Decreased cardiac mortality with nicorandil in patients with ischemic heart failure

Cardioprotective and Antianginal Efficacy of Nicorandil: A Comprehensive Review

ABSTRACT

Angina pectoris remains a significant burden despite advances in medical therapy and coronary revascularization. Many patients (up to 30%) with angina have normal coronary arteries, with coronary microvascular disease and/or coronary artery vasospasm being major drivers of the myocardial demand-supply mismatch. Even among patients revascularized for symptomatic epicardial coronary stenosis, recurrent angina remains highly prevalent. Medical therapy for angina currently centers around 2 disparate goals, viz secondary prevention of hard clinical outcomes and symptom control. Vasodilators, such as nitrates, have been first-line antianginal agents for decades, along with beta-blockers and calcium channel blockers. However, efficacy in symptoms control is heterogenous, depending on underlying mechanism(s) of angina in an individual patient, often necessitating multiple agents. Nicorandil (NCO) is an antianginal agent first discovered in the late 1970s with a uniquely dual mechanism of action. Like a typical nitrate, it mediates medium-large vessel vasodilation through nitric oxide. In addition, NCO has adenosine triphosphate (ATP)-dependent potassium channel agonist activity (K ATP ), mediating microvascular dilatation. Hence, it has proven effective in both coronary artery vasospasm and coronary microvascular disease, typically challenging patient populations. Moreover, emerging evidence suggests that cardiomyocyte protection against ischemia through ischemic preconditioning may be mediated through K ATP agonism. Finally, there is now fairly firm evidence in favor of NCO in terms of hard event reduction among patients with stable coronary artery disease, following myocardial infarction, and perhaps even among patients with congestive heart failure. This review aims to summarize the mechanism of action of NCO, its efficacy as an antianginal, and current evidence behind its impact on hard outcomes. Finally, we review other cardiac and emerging noncardiac indications for NCO use.

Nicorandil Exerts Anticonvulsant Effects in Pentylenetetrazol-Induced Seizures and Maximal-Electroshock-Induced Seizures by Downregulating Excitability in Hippocampal Pyramidal Neurons

N-(2-hydroxyethyl) nicotinamide nitrate (nicorandil), a nitrate that activates adenosine triphosphate (ATP)-sensitive potassium (K_ATP) channels, is generally used in the treatment of angina and offers long-term cardioprotective effects. It has been reported that several K_ATP channel openers can effectively alleviate the symptoms of seizure. The purpose of this study was to investigate the improvement in seizures induced by nicorandil. In this study, seizure tests were used to evaluate the effect of different doses of nicorandil by analysing seizure incidence, including minimal clonic seizure and generalised tonic-clonic seizure. We used a maximal electroshock seizure (MES) model, a metrazol maximal seizure (MMS) model and a chronic pentylenetetrazol (PTZ)-induced seizure model to evaluate the effect of nicorandil in improving seizures. Each mouse in the MES model was given an electric shock, while those in the nicorandil group received 0.5, 1, 2, 3 and 6 mg/kg of nicorandil by intraperitoneal injection, respectively. In the MMS model, the mice in the PTZ group and the nicorandil group were injected subcutaneously with PTZ (90 mg/kg), and the mice in the nicorandil group were injected intraperitoneally with 1, 3 and 5 mg/kg nicorandil, respectively. In the chronic PTZ-induced seizure model, the mice in the PTZ group and the nicorandil group were injected intraperitoneally with PTZ (40 mg/kg), and the mice in the nicorandil group were each given 1 and 3 mg/kg of PTZ at a volume of 200 nL. Brain slices containing the hippocampus were prepared, and cell-attached recording was used to record the spontaneous firing of pyramidal neurons in the hippocampal CA1 region. Nicorandil (i.p.) significantly increased both the maximum electroconvulsive protection rate in the MES model and the seizure latency in the MMS model. Nicorandil infused directly onto the hippocampal CA1 region via an implanted cannula relieved symptoms in chronic PTZ-induced seizures. The excitability of pyramidal neurons in the hippocampal CA1 region of the mice was significantly increased after both the acute and chronic administration of PTZ. To a certain extent, nicorandil reversed the increase in both firing frequency and proportion of burst spikes caused by PTZ (P < 0.05). Our results suggest that nicorandil functions by downregulating the excitability of pyramidal neurons in the hippocampal CA1 region of mice and is a potential candidate for the treatment of seizures.

