Chronotropic effects of cilostazol, a new antithrombotic agent, in patients with bradyarrhythmias

The Atrial Fibrillation and Heart Failure with Preserved Ejection Fraction "Twindemic" - Shared Root Causes and Treatment Targets

Heart failure with preserved ejection fraction (HFpEF) and atrial fibrillation (AF) are comorbid conditions that are increasingly prevalent and have a high socioeconomic burden. This article discusses their shared pathophysiology, focusing on the triad of hypertension, obesity, and aging. We highlight the misperception that pharmacologic heart rate lowering is beneficial, which has resulted in an overprescription of beta-blockers in HFpEF and AF. In contrast, heart rate modulation through accelerated pacing provides hemodynamic and structural advantages, which have yielded significant improvements in quality of life, physical activity, and AF burden in the myPACE trial of patients with preclinical or overt HFpEF.

Efficacy and safety of cilostazol-based triple antiplatelet therapy compared with clopidogrel-based dual antiplatelet therapy in patients with acute ST-elevation myocardial infarction undergoing percutaneous coronary intervention: A multicenter, randomized, open-label, phase 4 trial

BACKGROUND

Previous studies reported that compared to conventional dual antiplatelet therapy (DAT; aspirin + clopidogrel), triple antiplatelet therapy (TAT), involving the addition of cilostazol to DAT, had better clinical outcomes in patients with ST-elevation myocardial infarction (STEMI). However, the optimal duration of TAT is yet to be determined.

METHODS

In total, 985 patients with STEMI who underwent primary percutaneous coronary intervention (PCI) with drug-eluting stents (DESs) were prospectively enrolled in 15 PCI centers in South Korea and China. We randomly assigned patients into 3 groups: DAT (aspirin and clopidogrel for 12 months), TAT 1M (aspirin, clopidogrel, and cilostazol for 1 month), and TAT 6M (aspirin, clopidogrel, and cilostazol for 6 months). The primary endpoint was 1-year major adverse cardiovascular events (MACEs), defined as a composite of all-cause death, recurrent myocardial infarction, stroke, or repeat revascularization.

RESULTS

The primary endpoint did not differ among the 3 groups (8.8% in DAT, 11.0% in TAT 1M, and 11.6% in TAT 6M; hazard ratio for TAT 1M vs DAT, 1.302; 95% confidence interval [CI], 0.792-2.141; P = .297; hazard ratio for TAT 6M vs DAT, 1.358; 95% CI, 0.829-2.225; P = .225). With respect to in-hospital outcomes, more bleeding events occurred in the TAT group than in the DAT group (1.3% vs 4.7% vs 2.6%, P = .029), with no significant differences in major bleeding events. Additionally, the TAT group had a higher incidence of headaches (0% vs 1.6% vs 2.6%, P = .020).

CONCLUSIONS

The addition of cilostazol to DAT did not reduce the incidence of 1-year MACEs compared with DAT alone. Instead, it may be associated with an increased risk of drug intolerance and side effects, including in-hospital bleeding and headaches.

Efficacy of cilostazol in canine bradyarrhythmia

Recently, cilostazol, a phosphodiesterase III inhibitor, has been described as alternative medical treatment for canine bradyarrhythmia in cases for which pacemaker implantation was not indicated or available. In this retrospective study, we investigated the use and efficacy of cilostazol in dogs with bradyarrhythmia in Japan. Dogs that had been brought to the Tokyo University of Agriculture and Technology Animal Medical Center and 23 veterinary hospitals in Japan and been treated with cilostazol initially as the only therapeutic strategy for bradyarrhythmia between January 2010 and August 2021 were included in this study. Survival analyses were performed using Cox proportional hazards analysis, the log-rank test, and the generalized Wilcoxon test to evaluate the efficacy of cilostazol. Fifty-nine privately owned dogs were included in this study. In the survival time analysis, the risk of death was significantly lower and the survival rate was higher in cases in which cilostazol was administered at 10 mg/kg or more per dose. A third-degree atrioventricular block also significantly increased the risk of death and was associated with a lower survival rate. However, in some patients with a third-degree atrioventricular block, there was an increase in the ventricular rate and improvement in clinical symptoms without disappearance or decrease of the atrioventricular block. This study had several important findings that have not previously been reported concerning the use of cilostazol for canine bradyarrhythmia, including the appropriate dose in a clinical setting and the efficacy and prognosis according to the type of bradyarrhythmia.

Incidence of non-benign arrhythmia in neonatal intensive care unit: 18 years experience from a single center

Background

Non-benign arrhythmias, which require urgent recognition and care in neonatal intensive care unit (NICU) settings, are rare but can severely impact neonates. We aimed to clarify the epidemiology and characteristics of non-benign arrhythmias and their influence on neonates.

Methods

This single-center retrospective study included patients admitted to the NICU at Kurashiki Central Hospital between January 2001 and December 2019. Only patients with structurally normal hearts were included. The use of direct cardioversion (DC), antiarrhythmic agents, and the presence of risk factors was reviewed from medical records.

