Impact of Nicorandil to Prevent Reperfusion Injury in Patients With Acute Myocardial Infarction Sigmart Multicenter Angioplasty Revascularization Trial (SMART)

KATP channels are regulators of programmed cell death and targets for the creation of novel drugs against ischemia/reperfusion cardiac injury

BACKGROUND

The use of percutaneous coronary intervention (PCI) in patients with ST-segment elevation myocardial infarction (STEMI) is associated with a mortality rate of 5%-7%. It is clear that there is an urgent need to develop new drugs that can effectively prevent cardiac reperfusion injury. ATP-sensitive K+ (KATP ) channel openers (KCOs) can be classified as such drugs.

RESULTS

KCOs prevent irreversible ischemia and reperfusion injury of the heart. KATP channel opening promotes inhibition of apoptosis, necroptosis, pyroptosis, and stimulation of autophagy. KCOs prevent the development of cardiac adverse remodeling and improve cardiac contractility in reperfusion. KCOs exhibit antiarrhythmic properties and prevent the appearance of the no-reflow phenomenon in animals with coronary artery occlusion and reperfusion. Diabetes mellitus and a cholesterol-enriched diet abolish the cardioprotective effect of KCOs. Nicorandil, a KCO, attenuates major adverse cardiovascular event and the no-reflow phenomenon, reduces infarct size, and decreases the incidence of ventricular arrhythmias in patients with acute myocardial infarction.

CONCLUSION

The cardioprotective effect of KCOs is mediated by the opening of mitochondrial KATP (mitoKATP ) and sarcolemmal KATP (sarcKATP ) channels, triggered free radicals' production, and kinase activation.

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.

Reperfusion injury in acute ischemic stroke: Tackling the irony of revascularization

Reperfusion injury is an unfortunate consequence of restoring blood flow to tissue after a period of ischemia. This phenomenon can occur in any organ, although it has been best studied in cardiac cells. Based on cardiovascular studies, neuroprotective strategies have been developed. The molecular biology of reperfusion injury remains to be fully elucidated involving several mechanisms, however these mechanisms all converge on a similar final common pathway: blood brain barrier disruption. This results in an inflammatory cascade that ultimately leads to a loss of cerebral autoregulation and clinical worsening. In this article, the authors present an overview of these mechanisms and the current strategies being employed to minimize injury after restoration of blood flow to compromised cerebral territories.

Clinical outcomes of nicorandil administration in patients with acute ST-segment elevation myocardial infarction undergoing primary percutaneous coronary intervention: a systematic review and meta-analysis of randomized controlled trials

BACKGROUND

Primary percutaneous coronary intervention is the treatment of choice in ST-segment elevation myocardial infarction and no-reflow phenomenon is still an unsolved problem.

METHODS

We searched PubMed, EmBase, and Cochrane Central Register of Controlled Trials for relevant randomized controlled trials. The primary endpoint was the incidence of major adverse cardiac events and the secondary endpoint was the incidences of no-reflow phenomenon and complete resolution of ST-segment elevation.

RESULTS

Eighteen randomized controlled trials were enrolled. Nicorandil significantly reduced the incidence of no-reflow phenomenon (OR, 0.46; 95% CI, 0.36-0.59; P < 0.001; I² = 0%) and major adverse cardiac events (OR, 0.42; 95% CI, 0.27-0.64; P < 0.001; I² = 52%). For every single outcome of major adverse cardiac events, only heart failure and ventricular arrhythmia were significantly improved with no heterogeneity (OR, 0.36; 95% CI, 0.23-0.57, P < 0.001; OR, 0.43; 95% CI, 0.31-0.60, P < 0.001 respectively). A combination of intracoronary and intravenous nicorandil administration significantly reduced the incidence of major adverse cardiac events with no heterogeneity (OR, 0.24; 95% CI, 0.13-0.43, P < 0.001; I² = 0%), while a single intravenous administration could not (OR, 0.66; 95% CI, 0.40-1.06, P = 0.09; I² = 52%).

CONCLUSIONS

Nicorandil can significantly improve no-reflow phenomenon and major adverse cardiac events in patients undergoing primary percutaneous coronary intervention. The beneficial effects on major adverse cardiac events might be driven by the improvements of heart failure and ventricular arrhythmia. A combination of intracoronary and intravenous administration might be an optimal usage of nicorandil.

Effect of nicorandil treatment adjunctive to percutaneous coronary intervention in patients with acute myocardial infarction: a systematic review and meta-analysis

Objective

There is controversy whether nicorandil treatment has cardioprotective effects in patients with acute myocardial infarction (AMI) following percutaneous coronary intervention (PCI). This meta-analysis was conducted to assess the efficacy of nicorandil on functional and clinical outcomes after PCI.

Methods

Systematic databases were searched to retrieve studies that compared the effect of nicorandil with a control group in patients with AMI who underwent PCI. Outcomes related to coronary blood flow, and functional and clinical outcomes were extracted and a meta-analysis was performed. Trial sequential analysis was conducted to estimate the required sample size for statistical power.

Results

Twenty-four trials involving 2965 patients with AMI were enrolled. Pooled results showed that nicorandil treatment significantly suppressed the incidence of no-reflow phenomenon and reperfusion arrhythmia after reperfusion, improved the left ventricular ejection fraction and left ventricular end-systolic volume index, and reduced major adverse cardiovascular events and cardiovascular death. Trial sequential analysis confirmed the effect of nicorandil in reducing the incidence of no-reflow phenomenon and follow-up major adverse cardiovascular events in patients with AMI after PCI.

Conclusion

Our findings suggest that nicorandil treatment adjunctive to reperfusion therapy improves myocardial reperfusion, cardiac function, and clinical outcomes in patients with AMI.

Myocardial protective effect of intracoronary administration of nicorandil and alprostadil via targeted perfusion microcatheter in patients undergoing elective percutaneous coronary intervention: A randomized controlled trial

BACKGROUND

The aim of the study was to evaluate the efficacy of nicorandil and alprostadil on myocardial protection in patients undergoing elective percutaneous coronary intervention (PCI).

METHODS

In this prospective, single-blinded, randomized controlled study, 90 consecutive patients scheduled for elective PCI for de novo coronary lesions were assigned to the nicorandil, alprostadil, and nitroglycerin groups in a 1:1:1 ratio. Drugs were administered intracoronary via a targeted perfusion microcatheter. The primary endpoint was the thrombolysis in myocardial infarction (TIMI) myocardial perfusion frame count (TMPFC). Additionally, the corrected TIMI frame count (cTFC), TIMI myocardial perfusion grade (TMPG), and incidence of periprocedural myocardial injury (PMI) were assessed.

