue RAAS inhibitors or beta-blockers in patients with stable HF, regardless of clinical and/or echocardiographic status. Formal withdrawal trials of other classes are needed.