Results

Of the 8082 admissions, 2919 patients (36.1%) were low birth weight infants (LBWI) weighing less than 1500 g. There were 23 patients with arrhythmias (nine of them were LBWIs) with an incidence of 0.28%. There were 16 patients with tachyarrhythmia (eight supraventricular tachycardia [SVT] cases, three atrial flutters [AFL] cases, three ventricular tachycardia cases, two junctional ectopic tachycardia cases), and seven with bradyarrhythmia (all with complete atrioventricular [AV] block). For tachyarrhythmia cases, seven patients required DC, and eight were on antiarrhythmic agents at the time of discharge. Two patients (28.5%) with complete AV block required pacemaker implantation before discharge. The treatment strategy was dependent on the type of arrhythmia. All patients were discharged without significant morbidities.

Conclusions

The incidence of non-benign arrhythmias was as low as 0.28%. Arrhythmias can be managed successfully in neonates, yet risk factors related to mortality warrant further study.

Update on Cilostazol: A Critical Review of Its Antithrombotic and Cardiovascular Actions and Its Clinical Applications

Cilostazol, a phosphodiesterase III inhibitor, has vasodilating and antiplatelet properties with a low rate of bleeding complications. It has been used over the past 25 years for improving intermittent claudication in patients with peripheral artery disease (PAD). Cilostazol also has demonstrated efficacy in patients undergoing percutaneous revascularization procedures for both PAD and coronary artery disease. In addition to its antithrombotic and vasodilating actions, cilostazol also inhibits vascular smooth muscle cell proliferation via phosphodiesterase III inhibition, thus mitigating restenosis. Accumulated evidence has shown that cilostazol, due to its "pleiotropic" effects, is a useful, albeit underutilized, agent for both coronary artery disease and PAD. It is also potentially useful after ischemic stroke and is an alternative in those who are allergic or intolerant to classical antithrombotic agents (eg, aspirin or clopidogrel). These issues are herein reviewed together with the pharmacology and pharmacodynamics of cilostazol. Large studies and meta-analyses are presented and evaluated. Current guidelines are also discussed, and the spectrum of cilostazol's actions and therapeutic applications are illustrated.

Pharmacologic Approach to Sinoatrial Node Dysfunction

The spontaneous activity of the sinoatrial node initiates the heartbeat. Sino-atrial node dysfunction (SND) and sick sinoatrial (sick sinus) syndrome are caused by the heart's inability to generate a normal sinoatrial node action potential. In clinical practice, SND is generally considered an age-related pathology, secondary to degenerative fibrosis of the heart pacemaker tissue. However, other forms of SND exist, including idiopathic primary SND, which is genetic, and forms that are secondary to cardiovascular or systemic disease. The incidence of SND in the general population is expected to increase over the next half century, boosting the need to implant electronic pacemakers. During the last two decades, our knowledge of sino-atrial node physiology and of the pathophysiological mechanisms underlying SND has advanced considerably. This review summarizes the current knowledge about SND mechanisms and discusses the possibility of introducing new pharmacologic therapies for treating SND.

Cilostazol uncovers covert atrial fibrillation in non-cardioembolic stroke

BACKGROUND

We hypothesized that administration of cilostazol may clarify the occult atrial fibrillation (AF) during hospitalization in mild stroke patients, who has no history of AF.

METHODS

From our prospective non-cardioembolic stroke study, randomized to dual antiplatelet therapy using cilostazol and aspirin or aspirin alone trial (ADS), data on the presence or absence of AF were retrospectively analyzed. In the ADS, during hospitalization, as a routine examination, presence of AF was investigated using electrocardiogram (ECG), ECG monitoring and Holter ECG. Multivariate regression analysis was conducted to evaluate the independent parameters related to the AF. Clinical outcome at 3 months was evaluated using modified Rankin Scale (mRS) score.

RESULTS

Data on 1194 patients (793 [66%] men; median age [interquartile range] of 69 [61-77] years, National Institutes of Health Stroke Scale score 2 [1-4], onset-to-admission 10.8 [4.7-20.5] hours) were retrospectively analyzed. AF was newly detected in 41 (3%) patients (3 by ECG, 21 by the ECG monitoring and 17 by the Holter ECG) during hospitalization. Patients treated with combined cilostazol and aspirin therapy frequently had the AF than those took aspirin alone (5% vs. 2%, p = .007). Multivariate regression analysis showed that cilostazol administration was one of the independent factors for new-AF (odds ratio 2.672, 95%CI: 1.205-5.927, p = .016). The frequency of mRS 0-1 was 68% in the new-AF group and 67% in the non-AF group (p = 1.000).

CONCLUSION

Cilostazol therapy may increase the detectability of AF in acute non-cardioembolic stroke, though the new-AF was not related to clinical outcome at 3 months.

Long-term management of high-grade atrioventricular block using cilostazol in a cat

Case summary

A 12-year-old neutered female domestic shorthair cat was admitted for syncope. Clinical signs and electrocardiography revealed high-grade atrioventricular (AV) block. Treatment with cilostazol ameliorated the clinical signs and arrhythmia. However, the high-grade AV block recurred on several occasions. After 640 days, the cat presented again with clinical deterioration owing to reoccurrence of the arrhythmia and it died 11 days later. Histopathological examination revealed a loss of conduction cells within the His bundle.