RESULTS

Both nicorandil and alprostadil were significantly effective in reducing TMPFC (114.6 ± 33.7 vs 93.4 ± 30.9, P = .016; 114.3 ± 34.3 vs 94.7 ± 33.3, P = .029, respectively). Similar findings were observed in the improvement of cTFC (20.3 ± 10.5 vs 13.5 ± 5.0, P = .003; 20.2 ± 7.4 vs 15.2 ± 5.2, P = .003, respectively) and percentage of TMPG 3 (100% vs 82.8%, P = .052; 83.3% vs 96.7%, P = .196, respectively); whereas, nitroglycerin produced a limited effect on TMPFC (114.4 ± 30.9 vs 112.1 ± 31.9, P = .739), cTFC (19.4 ± 7.2 vs 19.3 ± 7.2, P = .936), and percentage of TMPG 3 (86.7% vs 86.7%, P = 1.000). No significant difference was found in the incidence of PMI (16.7% vs 16.0% vs 27.6%, P = .537), though it was comparatively lower in the nicorandil and alprostadil groups. Furthermore, the intracoronary administration of nicorandil and alprostadil had a mild effect on blood pressure and heart rate.

CONCLUSIONS

The intracoronary administration of nicorandil and alprostadil via a targeted perfusion microcatheter was more effective in improving myocardial perfusion in patients undergoing elective PCI than nitroglycerin.

Effects of Intracoronary Nicorandil on Myocardial Microcirculation and Clinical Outcomes in Patients with Acute Myocardial Infarction: A Meta-Analysis of Randomized Controlled Trials

BACKGROUND

The amelioration of myocardial reperfusion in patients with acute myocardial infarction (AMI) undergoing primary percutaneous coronary intervention (PPCI) remains a significant issue.

OBJECTIVE

We conducted a meta-analysis of randomized controlled trials (RCTs) to better assess the effects of intracoronary nicorandil administration on myocardial microcirculation and clinical outcomes in these patients.

METHODS

The meta-analysis was performed according to the PRISMA (Preferred Reporting Items for Systematic Reviews and Meta-Analyses) statement. A literature search was performed in the PubMed, Embase, Cochrane Library, and Web of Science databases up to April 2019, with no time or language limitations. Pooled risk ratios (RRs) were calculated to evaluate the treatment effects.

RESULTS

Seven RCTs involving a total of 562 patients were included. Compared with control, intracoronary nicorandil significantly reduced the incidence of thrombolysis in myocardial infarction (TIMI) grade ≤ 2 (RR 0.349; 95% confidence interval [CI] 0.199-0.611; P < 0.001) and TIMI myocardial perfusion grade ≤ 2 (RR 0.611; 95% CI 0.438-0.852; P = 0.004) and was associated with higher complete ST-segment resolution rates (RR 1.326; 95% CI 1.090-1.614; P = 0.005). However, no significant benefits were observed on clinical outcomes, including death (RR 0.370; 95% CI 0.085-1.618; P = 0.187), recurrent myocardial infarction (RR 0.507; 95% CI 0.156-1.655; P = 0.261), heart failure (RR 0.528; 95% CI 0.224-1.247; P = 0.145), and target lesion/vessel revascularization (RR 1.109; 95% CI 0.553-2.224; P = 0.770).

CONCLUSIONS

Intracoronary nicorandil can significantly improve myocardial microcirculation in patients with AMI undergoing PPCI, but it failed to offer clinically significant benefits.

Nicorandil Reduces the Incidence of Contrast-Induced Nephropathy in Patients Undergoing Coronary Angiography/Intervention - Systematic Review and Meta-Analysis of Randomized Controlled Trials Including GRADE Qualification

BACKGROUND

Contrast-induced nephropathy (CIN) is associated with increased mortality and morbidity in patients undergoing coronary angiography (CAG) and percutaneous coronary intervention (PCI). We aimed to assess the latest evidence on the effect of nicorandil on the incidence of CIN in patients undergoing CAG/PCI.

METHODS

We performed a comprehensive search on topics that assessed nicorandil and CIN in CAG/PCI patients from inception up until November 2019 through several electronic databases.

RESULTS

There were a total of 1532 subjects from 7 randomized controlled trials. Nicorandil was associated with decrease CIN incidence (OR 0.31 [0.20, 0.46], p < 0.001; I²: 0%). Funnel plot was asymmetrical, indicating the risk of publication bias. Oral administration (OR 0.29 [0.18, 0.46], p < 0.001; I²: 0%) has a greater efficacy compared to intravenous route (OR 0.40 [0.17, 0.93], p < 0.001; I²: 73%). Pooled analysis of adjusted OR revealed that nicorandil reduced CIN incidence independent to other factors in the respective studies (OR 0.34 [0.16, 0.74], p = 0.006, I²: 75%). Protection against CIN (OR 0.37 [0.22, 0.61], p < 0.001; I²: 22%) was also demonstrated in renal dysfunction subgroup, pooled adjusted OR showed that the effect is independent (OR 0.30 [0.10, 0.90], p = 0.03, I²: 86%). GRADE assessment showed moderate level of certainty for the CIN reducing effect of nicorandil in both unadjusted and adjusted models with an absolute reduction of 85 per 1000 and 87 per 1000. Harbord test showed no evidence of small-study effects (p = 0.866).

CONCLUSION

Nicorandil is associated with a lower risk of CIN in patients undergoing CAG/PCI with a moderate level of certainty.

