The IONA study: preparing the myocardium for ischaemia?

The Role of Nicorandil in the Management of Chronic Coronary Syndromes in the Gulf Region

Chronic coronary syndromes (CCS) and stable angina are a growing clinical burden worldwide. This is of particular concern in the Gulf region given its high prevalence of cardiovascular risk factors, especially diabetes mellitus and smoking. Despite recommendations on the use of first- and second-line anti-anginal medication, management challenges remain. Current guidelines for pharmacologic treatment are not determined by the range of pathophysiological mechanisms of ischaemia and consequent angina, which may occur either in isolation or co-exist. In this article, we highlight the need to improve knowledge of the epidemiology of chronic coronary syndromes in the Middle East and Gulf region, and the need for studies of stratified pharmacologic approaches to improve symptomatic angina and quality of life in the large and growing number of patients with coronary artery disease from this region. We discuss the role of nicorandil, currently recommended as a second-line anti-anginal drug in CCS patients, and suggest that this may be a particularly useful add-on therapy for patients in the Gulf region.

Mitochondrial Dysfunction and Myocardial Ischemia-Reperfusion: Implications for Novel Therapies

Mitochondria have emerged as key participants in and regulators of myocardial injury during ischemia and reperfusion. This review examines the sites of damage to cardiac mitochondria during ischemia and focuses on the impact of these defects. The concept that mitochondrial damage during ischemia leads to cardiac injury during reperfusion is addressed. The mechanisms that translate ischemic mitochondrial injury into cellular damage, during both ischemia and early reperfusion, are examined. Next, we discuss strategies that modulate and counteract these mechanisms of mitochondrial-driven injury. The new concept that mitochondria are not merely stochastic sites of oxidative and calcium-mediated injury but that they activate cellular responses of mitochondrial remodeling and cellular reactions that modulate the balance between cell death and recovery is reviewed, and the therapeutic implications of this concept are discussed.

The potential use of type-5 phosphodiesterase inhibitors in coronary artery bypass graft surgery

Exaggerated vasospasm, platelet activation, and early graft occlusion are significant barriers to successful coronary artery bypass grafting (CABG). Interestingly, vascular smooth muscle and platelets are predominant sources of type-5 phosphodiesterase (PDE5) in the body, and this enzyme is specifically inhibited by PDE5 inhibitors (eg, sildenafil citrate). Together with endogenous nitric oxide, sildenafil can induce pulmonary and coronary vasodilation, precondition the myocardium, reduce platelet activation, and potentially reduce early graft occlusion. Currently, there are no published clinical trials investigating sildenafil in coronary surgery. Recent studies on the potential use of sildenafil strongly support its beneficial effects in a wide range of patients with cardiovascular diseases. Therefore, we sought to review the literature, explore the current hypothesis that the use of sildenafil in coronary surgery patients can be beneficial, and attempt to define its potential place in the setting of CABG.

Nicorandil: a review of its use in the management of stable angina pectoris, including high-risk patients

Nicorandil (Adancor, Angicor, Dancor, Nikoril [Europe], Ikorel [Europe and Oceania], Sigmart [Japan, Korea and Taiwan]) is an adenosine triphosphate (ATP)-sensitive potassium (KATP) channel agonist with nitrate-like properties used in the management of stable angina pectoris. With well established monotherapeutic antianginal activity and a beneficial effect (when added to optimal antianginal therapy) on clinical outcomes in high-risk patients with stable angina, twice-daily oral nicorandil is a useful alternative or addition to other antianginal therapy.

Nicorandil attenuates the mitochondrial Ca2+ overload with accompanying depolarization of the mitochondrial membrane in the heart

The anti-anginal drug nicorandil has been demonstrated to protect the myocardium against ischemic injury in both experimental and clinical studies. Although nicorandil seems to protect the myocardium via activation of mitochondrial ATP-sensitive K+ (mitoKATP) channels, the mechanisms underlying its cardioprotection have remained elusive. We therefore examined whether nicorandil depolarizes the mitochondrial membrane and attenuates the mitochondrial Ca2+ overload. With the use of a Nipkow confocal system, the mitochondrial Ca2+ concentration ([Ca2+]m) and the mitochondrial membrane potential (DeltaPsim) in rat ventricular myocytes were measured by loading cells with rhod-2 and JC-1 respectively. The number of cell hypercontractures resulting from mitochondrial Ca2+ overload was counted. Exposing cells to ouabain (1 mM) evoked mitochondrial Ca2+ overload and increased the intensity of rhod-2 fluorescence to 180+/-15% of baseline ( p<0.001). Nicorandil (100 microM) significantly attenuated the ouabain-induced mitochondrial Ca2+ overload (129+/-4% of baseline; p<0.001 vs. ouabain). Nicorandil decreased the DeltaPsim during application of ouabain, thereby reducing the intensity of JC-1 fluorescence to 89+/-2% of baseline ( p<0.05). Exposure of myocytes to ouabain eventually resulted in cell hypercontracture (51+/-2%). This ouabain-induced cell hypercontracture was blunted by application of nicorandil (37+/-2%, p<0.05 vs. ouabain). Moreover, these effects of nicorandil were abolished by 5-hydroxydecanoate (500 microM), a putative mitoKATP channel blocker, and by glibenclamide (10 microM), a nonselective KATP channel blocker. Our results suggest that nicorandil attenuates the matrix Ca2+ overload with accompanying depolarization of the mitochondrial membrane. Such effect might potentially be attributed to the mechanism of cardioprotection afforded by nicorandil.