Relevance and novel information

To our knowledge, this is the first report of high-grade AV block treated with cilostazol in a cat. Treatment with cilostazol prolonged survival for 650 days without pacemaker implantation. Histological findings suggested that the AV block was related to fibrosis of the impulse conduction system.

Efficacy of cilostazol for sick sinus syndrome to avoid permanent pacemaker implantation: A retrospective case-control study

BACKGROUND

Currently, bradycardia treatment is limited to permanent pacemaker (PM) implantation. No consensus exists as to its optimal medication regimen. However, as cilostazol accelerates heart rate (HR) in bradycardia, we investigated its efficacy for sick sinus syndrome (SSS) to avoid permanent PM implantation.

METHODS

This was a retrospective, case-control study. We included 192 consecutive patients diagnosed with SSS (after applying some exclusion criteria), of whom 54 received cilostazol (cilostazol group) and 138 did not receive cilostazol (control group). The primary endpoint was the PM implantation rate after 6 months; secondary endpoints were 1- and 3-month PM implantation rates, HR after 1 week, 1 and 6 months, and cilostazol side effects.

RESULTS

The 6-month PM implantation rate was lower in the cilostazol than the control group (20.4% vs. 55.8%, respectively; p<0.001). In multivariate analysis, cilostazol decreased the 6-month PM implantation rate (OR: 0.22; 95% CI: 0.08-0.55; p=0.001). Although baseline HR was significantly lower in the cilostazol group, HR in this group increased and did not significantly differ between the two groups after 1 week, 1 and 6 months. In subgroup analyses of symptomatic patients, the PM implantation rates after 6 months were significantly lower in the cilostazol group than in the control group.

CONCLUSIONS

Cilostazol was effective for symptomatic SSS to avoid PM implantation by increasing HR.

Risk of Heart Failure Hospitalization Associated With Cilostazol in Diabetes: A Nationwide Case-Crossover Study

Background and Objective: It has been suggested to avoid cilostazol, the first-line therapy for peripheral arterial disease, in patients with congestive heart failure (HF). The objective of this study was to evaluate the risk of hospitalization for heart failure (HHF) associated with cilostazol use in the patients of diabetes mellitus. Methods: This case-crossover study retrieved records on diabetic patients > 20 years of age who were hospitalized for heart failure during the period of 2009-2011 from the Taiwan National Health Insurance Database. The "current" period was defined as 1-30 days prior to HHF whereas the 91-120 days prior to HHF served as the "reference" period. The exposure status just preceding the event is compared with exposure of the same person in one or more referent remote to the event. Adjusted odds ratios (OR) were used to estimate time-varying discordant exposure by the ratio of the number exposed to cilostazol only during the case period to the number exposed to cilostazol only during the control period. Results: A total of 47,506 diabetic patients were included in the analysis (average age: 72.7 ± 12.4, percentage of males: 48%). A total of 399 patients (0.84%) received cilostazol only in the current period, and 252 (0.53%) received cilostazol only in the reference period. After adjustment for other medications, a significant association was found between cilostazol and HHF (OR: 1.35, 95% CI: 1.14-1.59). After further adjustment for time-varying co-morbidities the ORs remained essentially the same. Sensitivity analyses using different definitions of control period (ranging from 31-60, 61-90, to 121-150 days before index date) yielded adjusted ORs of 1.43 (95% CI: 1.14-1.79), 1.31 (95% CI: 1.09-1.57) and 1.23 (95% CI: 1.06-1.44), respectively suggesting the robustness of our study findings. Conclusion: Use of cilostazol may be positively related to the risk of HHF. Further studies are warranted to explore the underlying mechanisms and to confirm the association.

Complex regional pain syndrome induced by pacemaker implantation for sick sinus syndrome

A 53-year-old woman reported burning pain, muscle weakness, and dysesthesia of the left arm 2 months after permanent pacemaker insertion in the ipsilateral side for the treatment of sick sinus syndrome. Complex regional pain syndrome (CRPS) induced by pacemaker implantation was diagnosed. In 2017, her pulse generator became exhausted and was exchanged carefully to avoid exacerbation of CRPS, under the application of local anesthesia and premedication. Six months later, the patient's grip strength in her left hand remained lower relative to that in her right hand. Although rare, the presence of CRPS following device implantation should be remembered.

Long term effects of cilostazol in a dog with sick sinus syndrome

Sick sinus syndrome (SSS) is a type of bradyarrhythmia that can lead to syncope. Cilostazol has been reported to be an effective treatment for human patients with SSS and other bradyarrhythmias. This report describes the successful long-term treatment with cilostazol in a dog with SSS. A nine-year old intact male Miniature Schnauzer presented with a history of syncopal episodes and unsteady gait. After cilostazol treatment, the total heart rate (HR), mean HR, and frequency of premature ventricular contractions (PVCs) increased, while the maximum HR and maximum pause time decreased. Additionally, the number of syncopal episodes decreased. The dog died suddenly, 1,418 days after the start of cilostazol treatment. Cilostazol may be a useful therapeutic agent in canines with SSS.