Impact of intracoronary nicorandil before stent deployment in patients with acute coronary syndrome undergoing percutaneous coronary intervention

The present study aimed to clarify the effect of bolus intracoronary nicorandil on inflammatory, oxidative and adherent indicators in patients with acute coronary syndrome (ACS) undergoing percutaneous coronary intervention (PCI). This randomized controlled trial (RCT) was performed to detect the inflammation and oxidative stress in intracoronary blood both before and after PCI. In total, 65 consecutive patients undergoing PCI were classified into a nicorandil therapy group (n=32) or a placebo group (n=33). All procedures were performed at Shandong University Qilu Hospital, China, during the period from March, 2016 to May, 2017. Intracoronary blood from patients who received nicorandil therapy during PCI showed no change in soluble CD40 ligand (sCD40L) concentration (1.86±0.08 vs. 1.90±0.09 ng/ml, P=0.12) but a significant increase was noted in the control group (1.87±0.17 vs. 2.82±0.26 ng/ml, P<0.01). This indicated a relative reduction in sCD40L level after PCI in the nicorandil group. We further demonstrated an increase in superoxide dismutase (SOD) activity (29.37±0.81 vs. 31.03±0.60 U/ml, P<0.001) and a reduction in lipid peroxidation (3.84±0.99 vs. 4.23±0.13 U/ml, P=0.001) in the nicorandil group but observed no change in the placebo group. ICAM-1 levels showed no change in the nicorandil group (69.54±6.89 vs. 72.01±8.25 ng/ml, P=0.83) but a significant increase in the control group after PCI in intracoronary blood (56.57±4.96 vs. 76.81±6.88 ng/ml, P=0.002). No changes were found in hs-CRP, TNFα and sVCAM-1 levels in coronary blood for both groups before and after PCI in ACS patients. Our findings demonstrate that intracoronary bolus nicorandil therapy has a significant effect on the inhibition of inflammatory indicators and oxidative stress in patients with ACS during PCI. This suggests a possible medical application of nicorandil for reducing inflammation and oxidative stress.

Nicorandil prior to primary percutaneous coronary intervention improves clinical outcomes in patients with acute myocardial infarction: a meta-analysis of randomized controlled trials

Background: Nicorandil prior to reperfusion by primary percutaneous coronary intervention (PCI) in patients with ST-segment elevated myocardial infarction (STEMI) has been suggested to be beneficial. However, results of previous randomized controlled trials (RCTs) were not consistent. We aimed to perform a meta-analysis to systematically evaluate the effect of periprocedural nicorandil in these patients. Methods: Related studies were obtained by searching PubMed, Embase and Cochrane's Library. Effects of perioperative nicorandil on the incidence of no-reflow phenomenon (NRP), corrected thrombolysis in myocardial infarction (TIMI) frame count (CTFC), wall motion score (WMS), left ventricular ejection fraction (LVEF), heart failure (HF) exacerbation of rehospitalization and incidence of major cardiovascular adverse events (MACE) were analyzed. Results: Eighteen RCTs with 2,055 patients were included. Treatment of nicorandil prior to PCI significantly reduced the incidence of NRP (risk ratio [RR]: 0.47, P<0.001), and reduced CTFC (weighed mean difference [WMD]: -4.54, P<0.001) immediately after PCI. Moreover, although nicorandil did not significantly affect WMS (WMD: 0.04, P=0.91), treatment of nicorandil significantly increased LVEF in STEMI patients undergoing primary PCI (WMD: 1.89%, P<0.001). In addition, nicorandil significantly reduced the risk of HF exacerbation or rehospitalization (RR: 0.44, P=0.001) and the incidence of MACE (RR: 0.68, P<0.001). Further analyses showed that effects of nicorandil on LVEF, HF exacerbation and MACE were consistent within one month after PCI and during follow-up. Conclusions: Periprocedural nicorandil improves coronary blood flow, cardiac systolic function and prognosis in STEMI patients receiving primary PCI.

Effect of sequential nicorandil on myocardial microcirculation and short-term prognosis in acute myocardial infarction patients undergoing coronary intervention

Background

This study aims to observe the effects of the intracoronary and peripheral venous administration of nicorandil for the postoperative myocardial microcirculation and short-term prognosis of ST-segment elevation myocardial infarction (STEMI) patients undergoing primary percutaneous coronary intervention (PPCI) treatment.

Methods

A total of 140 STEMI patients were divided into three groups according to different patterns of administration: sequential nicorandil group, intracoronary nicorandil group and control group. The main observation indexes included coronary blood flow and myocardial perfusion immediately after PPCI, while the secondary observation indexes included major adverse cardiovascular events (MACE) and left ventricular ejection fraction (LVEF) during the period of hospitalization.

Results

After PPCI, the difference in the proportion of patients with thrombolysis in myocardial infarction (TIMI) flow grade 3 among the three groups was statistically significant (P=0.036), where this proportion was higher in the sequential nicorandil group and intracoronary nicorandil group than in the control group (P=0.022 and P=0.047); The difference in corrected TIMI frame count (CTFC) among the three groups was statistically significant (P=0.022), where CTFC was lower in the sequential nicorandil group and intracoronary nicorandil group than in the control group (P=0.010, P=0.031); The differences in the proportion of patients with complete ST resolution (STR) and advancing of enzyme peak time to within 12 h between each two groups were statistically significant (P<0.001), where this proportion was the highest in the sequential nicorandil group; The difference in the CK-MB peak among the three groups was statistically significant (P=0.036), where the CK-MB peak was lower in the sequential nicorandil group than in the control group (P=0.012); The difference in the incidence of MACE between each two groups was statistically significant (P<0.001), where this incidence was the lowest in the sequential nicorandil group; The differences in the proportion of patients with advancing of enzyme peak time to within 14 h and LVEF among the three groups were not statistically significant (P=0.722 and P=0.284).

Conclusions

Compared with intracoronary use alone, the intracoronary and peripheral intravenous use of nicorandil can better improve myocardial microcirculation and short-term prognosis.

Intracoronary administration of nicorandil-induced cardiac arrest during primary percutaneous coronary intervention: A case report

RATIONALE

Primary percutaneous coronary intervention (PPCI) is the most effective therapy for patients with an acute ST-segment elevation myocardial infarction (STEMI). However, up to half of STEMI patients suffer from coronary microvascular dysfunction, presenting as the slow flow or no-reflow phenomenon.

PATIENTS CONCERNS

A 78-year-old man was admitted to the chest pain center with sudden chest pain and tightness for about an hour.

DIAGNOSES

Electrocardiography demonstrated ST-segment elevation in leads II, III, aVF, and third-degree atrioventricular block. Coronary angiography showed acute total occlusion in the distal right coronary artery (RCA).

INTERVENTIONS

PPCI was performed on the patient. After thrombus aspiration, a stent was placed in the distal RCA. As coronary angiography showed TIMI grade 2 flow in RCA, 6 mg nicorandil was intracoronary administrated in twice. Immediately, cardiac arrest occurred and cardiopulmonary resuscitation (CPR) was performed.