Renal Venous Stasis Index Reflects Renal Congestion and Predicts Adverse Outcomes in Patients With Heart Failure

Background

It has been recently reported that the renal venous stasis index (RVSI) assessed by renal Doppler ultrasonography provides information to stratify pulmonary hypertension that can lead to right-sided heart failure (HF). However, the clinical significance of RVSI in HF patients has not been sufficiently examined. We aimed to examine the associations of RVSI with parameters of cardiac function and right heart catheterization (RHC), as well as with prognosis, in patients with HF.

Methods

We performed renal Doppler ultrasonography, echocardiography and RHC in hospitalized patients with HF (n = 388). RVSI was calculated as follows: RVSI = (cardiac cycle time-venous flow time)/cardiac cycle time. The patients were classified to three groups based on RVSI: control group (RVSI = 0, n = 260, 67%), low RVSI group (0 &lt; RVSI ≤ 0.21, n = 63, 16%) and high RVSI group (RVSI &gt; 0.21, n = 65, 17%). We examined associations of RVSI with parameters of cardiac function and RHC, and followed up for cardiac events defined as cardiac death or worsening HF.

Results

There were significant correlations of RVSI with mean right atrial pressure (mRAP; R = 0.253, P &lt; 0.001), right atrial area (R = 0.327, P &lt; 0.001) and inferior vena cava diameter (R = 0.327, P &lt; 0.001), but not with cardiac index (R = −0.019, P = 0.769). During the follow-up period (median 412 days), cardiac events occurred in 60 patients. In the Kaplan–Meier analysis, the cumulative cardiac event rate increased with increasing RVSI (log-rank, P = 0.001). In the multivariate Cox proportional hazard analysis, the cardiac event rate was independently associated with RVSI (high RVSI group vs. control group: hazard ratio, 1.908; 95% confidence interval, 1.046–3.479, P = 0.035).

Conclusion

RVSI assessed by renal Doppler ultrasonography reflects right-sided overload and is associated with adverse prognosis in HF patients.

Pre- and Post-Conditioning of the Heart: An Overview of Cardioprotective Signaling Pathways

Since the discovery of ischemic pre- and post-conditioning, more than 30 years ago, the knowledge about the mechanisms and signaling pathways involved in these processes has significantly increased. In clinical practice, on the other hand, such advancement has yet to be seen. This article provides an overview of ischemic pre-, post-, remote, and pharmacological conditioning related to the heart. In addition, we reviewed the cardioprotective signaling pathways and therapeutic agents involved in the above-mentioned processes, aiming to provide a comprehensive evaluation of the advancements in the field. The advancements made over the last decades cannot be ignored and with the exponential growth in techniques and applications. The future of pre- and post-conditioning is promising.

Protective Effects of Nicorandil on Cardiac Function and Left Ventricular Remodeling in a Rat Model of Ischemic Heart Failure

Nicorandil, the first clinically applied ATP-sensitive K⁺ channel (K⁺ATP) opener with nitrate property, has demonstrated cardioprotective effects in patients with multiples of heart diseases. However, it is unknown whether nicorandil has effects on left ventricular (LV) remodeling in rats with ischemic heart failure and the potential mechanisms remain unclear. In this study, we investigated the effects of nicorandil on cardiac function, LV remodeling, and Bax expression in myocardium of LV in rats with ischemic heart failure. We found that nicorandil could improve not only the general condition, but also the cardiac function in rats with ischemic heart failure. The data also demonstrated that nicorandil reduced the hypertrophy and fibrosis of LV in rats with ischemic heart failure. Furthermore, nicorandil suppressed the protein level of Bax expression in LV myocardium. Taken together, these results suggest that nicorandil exerts its cardioprotective effect and improves LV remodeling in rats with ischemic heart failure. The mechanism might be relative to the inhibitory effect of nicorandil on the protein level of Bax expression in LV myocardium.