Cellular and ionic mechanisms underlying the effects of cilostazol, milrinone, and isoproterenol to suppress arrhythmogenesis in an experimental model of early repolarization syndrome

BACKGROUND

Early repolarization syndrome (ERS) is associated with polymorphic ventricular tachycardia (PVT) and ventricular fibrillation, leading to sudden cardiac death.

OBJECTIVE

The present study tests the hypothesis that the transient outward potassium current (Ito)-blocking effect of phosphodiesterase-3 (PDE-3) inhibitors plays a role in reversing repolarization heterogeneities responsible for arrhythmogenesis in experimental models of ERS.

METHODS

Transmembrane action potentials (APs) were simultaneously recorded from epicardial and endocardial regions of coronary-perfused canine left ventricular (LV) wedge preparations, together with a transmural pseudo-electrocardiogram. The Ito agonist NS5806 (7-15 μM) and L-type calcium current (ICa) blocker verapamil (2-3 μM) were used to induce an early repolarization pattern and PVT.

RESULTS

After stable induction of arrhythmogenesis, the PDE-3 inhibitors cilostazol and milrinone or isoproterenol were added to the coronary perfusate. All were effective in restoring the AP dome in the LV epicardium, thus abolishing the repolarization defects responsible for phase 2 reentry and PVT. Arrhythmic activity was suppressed in 7 of 8 preparations by cilostazol (10 μM), 6 of 7 by milrinone (2.5 μM), and 7 of 8 by isoproterenol (0.1-1 μM). Using voltage clamp techniques applied to LV epicardial myocytes, both cilostazol (10 μM) and milrinone (2.5 μM) were found to reduce Ito by 44.4% and 40.4%, respectively, in addition to their known effects to augment ICa.

CONCLUSION

Our findings suggest that PDE-3 inhibitors exert an ameliorative effect in the setting of ERS by producing an inward shift in the balance of current during the early phases of the epicardial AP via inhibition of Ito as well as augmentation of ICa, thus reversing the repolarization defects underlying the development of phase 2 reentry and ventricular tachycardia/ventricular fibrillation.

J-wave syndromes: Brugada and early repolarization syndromes

A prominent J wave is encountered in a number of life-threatening cardiac arrhythmia syndromes, including the Brugada syndrome and early repolarization syndromes. Brugada syndrome and early repolarization syndromes differ with respect to the magnitude and lead location of abnormal J waves and are thought to represent a continuous spectrum of phenotypic expression termed J-wave syndromes. Despite two decades of intensive research, risk stratification and the approach to therapy of these 2 inherited cardiac arrhythmia syndromes are still undergoing rapid evolution. Our objective in this review is to provide an integrated synopsis of the clinical characteristics, risk stratifiers, and molecular, ionic, cellular, and genetic mechanisms underlying these 2 fascinating syndromes that have captured the interest and attention of the cardiology community in recent years.

Cilostazol ameliorates atrial ionic remodeling in long-term rapid atrial pacing dogs

Objective:

Ionic remodeling has a close correlation with the occurrence of atrial fibrillation (AF). Atrial tachypacing remodeling is associated with characteristic ionic remodeling. The purpose of this study was to assess the efficacy of cilostazol, an oral phosphodiesterase 3 inhibitor, for preventing atrial ionic remodeling in long-term rapid atrial pacing (RAP) dogs.

Methods:

We use the methods of patch-clamp and molecular biology to investigate the effect of cilostazol on ion channel and channel gene expression in long-term RAP dogs. Twenty-one dogs were randomly assigned to sham, control paced, and paced+cilostazol (5 mg/kg/d, cilo) groups, with 7 dogs in each group. The sham group was instrumented with a pacemaker but without pacing. RAP at 500 beats/min was maintained for 2 weeks in the paced and cilo groups. During the pacing, cilostazol was given orally in the cilo group. Whole-cell patch-clamp technique was used to record atrial L-type Ca²+ (I_CaL) and fast sodium channel (I_Na) ionic currents. Western blot and RT-PCR were applied to estimate the gene expression of the I_CaLa) 1C (Cav1.2) and I_Nav1.5a) Nav1.5a) subunits. Statistical analysis was performed using SPSS 13.0.

Results:

The density of I_CaL and I_Na currents (pA/pF) was significantly reduced in the paced group (I_CaL: -6.55±1.42 vs. -4.46±0.59 pA/pF; I_Na: -48.24±10.54 vs. -30.48±5.20 pA/pF, p<0.01). The paced+cilo group could not increase the density of I_CaL currents (I_CaL: -4.37±1.25 pA/pF, p>0.05], while the I_Na currents were recovered (-44.54±12.65 pA/pF, p<0.01) compared with the paced group. The mRNA and protein expression levels of Cav1.2 and Nav1.5a were apparently down-regulated in the paced group (p<0.01), but after cilostazol treatment, both of these subunits were up-regulated significantly (p<0.01).