OUTCOMES

The patient survived and had a good outcome during follow-up for >6 months.

LESSONS

Up to now, there has been no case report of cardiac arrest caused by nicorandil. Although intracoronary nicorandil is one of the most commonly used methods to improve coronary flow, much more attention should be paid to side effects of nicorandil.

Effect of intracoronary agents on the no-reflow phenomenon during primary percutaneous coronary intervention in patients with ST-elevation myocardial infarction: a network meta-analysis

Background

Despite the restoration of epicardial flow after primary percutaneous coronary intervention (PPCI), myocardial reperfusion remains impaired in a significant proportion of patients. We performed a network meta-analysis to assess the effect of 7 intracoronary agents (adenosine, anisodamine, diltiazem, nicorandil, nitroprusside, urapidil, and verapamil) on the no-reflow phenomenon in patients with ST-elevation myocardial infarction (STEMI) undergoing PPCI.

Methods

Database searches were conducted to identify randomized controlled trials (RCTs) comparing the 7 agents with each other or with standard PPCI. Outcome measures included thrombolysis in myocardial infarction flow grade (TFG), ST-segment resolution (STR), left ventricular ejection fraction (LVEF), major adverse cardiovascular events (MACEs), and adverse events.

Results

Forty-one RCTs involving 4069 patients were analyzed. The addition of anisodamine to standard PPCI for STEMI was associated with improved post-procedural TFG, more occurrences of STR, and improvement of LVEF. The cardioprotective effect of anisodamine conferred a MACE-free survival benefit. Additionally, nitroprusside was regarded as efficient in improving coronary flow and clinical outcomes. Compared with standard care, adenosine, nicorandil, and verapamil improved coronary flow but had no corresponding benefits regarding cardiac function and clinical outcomes. The ranking probability for the 7 treatment drugs showed that anisodamine consistently ranked the highest in efficacy outcomes (TFG < 3, STR, LVEF, and MACEs). No severe adverse events, such as hypotension and malignant arrhythmia, were observed in patients treated with anisodamine. Network meta-regression analysis showed that age, the time to reperfusion, and study follow-up did not affect the treatment effects.

Conclusions

The intracoronary administration of anisodamine appears to improve myocardial reperfusion, cardiac function, and clinical outcomes in patients with STEMI undergoing PPCI. Given the limited quality and quantity of the included studies, more rigorous RCTs are needed to verify the role of this inexpensive and well-tolerated regimen.

Electronic supplementary material

The online version of this article (10.1186/s12872-017-0722-z) contains supplementary material, which is available to authorized users.

Nicorandil and Long-acting Nitrates: Vasodilator Therapies for the Management of Chronic Stable Angina Pectoris

Nicorandil and long-acting nitrates are vasodilatory drugs used commonly in the management of chronic stable angina pectoris. Both nicorandil and long-acting nitrates exert anti-angina properties via activation of nitric oxide (NO) signalling pathways, triggering vascular smooth muscle cell relaxation. Nicorandil has additional actions as an arterial K⁺ _ATP channel agonist, resulting in more "balanced" arterial and venous vasodilatation than nitrates. Ultimately, these drugs prevent angina symptoms through reductions in preload and diastolic wall tension and, to a lesser extent, epicardial coronary artery dilatation and lowering of systemic blood pressure. While there is some evidence to suggest a modest reduction in cardiovascular events among patients with stable angina treated with nicorandil compared to placebo, this prognostic benefit has yet to be proven conclusively. In contrast, there is emerging evidence to suggest that chronic use of long-acting nitrates might cause endothelial dysfunction and increased cardiovascular risk in some patients.

Protective effect of N-acetylcysteine activated carbon release microcapsule on myocardial ischemia-reperfusion injury in rats

With the development of science and technology, and development of artery bypass, methods such as cardiopulmonary cerebral resuscitation have been practiced in recent years. Despite this, some methods fail to promote or recover the function of tissues and organs, and in some cases, may aggravate dysfunction and structural damage to tissues. The latter is typical of ischemia-reperfusion (IR) injury. Lipid peroxidation mediated by free radicals is an important process of myocardial IR injury. Myocardial IR has been demonstrated to induce the formation of large numbers of free radicals in rats, which promotes the peroxidation of lipids within unsaturated fatty acids in the myocardial cell membrane. Markers of lipid peroxidation include malondialdehyde, superoxide dismutase and lactic dehydrogenase. Recent studies have demonstrated that N-acetylcysteine (NAC) is able to dilate blood vessels, prevent oxidative damage, improve immunity, inhibit apoptosis and the inflammatory response and promote glutathione synthesis in cells. NAC also improves the systolic function of myocardial cells and cardiac function, prevents myocardial apoptosis, protects ventricular remodeling and vascular remodeling, reduces opiomelanocortin levels in the serum and increases the content of nitric oxide in the serum, thus improving vascular endothelial function. Therefore, NAC has potent pharmacological activity; however, the relatively fast metabolism of NAC, along with its large clinical dose and low bioavailability, limit its applications. The present study combined NAC with medicinal activated carbons, and prepared N-acetylcysteine activated carbon sustained-release microcapsules (ACNACs) to overcome the limitations of NAC. It was demonstrated that ACNACs exerted greater effective protective effects than NAC alone on myocardial IR injury in rats.

Cardioprotective Effects of Nicorandil on Coronary Heart Disease Patients Undergoing Elective Percutaneous Coronary Intervention

Background

Nicorandil is a nicotinamide ester commonly prescribed for treatment of patients with coronary heart disease (CHD). In the present study, we aimed to explore the cardioprotective effects of nicorandil on CHD patients undergoing elective percutaneous coronary intervention (PCI).

Material/Methods

One hundred patients with CHD undergoing PCI were randomly divided into a control group (n=48) and a nicorandil group (n=52). Patients in the control group received traditional therapy, and while patients in the nicorandil group received nicorandil before PCI in addition to the traditional therapy. After PCI, all patients underwent coronary angiogram, and TIMI frame count (TFC) was calculated. Plasma levels of cardiac troponin I (cTnI), creatine kinase-MB (CK-MB), myeloperoxidase (MPO), and malondialdehyde (MDA) were determined before and at 6, 18, and 24 h after PCI. Moreover, systolic blood pressure (SBP), mean blood pressure (DBP), heart rate (HR), and left ventricular ejection fractions (LVEF) were recorded before and 3 months after PCI.