Myocardial Protective Effects of Nicorandil on Rats with Type 2 Diabetic Cardiomyopathy

Background

Diabetic cardiomyopathy (DCM) is a common but underestimated cause of heart failure in patients with diabetes. This study investigated the myocardial-protective effects of nicorandil (Nic) on rats with DCM.

Material/Methods

A total of forty-seven 180–220 g male Wistar rats were randomly divided into 4 groups: a control group (control, n=8), a DCM group (DCM, n=13), a nicorandil-pretreated DCM group (Nic₁, n=13), and a nicorandil-treated DCM group (Nic₂, n=13). A rat model of type 2 diabetes was induced by high-fat and high-sugar diet and intraperitoneal injection of streptozotocin (STZ). Nicorandil (3 mg/kg/d) was orally administrated to rats in the Nic₁ group starting at week 4. Nicorandil (3 mg/kg/d) was orally administrated only after the induction of diabetes in the Nic₂ group. The serum lipoids, plasma glucose, insulin levels, heart weight index, serum creatine kinase (CK), lactate dehydrogenase (LDH) levels, superoxide dismutase (SOD) activity, and malondialdehyde (MDA) were analyzed in all groups.

Results

The DCM group showed increased heart weight index, serum LDH, CK, and MDA content and decreased serum SOD activity, as compared with the control group (P<0.05). The DCM-induced increases in heart weight index, serum LDH, CK, and MDA content and decrease in serum SOD activity were attenuated in both Nic₁ and Nic₂ groups (P<0.05). However, there was no significant difference between Nic₁ and Nic₂ groups (P>0.05).

Conclusions

Nicorandil has protective effects on cardiac hypertrophy in DCM rats through increased SOD activity and decreased MDA content. Therefore, nicorandil may be a therapeutic method for diabetic patients with DCM.

Inotropic Effects of Nicorandil on Cardiac Contractility Assessed by Left Ventricular Pressure-Volume Relationship Analyses in Anesthetized Monkeys

Nicorandil is a representative antianginal drug that has dual properties of a nitrate and adenosine triphosphate-sensitive potassium (KATP) channel agonist; however, its effects on integrated cardiac function have not been fully understood. This study was conducted to clarify the functional, hemodynamic, and electrophysiological effects of nicorandil using ventricular pressure-volume loop analysis in isoflurane-anesthetized monkeys. Nicorandil was given intravenously at therapeutic doses of 0.2 and 2 mg/kg over 10 minutes to cynomolgus monkeys (n = 5) with a pause of 10 minutes between the 2 doses. Nicorandil at 0.2 mg/kg caused decreases in systemic blood pressure and left ventricular end-diastolic pressure by its vasodilating action. Nicorandil at 2 mg/kg also exhibited positive inotropic action demonstrated by increased slopes of preload recruitable stroke work relationship, which is a load-independent inotropic parameter. In load-dependent inotropic parameters, positive inotropy of nicorandil was also indicated by the shortened QA interval and increased contractility index; however, significant changes were not observed in the maximal upstroke velocity of left ventricular pressure. Moreover, reflex tachycardia accompanied by shortening of QT/QTc intervals was observed. Overall, the isoflurane-anesthetized monkey model with pressure-volume loop analysis revealed cardiac variables of nicorandil, including a positive inotropy contributable to cardiac performance in addition to its vasodilatory effect. These findings provide useful information when considering the prescription of nicorandil in patients.