Conclusion:

Cilostazol may have protective effects on RAP-induced atrial ionic remodeling.

Phosphodiesterase-3 inhibitor (cilostazol) attenuates oxidative stress-induced mitochondrial dysfunction in the heart

Background

Cilostazol is a type 3 phosphodiesterase inhibitor which has been previously demonstrated to prevent the occurrence of tachyarrhythmia and improve defibrillation efficacy. However, the mechanism for this beneficial effect is still unclear. Since cardiac mitochondria have been shown to play a crucial role in fatal cardiac arrhythmias and that oxidative stress is one of the main contributors to arrhythmia generation, we tested the effects of cilostazol on cardiac mitochondria under severe oxidative stress.

Methods

Mitochondria were isolated from rat hearts and treated with H₂O₂ to induce oxidative stress. Cilostazol, at various concentrations, was used to study its protective effects. Pharmacological interventions, including a mitochondrial permeability transition pore (mPTP) blocker, cyclosporine A (CsA), and an inner membrane anion channel (IMAC) blocker, 4′-chlorodiazepam (CDP), were used to investigate the mechanistic role of cilostazol on cardiac mitochondria. Cardiac mitochondrial reactive oxygen species (ROS) production, mitochondrial membrane potential change and mitochondrial swelling were determined as indicators of cardiac mitochondrial function.

Results

Cilostazol preserved cardiac mitochondrial function when exposed to oxidative stress by preventing mitochondrial depolarization, mitochondrial swelling, and decreasing ROS production.

Conclusions

Our findings suggest that cardioprotective effects of cilostazol reported previously could be due to its prevention of cardiac mitochondrial dysfunction caused by severe oxidative stress.

The blood glucose level increased in parallel with the heart rate following cilostazol administration in three diabetic patients

Cilostazol, a phosphodiesterase III inhibitor, is known to increase the heart rate; however, its effects on glucose metabolism remain unclear. We observed that the blood glucose level varied in parallel with the heart rate immediately after starting or stopping cilostazol therapy in three patients with type 2 diabetes. This finding indicates that cilostazol induces hyperglycemia and tachycardia in a portion of diabetic patients, presumably via similar pharmacological effects on different organs. Much more attention should be paid to the possible effects of cilostazol on glycemic control, including taking into consideration the risk-benefit ratio of cilostazol use and individual circumstances.

Cilostazol decreases total atrial conduction time in patients with peripheral artery disease

Objective:

Total atrial conduction time (TACT) is the most important parameter in predicting the development of new-onset atrial fibrillation. We investigated the effect of cilostazol therapy on TACT in patients with peripheral artery disease.

Methods:

Thirty patients with peripheral artery disease were treated with cilostazol (200 mg/day) for 6 months. The baseline echocardiographic total atrial conduction time parameter was compared with the 6-month follow-up.

Results:

The TACT duration was decreased in all patients compared with the baseline after therapy (121.8 ± 19.3 vs. 109.1 ± 15.9 milliseconds, p<0.001). However, left atrial (LA) diameter was not changed with the therapy. The reduction of TACT duration was correlated with the increase in mitral E wave velocity/mitral A wave velocity ratio (r=-0.48, p<0.003).

Conclusion:

Our results showed that 200 mg cilostazol treatment decreased TACT duration in patients with peripheral artery disease, which may also prevent the development and/or recurrence of atrial fibrillation (AF).

Cellular mechanisms underlying the effects of milrinone and cilostazol to suppress arrhythmogenesis associated with Brugada syndrome

BACKGROUND

Brugada syndrome is an inherited disease associated with vulnerability to ventricular tachycardia and sudden cardiac death in young adults. Milrinone and cilostazol, oral phosphodiesterase (PDE) type III inhibitors, have been shown to increase L-type calcium channel current (ICa) and modestly increase heart rate by elevating the level of intracellular cyclic adenosine monophosphate.

OBJECTIVE

To examine the effectiveness of these PDE inhibitors to suppress arrhythmogenesis in an experimental model of Brugada syndrome.

METHODS

Action potential (AP) and electrocardiographic recordings were obtained from epicardial and endocardial sites of coronary-perfused canine right ventricular wedge preparations. The Ito agonist NS5806 (5 μM) and Ca(2+) channel blocker verapamil (2 μM) were used to pharmacologically mimic Brugada phenotype.

RESULTS

The combination induced all-or-none repolarization at some epicardial sites but not others, leading to ST-segment elevation as well as an increase in both epicardial and transmural dispersion of repolarization. Under these conditions, phase 2 reentry developed as the epicardial AP dome propagated from sites where it was maintained to sites at which it was lost, generating closely coupled extrasystoles and ventricular tachycardia. The addition of the PDE inhibitor milrinone (2.5 μM) or cilostazol (5-10 μM) to the coronary perfusate restored the epicardial AP dome, reduced dispersion, and abolished phase 2 reentry-induced extrasystoles and ventricular tachycardia.