Results

There was a significant difference in the rate of no-reflow (P=0.036) between the 2 groups. The blood frames and levels of cTnI, CK-MB, MPO, and MDA in the nicorandil group were significantly decreased compared to the control group (all P<0.05). Moreover, administration of nicorandil markedly decreased SBP, MBP, and HR, but obviously increased LVEF at 3 months after PCI (P<0.05 or P<0.01).

Conclusions

Nicorandil exerts cardioprotective effects on CHD patients undergoing elective PCI by decreasing PCI-related myocardial injury and rate of no-reflow and improvement of LVEF.

Impact of additional intracoronary nicorandil administration during fractional flow reserve measurement with intravenous adenosine 5'-triphosphate infusion

BACKGROUND

Fractional flow reserve (FFR) is a useful index for determining the functional severity of epicardial coronary artery stenosis as an invasive physiological method. Although intravenous adenosine 5'-triphosphate (ATP) is generally used as a hyperemic agent for FFR measurement in Japan, there are some concerns about the variability of FFR measurement (short half-life, effect of caffeine, cyclic change). It is difficult to confirm sufficient maximum hyperemia after ATP infusion. Recent studies reported that nicorandil (NIC) could be an alternative to ATP as a hyperemic agent.

METHODS

Patients who underwent FFR assessments of angiographically intermediate lesions were included. All patients were asked to refrain from caffeine-containing products more than 12hours before FFR measurements. All patients first received intravenous (IV) ATP infusion (180μg/kg/min) for 3min to measure FFR (ATP-FFR). After additional intracoronary (IC) NIC administration (2mg/30s) during ATP infusion, FFR was measured again (NIC-FFR). To check cyclic change in FFR, we measured minimum and maximum FFR values during both ATP and NIC hyperemic phase.

RESULTS

In this study, 94 patients with 94 lesions were enrolled. Mean FFR value was 0.81±0.10 in ATP-FFR infusion and 0.80±0.09 in NIC-FFR, respectively. ATP-FFR and NIC-FFR had a strong correlation on the whole (r=0.92, p<0.001). In 18 patients (19%), FFR values were significantly lower in NIC-FFR than in ATP-FFR. In one-third of those patients (6%), it was possible to change therapeutic strategy from deferral range (>0.80) to interventional range (≦0.80) after NIC-FFR measurements. Cyclic change in FFR was smaller in NIC-FFR than in ATP-FFR (0.03±0.02 vs. 0.06±0.05, p<0.0001).

CONCLUSION

Additional IC NIC might be useful to confirm sufficient maximum hyperemia after IV ATP infusion in daily clinical practice. Furthermore, IC NIC could reduce cyclic change in FFR; thus, physicians might find it easier to determine FFR value during the procedure.

Preventive effect of oral nicorandil on contrast-induced nephropathy in patients with renal insufficiency undergoing elective cardiac catheterization

This study aims to investigate the preventive effect of oral nicorandil on contrast-induced nephropathy (CIN) in patients with renal insufficiency undergoing elective cardiac catheterization. A total of 240 patients with an estimated glomerular filtration rate (eGFR) of 60 mL/min or less, who were undergoing elective cardiac catheterization, were randomly assigned to nicorandil group (n = 120, 10 mg nicorandil, three times daily from 2 days before to 3 days after procedure) or control group (n = 120, matching placebo as the same method). The primary endpoint was the incidence of CIN defined as 25 % increase in serum creatinine (SCr) from baseline or 44 μmol/L (0.5 mg/dL) increase in absolute value within 72 h after exposure to contrast medium. The secondary endpoints were: (1) the changes of SCr, Cystatin-C (Cys-C) and eGFR within 72 h; (2) major adverse events (MACE) occurring within 30 days. Baseline characteristics of the patients in the two groups were similar. The incidence of CIN was significantly lower in nicorandil group compared with control group (6.67 vs. 17.5 %, P = 0.017). Compared with the control group, nicorandil group tended to have a lower SCr and Cys-C levels as well as a higher eGFR at 48 h after the procedure (all P < 0.05). There was no difference about the incidence of MACE within 30 days between nicorandil group and control group (4.16 vs. 5.83 %, P = 0.767). Multivariate logistic analysis showed that nicorandil was an independent protective factor against CIN (OR = 0.260, 95 % CI = 0.1-0.676, P = 0.006). Therefore, we concluded that oral nicorandil was associated with a decline in the incidence of CIN in patients with renal insufficiency undergoing elective cardiac catheterization.

Usefulness and safety of intracoronary administration of nicorandil for evaluating fractional flow reserve in Japanese patients

BACKGROUND

Fractional flow reserve (FFR) is useful for determining the functional significance of epicardial coronary stenosis and may facilitate clinical decision making in patients with an equivocal coronary stenosis for coronary revascularization. Therefore, determining an efficient and safe method to achieve hyperemia is important for evaluating FFR. We investigated the usefulness and safety of intracoronary bolus administration of nicorandil compared with intravenous administration of adenosine triphosphate (ATP) for evaluating FFR in Japanese patients with suspected angina pectoris.

METHODS

First, we evaluated the most appropriate hyperemic dose of nicorandil in the first 11 consecutive patients out of 101 Japanese patients. Next, we compared the FFR induced by ATP and by 2 mg of nicorandil in 130 vessels of the 101 patients.

RESULTS

FFR was measured according to nicorandil dose in 14 vessels among 11 of the 101 patients; 92.9% of the patients achieved hyperemia with 2 mg of nicorandil. The FFR values obtained with ATP were significantly correlated with those obtained with 2 mg of nicorandil (regression coefficient = 0.974, R(2) = 0.933, P < 0.001). There were no hypotension cases needing a vasopressor after ATP or nicorandil administration, and there was 1 case of transient second-degree atrioventricular block after ATP administration. The time taken to achieve hyperemia after nicorandil administration (18.9 ± 9.6 seconds) was significantly shorter than that after ATP administration (197.9 ± 23.8 seconds) (P < 0.001).

CONCLUSIONS

Intracoronary nicorandil administration is more useful than and as safe as intravenous administration of ATP for evaluating FFR in Japanese patients.