CONCLUSIONS

Our study identifies milrinone as a more potent alternative to cilostazol for reversing the repolarization defects responsible for the electrocardiographic and arrhythmic manifestations of Brugada syndrome. Both drugs normalize ST-segment elevation and suppress arrhythmogenesis in experimental models of Brugada syndrome.

Effects of cilostazol in the heart

Cilostazol is a selective phosphodiesterase 3 (PDE3) inhibitor approved by the Food and Drug Administration for treatment of intermittent claudication. It has also been used in bradyarrhythmic patients to increase heart rates. Recently, cilostazol has been shown to prevent ventricular fibrillation in patients with Brugada syndrome. Cilostazol is hypothesized to suppress transient outward potassium (Ito) current and increase inward calcium current, thus, maintaining the dome (phase 2) of action potential, decreasing transmural dispersion of repolarization and preventing ventricular fibrillation. Although many PDE3 inhibitors have been shown to increase cardiac arrhythmia in heart failure, cilostazol has presented effects that are different from other PDE3 inhibitors, especially adenosine uptake inhibition. Owing to this effect, cilostazol could be an effective cardioprotective drug, with its beneficial effects in preventing arrhythmia. In this review, the cardiac electrophysiological effects of cilostazol are presented and its possible cardioprotective effects, particularly in preventing ventricular fibrillation, are discussed, with emphasis on the need to further verify its clinical benefits.

Recovery of advanced atrioventricular block by cilostazol

We describe a case of advanced atrioventricular (AV) block, in which treatment with cilostazol was effective in recovering the AV conduction. The patient was referred to our hospital for close examination of the advanced AV block and permanent pacemaker implantation. Although the patient had experienced third-degree AV block with occasional AV synchrony for more than two days, the AV conduction completely recovered after treatment with oral cilostazol at 200 mg/day. Here we discuss the possible mechanism of the improvement in the AV conduction by cilostazol.

Cilostazol attenuates ventricular arrhythmia induction and improves defibrillation efficacy in swine

Previous reports demonstrated that cilostazol, a phosphodiesterase 3 inhibitor, affected cellular electrophysiology and reduced episodes of ventricular fibrillation (VF) in patients with Brugada syndrome. However, its effects on VF induction and defibrillation efficacy have never been investigated. We tested the hypothesis that cilostazol increases the VF threshold (VFT) and decreases the upper limit of vulnerability (ULV) and the defibrillation threshold (DFT). A total of 48 pigs were randomly assigned to defibrillation and VF induction studies. The diastolic pacing threshold (DPT), VFT, ULV, DFT, and effective refractory period were determined before and after the infusion of cilostazol at 6 mg/kg, 3 mg/kg, or vehicle. The DPT was significantly increased after administration of 3 and 6 mg/kg cilostazol. The ULV and DFT were significantly decreased after administration of 6 mg/kg cilostazol only. The ULV in the 6 mg/kg group had 12% lower peak voltage and 25% lower total energy, and the DFT had 13% lower peak voltage and 25% lower total energy. The VFT was not altered in any experimental group. This study shows that cilostazol administration significantly increased the DPT, which was associated with significantly reduced DFT and ULV.

Hemorrhagic cholecystitis in an elderly patient taking aspirin and cilostazol

Hemorrhage is a rare complication of acute cholecystitis. Patients who develop this complication often are receiving anticoagulation therapy or have a pathologic coagulopathy. We present a case of an elderly patient who developed hemorrhagic cholecystitis while taking aspirin and cilostazol, a phosphodiesterase inhibitor. The patient underwent an emergent abdominal exploration. A large, blood-filled gallbladder was found along with a large hematoma between the liver and gallbladder. We also briefly review the literature regarding hemorrhagic cholecystitis, hemorrhage into the biliary tree, and hemorrhage as a complication of aspirin and phosphodiesterase inhibitor therapy.

Impact of chronotropic effect of cilostazol after acute myocardial infarction: insights from change in left ventricular volume and function

BACKGROUND

Cilostazol, a phosphodiesterase inhibitor, is an antiplatelet agent with positive chronotropic effect, the impact of which on left ventricular (LV) volume and function in acute myocardial infarction (AMI) was evaluated in the present study.

METHODS AND RESULTS

In 56 patients with AMI treated with primary coronary stenting, serial echocardiographic studies within 24 h and at 6 months were performed. Patients received a conventional antiplatelet regimen either without cilostazol (group 1, n=29) or with cilostazol (group 2, n=27). At 6 months, the difference in the change in heart rate between group 1 and group 2 was statistically significant (9.9 beats/min; p=0.04). However, changes in LV end-systolic volume (LVESV) (7.1+/-8.2 vs 10.0+/-21.7 ml, p=0.60), LV ejection fraction (EF) (8.2+/-9.9 vs 9.0+/-12.6%, p=0.85) and the ratio of early mitral inflow velocity to the mitral annular velocity (E/E') (0.6+/-3.7 vs -1.7+/-3.2) were not different between the 2 groups. Cardiac event rate was similar between the 2 groups. On multivariate regression analyses, cilostazol therapy had no significant influence on the changes in LVESV, LVEF or E/E'.