Intracoronary administration of anisodamine and nicorandil in individuals undergoing primary percutaneous coronary intervention for acute inferior myocardial infarction: A randomized factorial trial

In acute inferior myocardial infarction (AIMI), numerous conventional drugs that are used to improve the myocardial microcirculation can significantly reduce blood pressure (BP) and coronary perfusion pressure, aggravate bradyarrhythmia and cause a deterioration in the hemodynamic state of the whole body, which greatly limits the application of these drugs in clinical settings. The aim of the present study was to assess the effect of anisodamine and nicorandil regimens on the prevention of no-reflow (NR) and the amelioration of myocardial reperfusion in patients with AIMI undergoing primary percutaneous coronary intervention (PCI). A total of 104 consecutive patients with AIMI were included in this study and randomly assigned to one of four groups: A (control group), B (anisodamine group), C (nicorandil group) and D (anisodamine and nicorandil group). Patients underwent PCI via transradial artery access and the angiographic results were evaluated. Coronary diastolic BP (DBP) and systolic and mean BPs were measured by invasive catheterization. The primary end-point was a post-PCI Thrombolysis In Myocardial Infarction (TIMI) myocardial perfusion grade (TMPG) of 3. Composite end-points (mortality + new MI + target vessel revascularization) were evaluated during the hospital stay and 30 days after discharge. Following the procedure, the proportion of patients achieving TMPG 3 was significantly higher in group D than that in the other groups (P=0.014); furthermore, the incidence of a postprocedural TIMI score of 3 was the highest in group D. Three days after the procedure, the peak creatine kinase-MB and cardiac troponin I levels were the lowest and the left ventricular ejection fraction was the highest in group D. A thrombus score of 3/4 and low DBP were the independent risk factors for poor myocardial reperfusion (expressed as TMPG <3), while 2 mg anisodamine plus 2 mg nicorandil prior to PCI was protective for optimal myocardial reperfusion following the procedure. The combination of anisodamine and nicorandil can effectively ameliorate myocardial reperfusion and protect cardiac function in patients with AIMI undergoing primary PCI.

The REFLO-STEMI trial comparing intracoronary adenosine, sodium nitroprusside and standard therapy for the attenuation of infarct size and microvascular obstruction during primary percutaneous coronary intervention: study protocol for a randomised controlled trial

BACKGROUND

Microvascular obstruction (MVO) secondary to ischaemic-reperfusion injury is an important but underappreciated determinant of short- and longer-term outcome following percutaneous coronary intervention (PCI) treatment of ST-elevation myocardial infarction (STEMI). Several small studies have demonstrated a reduction in the degree of MVO utilising a variety of vasoactive agents, with adenosine and sodium nitroprusside (SNP) being most evaluated. However, the evidence base remains weak as the trials have had variable endpoints, differing drug doses and delivery. As such, the results regarding benefit are conflicting.

METHODS

The REperfusion Facilitated by LOcal adjunctive therapy in STEMI (REFLO-STEMI) trial is a multicentre, prospective, randomised, controlled, open label, study with blinded endpoint analysis: Patients presenting within 6 h of onset of STEMI and undergoing planned primary PCI (P-PCI) with TIMI 0/1 flow in the infarct-related artery (IRA) and no significant bystander coronary artery disease on angiography, are randomised into one of three groups: PCI with adjunctive pharmacotherapy (intracoronary adenosine or SNP) or control (standard PCI). All receive Bivalirudin anticoagulation and thrombus aspiration. The primary outcome is infarct size (IS) (determined as a percentage of total left ventricular mass) measured by cardiac magnetic resonance imaging (CMRI) undertaken at 48 to 72 h post P-PCI. Secondary outcome measures include MVO (hypoenhancement within infarct core) on CMRI, angiographic markers of microvascular perfusion and MACE during 1-month follow-up. The study aims to recruit 240 patients (powered at 80% to detect a 5% absolute reduction in IS).

DISCUSSION

The REFLO-STEMI study has been designed to address the weaknesses of previous trials, which have collectively failed to demonstrate whether adjunctive pharmacotherapy with adenosine and/or SNP can reduce measures of myocardial injury (infarct size and MVO) and improve clinical outcome, despite good basic evidence that they have the potential to attenuate this process. The REFLO-STEMI study will be the most scientifically robust trial to date evaluating whether adjunctive therapy (intracoronary adenosine or SNP following thrombus aspiration) reduces CMRI measured IS and MVO in patients undergoing P-PCI within 6 h of onset of STEMI.

TRIAL REGISTRATION

Trial registered 20th November 2012: ClinicalTrials.gov Identifier NCT01747174.

Cardioprotective effects of single oral dose of nicorandil before selective percutaneous coronary intervention

Objective:

Nicorandil, an opener of ATP-sensitive K+ channels, was used to treat angina in patients with coronary artery disease. In this study, we aim to investigate the cardioprotective effects of single oral dose of nicorandil in patients undergoing selective percutaneous coronary intervention (PCI).

Methods:

One hundred and thirty-eight patients with acute coronary syndrome undergoing PCI from July 2011 to October 2012 were randomly divided into control group (group 1, n=47), 10 mg oral nicorandil group (group 2, n=45), and 20 mg oral nicorandil group (group 3, n=46) about 2 hours before procedure, respectively. Cardiac troponin I (cTnI) levels were determined at 20 ~ 24 hours after PCI.

Results:

There was a significant difference in the rate of any cTnI elevation among the three groups (group 1: 36.17%, group 2: 20.00%, group 3: 15.22%, p=0.0176). With respect to the frequency of cTnI elevation ≥3 and 5×the upper limit of normal (ULN), there also had statistical difference among the three groups (17.02% in group 1, 8.89% in group 2, and 4.35% in group 3, respectively for cTnI elevation ≥3× ULN, p=0.0428; 12.77% in group 1, 6.67% in group 2, and 2.17% in group 3, respectively, for cTnI elevation ≥5× ULN, p=0.0487). Logistic regression analysis showed that LVEF (OR=0.915, 95% CI=0.853-0.981) and the use of nicorandil (OR=0.516, 95% CI=0.267-0.996) before PCI were independent protective factors of myocardial injury.

Conclusion:

Single oral dose of nicorandil (10 mg, 20 mg) 2 hours before the PCI procedure could decrease the incidence of peri-procedure myocardial injury and PCI-related myocardial infarction.

Nicorandil in patients with acute myocardial infarction undergoing primary percutaneous coronary intervention: a systematic review and meta-analysis

Background

Nicorandil, as an adjunctive therapy with primary percutaneous coronary intervention (PCI), had controversial benefits in cardioprotection in patients with acute myocardial infarction (AMI).