CONCLUSIONS

In this study, the addition of cilostazol on conventional drug therapy had no adverse influence on LV remodeling or LV function after AMI.

Congenital atrial standstill associated with coinheritance of a novel SCN5A mutation and connexin 40 polymorphisms

BACKGROUND

Congenital atrial standstill has been linked to SCN5A. Incomplete penetrance observed in atrial standstill has been attributed in part to the digenic inheritance of polymorphisms in the atrial-specific gap junction connexin 40 (Cx40) in conjunction with an SCN5A mutation.

OBJECTIVES

The purpose of this study was to determine the clinical and biophysical characteristics of a novel SCN5A mutation identified in a family with atrial standstill.

METHODS

Family members of an apparently sporadic case of atrial standstill underwent genetic screening of SCN5A and atrial-specific genes including Cx40. Biophysical properties of the wild-type (WT) and mutant SCN5A channels in a heterologous expression system were studied using the whole-cell patch clamp technique.

RESULTS

The novel SCN5A mutation L212P was identified in the proband (age 11 years) and his father. The father was in normal sinus rhythm. The proband had no P waves on surface ECG, and his right atrium could not be captured by pacing. The recombinant L212P Na channel showed a large hyperpolarizing shift in both the voltage dependence of activation (WT: -48.1 +/- 0.9 mV; L212P: -63.5 +/- 1.5 mV; P < .001) and inactivation (WT: -86.6 +/- 0.9 mV; L212P: -95.6 +/- 0.8 mV; P < .001) and delayed recovery from inactivation. Further screenings for genetic variations that might mitigate L212P dysfunction revealed that the proband, but not his father, carries Cx40 polymorphisms inherited from his asymptomatic mother.

CONCLUSION

These results suggest that genetic defects in SCN5A most likely underlie atrial standstill. Coinheritance of Cx40 polymorphisms is a possible genetic factor that modifies the clinical manifestation of this inherited arrhythmia.

Chronotropic Effect of the Antithrombotic Agent Cilostazol in a Patient with Sick Sinus Syndrome and Syncope

In this case report we describe an 80-year-old man with sick sinus syndrome (SSS) who developed syncope attacks. The diagnosis of SSS was based on electrocardiographic evidence of markedly prolonged sinus arrests associated with syncope attacks while in hospital. The patient was given cilostazol, an anti-thrombotic agent that selectively inhibits cyclic nucleotide phosphodiesterase type 3, at a dose of 100 mg twice daily. The syncope attacks ceased, and an electrocardiogram obtained 1 week after the start of cilostazol administration showed no evidence of sinus arrest. The outcome of this case suggests that cilostazol may be useful in patients with syncope attacks due to SSS, although the long-term chronotropic effects of cilostazol need to be evaluated.

Effect of cilostazol on the ventricular escape rate and neurohumoral factors in patients with third-degree atrioventricular block

STUDY OBJECTIVES

This study assessed whether the antiplatelet agent cilostazol, which has potent cyclic nucleotide phosphodiesterase type-3 inhibitory activity, affects the ventricular escape rate and neurohumoral factors in patients with third-degree atrioventricular block.

DESIGN

Prospective, but nonrandomized, study.

SETTING

Cardiology division of an acute care hospital.

PATIENTS

We studied 12 patients with third-degree intra-His or infra-His atrioventricular block who were in functional class II or III of the New York Heart Association classification. None of the patients had experienced Adams-Stokes attacks.

INTERVENTIONS

These patients were given cilostazol orally at a dose of 200 mg daily for at least 1 week.

MEASUREMENTS AND RESULTS

Before and after treatment with cilostazol, continuous 24-h ECG monitoring and measurement of plasma natriuretic peptide concentrations were performed. Cilostazol significantly increased the mean (+/- SEM) total 24-h QRS count from 57,300 +/- 2,800 to 74,400 +/- 3,200 beats (p = 0.001) and significantly decreased the maximum geometric mean R-R interval over a 24-h period from 1,900 ms (95% confidence interval [CI], 1,700 to 2,100 ms) to 1,600 ms (95% CI, 1,400 to 1,900 ms; p = 0.02), although none of the patients showed the abolishment of the atrioventricular conduction abnormalities. The total 24-h count of premature ventricular beats was not different before treatment (15 beats; 95% CI, 5 to 44 beats) and after treatment (12 beats; 95% CI, 5 to 30 beats; p = 0.57). Treatment with cilostazol significantly decreased the concentration of plasma atrial natriuretic peptide from 88 pg/mL (95% CI, 49 to 160 pg/mL) to 51 pg/mL (95% CI, 32 to 80 pg/mL; p = 0.007) and of brain natriuretic peptide from 166 pg/mL (95% CI, 71 to 389 pg/mL) to 77 pg/mL (95% CI, 30 to 178 pg/mL; p = 0.02).

CONCLUSIONS

Cilostazol significantly increased the ventricular escape rate and significantly decreased the level of circulating natriuretic peptides. Thus, cilostazol could be safely given to selected patients over the short term with third-degree atrioventricular block.