Methods and Results

We performed a systematic review of randomized controlled trials (RCTs) comparing treatment with nicorandil prior to reperfusion therapy with control (placebo or no nicorandil) in patients who suffered from AMI and performed primary PCI. PubMed, EMBASE and CENTRAL databases and other sources were searched without language and publication restriction. 14 trials involving 1680 patients were included into this meta-analysis. Nicorandil significantly reduced the incidence of thrombolysis in myocardial infarction (TIMI) flow grade ≤2 (risk ratio [RR], 0.57; 95% confidence interval [CI]: 0.42 to 0.79), the Timi frame count (TFC) (mean difference [MD], -5.19; 95% CI: -7.13 to -3.26), increased left ventricular ejection fraction (LVEF) (%) (MD, 3.08; 95% CI: 0.79 to 5.36), and reduced the incidence of ventricular arrhythmia (RR, 0.53; 95% CI: 0.37 to 0.76) and congestive heart failure (CHF) (RR, 0.41; 95% CI: 0.22 to 0.75). No difference in the pear creatine kinase (CK) value (MD, -290.19; 95% CI: -793.75 to 213.36) or cardiac death (RR, 0.39; 95% CI: 0.09 to 1.67) was observed.

Conclusions

Nicorandil prior to reperfusion is associated with improvement of coronary reflow as well as suppression of ventricular arrhythmia, and further improves left ventricular function in patients who suffered from AMI and underwent primary PCI. But the definite clinical benefits of nicorandil were not found, which may be due to the small sample size of the selected studies.

Comparison of the effects of nitroprusside versus nicorandil on the slow/no-reflow phenomenon during coronary interventions for acute myocardial infarction

Although slow/no-reflow is a serious problem complicating primary percutaneous coronary interventions (PCI) for acute myocardial infarction (AMI) and is associated with a poor prognosis, its efficacious treatment remains problematic. We compared the acute, in-hospital and long-term (1 year) effects of nitroprusside (NTP) with those of nicorandil (NC) on the slow/no-reflow phenomenon. Forty-nine of 442 consecutive patients with AMI who underwent primary PCI complicated by slow/no-reflow and who received intracoronary NTP (n = 25) or NC (n = 24) administration were studied. Both NTP and NC induced significant improvements in coronary flow, with increases in TIMI flow grade from 1.64 ± 0.62 to 2.74 ± 0.36 (p < 0.001) and 1.60 ± 0.86 to 2.23 ± 0.91 (p < 0.001), and in corrected TIMI frame count from 37.8 ± 15.1 to 13.7 ± 7.1 (p < 0.001) and 30.8 ± 20.7 to 19.3 ± 17.9 (p < 0.001), respectively. The degree of improvement in TIMI flow grade (post-pre/pre) and TIMI frame count (pre-post/pre) showed that NTP was more effective than NC (NTP vs. NC: 0.88 ± 0.79, 0.37 ± 0.37, p = 0.008; 0.59 ± 0.23, 0.36 ± 0.27, p = 0.003, respectively). Congestive heart failure did not tend to last beyond 3 days after onset in the NTP group, which was more than in the NC group, during hospitalization (1/25, 4/24, p = 0.143, respectively). At the 1-year follow-up, the NTP group tended to show more improvement than the NC group in MACE (5/25, 9/24, p = 0.175, respectively). NTP is a more effective treatment for slow/no-reflow associated with PCI in patients with AMI and may improve long-term clinical outcomes compared with NC.

Diannexin reduces no-reflow after reperfusion in rabbits with large ischemic myocardial risk zones

INTRODUCTION AND AIMS

In patients with ST-segment elevation myocardial infarction who receive percutaneous coronary intervention and stenting, a large zone with no-reflow is associated with adverse outcomes. During myocardial ischemia/reperfusion, phosphatidylserine (PS) translocates to the surface of endothelial cells triggering attachment of platelets and leukocytes, thus impairing microvascular blood flow. Diannexin, a recombinant dimer of the endogenous human annexin V protein, binds PS and thus inhibits the adverse effects of PS. It has been shown to attenuate postischemic reperfusion injury in several experimental models. We speculated that Diannexin would reduce no-reflow in the heart after coronary artery occlusion (CAO) and reperfusion. Rabbits received: (1) Diannexin 5 min pre-CAO (diannexin pre ischemia [DPI], 400 μg/kg, n = 17), or (2) Diannexin 5 min pre-coronary reperfusion (diannexin pre reperfusion [DPR], 400 μg/kg, n = 20), or (3) saline (Cont, n = 18), with 30 min CAO and 3 h reperfusion. In a secondary analysis, rabbits were divided into two groups based on the overall average risk zone size of 29% of the left ventricle (LV): small (<29% of LV) and large (>29% of LV).

RESULTS

Overall, risk zones and infarct size, and the no-reflow zone were similar in all groups. In hearts with large risk zones the no-reflow area was significantly smaller in both drug-treated groups (DPI, 22 ± 5% and DPR, 22 ± 3% vs. control 40 ± 3%, P < 0.006), the hemorrhagic areas were significantly smaller, and infarct size was reduced at the P < 0.06 level compared with control. In animals with small risk zones there were no significant differences. Diannexin treatment did not affect hemodynamics or LV function.

CONCLUSION

Diannexin was cardioprotective in rabbits with a severe ischemic insult. This is important, because large infarcts accompanied by no-reflow in humans are associated with increased complications. In animals with small risk zones, no significant drug effect was observed.

Antidigoxin antiserum prevents endogenous digitalis-like compound-mediated reperfusion injury via modulating sodium pump isoform gene expression

Endogenous digitalis-like compound (EDLC) is an endogenous ligand of the digitalis receptor and can remarkably inhibit Na+/K+-ATPase activity. Antidigoxin antiserum (ADA), a selective EDLC antagonist, may lessen myocardial reperfusion injury; however, the molecular mechanisms underlying the effect remain unclear. Therefore, this study investigated whether ADA may prevent myocardial reperfusion injury and modulate gene expression of sodium pump alpha isoforms. Cardiac function was examined in isolated rat hearts subjected to ischemia and reperfusion (I/R). The infarct size, EDLC level, Na+/K+-ATPase activity, and the levels of mRNA for sodium pump alpha isoforms were measured in vivo I/R rat hearts in the presence or absence of ADA. It was found that ADA significantly improved the recovery of cardiac function, decreased infarct size, decreased EDLC level, and recovered Na+/K+-ATPase activity in I/R hearts. Further studies showed that sodium pump alpha1, alpha2, and alpha3 isoform mRNA levels were significantly reduced in I/R hearts, and pretreatment with ADA induced a large increase in the mRNA levels. These results indicate that EDLC may participate in depressing Na+/K+-ATPase activity and sodium pump alpha isoform gene expression in I/R heart. It is suggested that treatment with ADA may prevent EDLC-mediated reperfusion injury via modulating sodium pump isoform gene expression.

Partial vs full coverage for tandem lesions in culprit vessel during primary coronary intervention in patients with acute ST-elevation myocardial infarction--the PERFECT-AMI study

BACKGROUND

The efficacy of partial vs full coverage for tandem lesions in the culprit vessel during primary percutaneous coronary intervention (PCI) after ST-elevation myocardial infarction (STEMI) was compared in the present study.

METHODS AND RESULTS

The 76 patients with STEMI and tandem lesions in the culprit vessel were randomized to receive stent implantation for an occluded/culprit lesion only (partial group) or complete coverage of lesions (full group). After PCI, patients in the partial group had more complete ST-segment resolution (STR) at 90 min (60.5% vs 28.9%, P=0.006), Thrombosis In Myocardial Infarction (TIMI) flow grade 3 (68.4% vs 28.9%, P=0.001), and myocardial blush grade 3 (42.1% vs 15.8%, P=0.04) than those in the full group. At 6 months, the major adverse cardiac events-free survival rate did not differ significantly between groups, but left ventricular (LV) ejection fraction was improved in the partial group. Multivariate analysis revealed pre-procedural TIMI flow grade >1 and door-to-balloon time <90 min were positively associated with complete STR at 90 min, whereas full coverage for tandem lesions was an independent factor for poor STR (odds ratio 2.58, 95% confidence interval 1.08-5.42, P=0.03).

CONCLUSIONS

For acute STEMI patients with tandem lesions in the culprit vessel, primary stenting for the occluded lesion only is beneficial in improving myocardial perfusion and LV function.

Management of 'no-reflow' complicating reperfusion therapy

No-reflow phenomenon, defined as inadequate myocardial perfusion of the adequately dilated target vessel without evidence of angiographic mechanical obstruction. It is a multifactorial, well-recognised, secondary phenomenon following reperfusion therapy such as thrombolysis or percutaneous coronary interventions (PCI). The pathophysiological mechanisms leading to the no-reflow state are incompletely understood. Embolization of the atheromatous material to the distal vasculature and intense arteriole vasospasm caused by microembolization of platelet-rich thrombi that release vasoactive agents resulting in microvascular obstructions are likely mechanisms. Current prophylaxis and management strategies are derived from limited clinical data. Intracoronary verapamil, adenosine and nitroprusside have been most frequently studied and administered for angiographic no-reflow during PCI for acute myocardial infarction or saphenous vein graft (SVG) lesions and have been shown to improve epicardial flow and microvascular perfusion. The use of distal embolic protection devices in SVG interventions also provide microvascular protection and improve clinical outcomes. However, by far the most important measures are prevention and anticipation during PCI as once no-reflow established, complete reversal of the situation may not be possible.

Myocardial protection via the coronary sinus

BACKGROUND

Recent reports on facilitated reperfusion therapy re-address interests in coronary sinus interventions (CSI). Patients in whom short time results have been reported earlier were re-evaluated, with the aim of gathering the long-term results of pressure-controlled intermittent coronary sinus occlusion (PICSO) generated in patients with acute myocardial infarction (MI) and revascularization.

METHODS AND RESULTS

Thirty-four patients with ST elevated MI, in whom complete revascularization was achieved, underwent primary thrombolysis with or without PICSO. Follow-up data from these patients were collected for at least 48 months. Immediate perioperative differences were observed for time to peak creatine kinase (CK), as well as cumulative CK. In addition, the time until reperfusion was considerably less than for the control group (p=0.014). Long-term data showed significant differences in reinfarction (p=0.015), as well as in major adverse cardiovascular events, between the 2 groups (p<0.0001).

CONCLUSION

These data, because of the wide interval between collection and current analysis, could have inherited historical bias. Nonetheless, they are also uniquely indicating the potential of CSI to induce not only immediate, but also clinically significant long-term, effects as an adjunct to reperfusion therapy. Therefore, CSI should be, once again, on the study agenda and be placed under contemporary and best-available scientific scrutiny.

p38-MAPK is involved in restoration of the lost protection of preconditioning by nicorandil in vivo

Nicorandil, a selective mitochondrial K(ATP) channel opener, reinstates the waned protection after multiple cycles of preconditioning. In this study, we determined the signal transduction activated in heart after 3 or 8 cycles of preconditioning and prolonged ischemia in rabbits treated with placebo or nicorandil. In a first series (eight groups) we evaluated the (%) infarct to risk ratio after 30 min ischemia/3 h reperfusion and in a second series (six groups), we assessed the intracellular levels of cyclic GMP (c-GMP), protein kinase C (PKC) activity and p38-mitogen activated protein kinase (p38-MAPK) phosphorylation from heart samples taken during the long ischemia. Cardioprotection by 3 cycles of preconditioning (11.7+/-3.8% vs 45.9+/-5.2% in the control, P<0.001) was lost after 8 cycles (43.9+/-5.1%, P=NS vs control). Nicorandil restored it to the levels of classic preconditioning (13.7+/-2.4% vs 40.8+/-3.5% in respective controls, P<0.001). This was reversed by the p38-MAPK inhibitor SB203580 (48.8+/-5.1%) which had no protective effect in the control group (44.6+/-5.8%). In the placebo-treated rabbits, intracellular c-GMP and PKC were increased only in the group subjected to 3 cycles of preconditioning. Despite that nicorandil equalizes the intracellular levels of c-GMP, PKC and activated p38-MAPK at the long ischemia, specific alterations of p38-MAPK phosphorylation differentiate the protected groups. Our data delineate the signal transduction mechanism mediating the beneficial effect of nicorandil and imply that the recapture of the lost protection is due to a dynamic process of the intracellular mediators accompanied by an increase in p38-MAPK phosphorylation and not to an instantaneous event.