Effects of a single oral dose of cilostazol on epicardial coronary arteries and hemodynamics in humans

Cilostazol, a novel cyclic adenosine monophosphate phosphodiesterase type III inhibitor, has been developed as an antiplatelet drug with a vasodilating action on peripheral arteries. The present study was designed to test, in humans, whether cilostazol can dilate the epicardial coronary arteries and what are its hemodynamic effects. Eight patients with chest pain syndrome were subjected to serial quantitative coronary arteriography immediately before and at 30, 60 and 150min after a single oral dose of cilostazol (200mg). Luminal cross-sectional areas (mm2) at the proximal and distal sites of major coronary arteries (6 segments at each sampling time) were significantly increased at 150 min after taking the drug. The percent increases relative to the baseline values were 25+/-7 (6.8+/-0.8-->8.3+/-1.0*) and 42+/-7% (2.1+/-0.3-->3.0+/-0.4*) in the right coronary artery, 24+/-5 (5.1+/-0.7-->6.1+/-0.8*) and 28+/-10% (1.6+/-0.31-->9+/-0.3*) in the left anterior descending artery, and 14+/-6 (5.9+/-0.9-->6.6+/-0.9*) and 24+/-10% (1.3+/-0.2-->1.5+/-0.2*) in the left circumflex artery, respectively (*p<0.05 vs baseline). This action, relative to that of nitroglycerine, was between 27% and 54%. Moreover, small but sustained decreases in systolic pulmonary pressure and stroke work index were observed. Thus, cilostazol has a mild coronary vasodilating action with minimal hemodynamic effects, thereby giving it a possible role in the treatment of coronary artery disease.

Inflammatory cytokines stimulate adrenomedullin expression through nitric oxide-dependent and -independent pathways

A body of evidence indicates that the production of adrenomedullin (ADM) in vivo is activated in states of inflammation. Our aim was to characterize the intracellular signaling pathways along which inflammation leads to a stimulation of ADM expression. For this purpose, we characterized the effects of inflammatory cytokines, tumor necrosis factor-alpha (100 microg/L), interleukin-1beta (20 microg/L), and interferon-gamma (0.5 U/L) on ADM gene expression in rat aortic vascular smooth muscle cells (AVSMCs). We found that inflammatory cytokines induced a time-dependent 12-fold upregulation of ADM mRNA in AVSMCs that was paralleled by a substantial increase in inducible NO synthase mRNA expression. The stimulatory effect of cytokines on ADM gene expression was attenuated by NO deprivation induced by Nomega-nitro-L-arginine methyl ester (1 mmol/L) and was in part mimicked by the NO donor S-nitroso-N-acetylpenicillamine (100 micromol/L). The cGMP analog 8-bromo-cGMP (100 micromol/L) had no effect on ADM gene expression, and inhibition of cGMP production by 1H-oxodiazolo-quinoxalin-1 (ODQ, 200 micromol/L) was not able to abrogate the increase of ADM mRNA induced by NO donation using S-nitroso-N-acetylpenicillamine (100 micromol/L). The significant induction of ADM gene expression by inflammatory cytokines and NO donation was also observed in mesangial cells, endothelial cells, and hepatocytes. These findings suggest that NO is a direct activator of ADM gene expression in a variety of cell types and that inflammatory cytokines stimulate ADM expression via both NO-dependent and -independent mechanisms. The stimulatory effect of NO appears to not be related to the classic guanylate cyclase-cGMP pathway.

Effects of cilostazol on heart rate and its variation in patients with atrial fibrillation associated with bradycardia

BACKGROUND

Heart-rate (HR) variability is an important predictor of mortality in patients with heart disease. We examined the effects of cilostazol, a quinolinone derivative, on HR and HR variability in patients with chronic atrial fibrillation associated with bradycardia episodes.

PATIENTS AND METHODS

Thirteen patients with chronic atrial fibrillation associated with bradycardia episodes (minimal HR <40/min and/or pauses, ie, episodes with an RR interval > 2.5 sec) received cilostazol (100 or 200 mg/day) orally for at least 2 months and 24-hour Holter electrocardiography was performed before and after the start of cilostazol administration.

RESULTS

Minimal HR was significantly increased, by an average of 14 beats/min (bpm), at 3.3 +/- 0.8 weeks (mean +/- SD) after the start of cilostazol treatment. The number of pauses was significantly decreased. As a consequence, mean HR was increased by an average of 18 bpm. Maximal HR was also increased by an average of 19 bpm. The circadian variation of the HR, determined by cosine fitting, was not changed by cilostazol treatment. The time-domain HR variabilities, ie, the SD of the mean RR interval and the SD of the 5-minute mean RR intervals, were also unchanged. New York Heart Association functional class was significantly improved and the plasma atrial natriuretic polypeptide level was significantly decreased after the initiation of cilostazol treatment.

CONCLUSION

Cilostazol improves the slow HR episodes associated with chronic atrial fibrillation and maintains the HR circadian variation and time-domain variability, indicating that cilostazol has therapeutic utility for the treatment of the slow HR associated with chronic atrial fibrillation.

Cilostazol

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