Intracoronary boluses of adenosine and sodium nitroprusside in combination reverses slow/no-reflow during angioplasty: a clinical scenario of ischemic preconditioning

Adenosine as adjunctive therapy in acute coronary syndrome: a meta-analysis of randomized controlled trials

AIMS

Adenosine has been tested in several randomized controlled trials (RCTs) to minimize the incidence of coronary microvascular obstruction (CMVO). The aim of this study was to pool all the RCTs comparing intracoronary or intravenous adenosine versus placebo in patients with acute coronary syndrome (ACS) undergoing myocardial revascularization.

METHODS AND RESULTS

PubMed and Scopus electronic databases were scanned for eligible studies up to 5th June 2022. A total of 26 RCTs with 5843 patients were included. Efficacy endpoints were major adverse cardiac events (MACE), all-cause death, non-fatal myocardial infarction, and heart failure. Atrioventricular blocks and ventricular fibrillation/sustained ventricular tachycardia (VF/SVT) were the safety endpoints. Myocardial blush grade, thrombolysis in myocardial infarction (TIMI) flow grade, left ventricular ejection fraction (LVEF), infarct size, and ST-segment resolution were also assessed. Adenosine administration was not associated with any clinical benefit in terms of MACE, all-cause death, non-fatal myocardial infarction, and heart failure. However, adenosine was associated with an increased rate of advanced atrioventricular blocks and of VF/SVT in studies with total mean ischaemic time >3 h, compared to placebo. Remarkably, among patients undergoing percutaneous coronary intervention, adenosine was associated with reduced myocardial blush grade 0-1 and TIMI flow grade 0-2, compared to placebo. Furthermore, adenosine did not show favourable effects on LVEF and infarct size.

CONCLUSION

Adenosine infusion, as adjunctive therapy in ACS, was associated with an increased risk of advanced atrioventricular blocks and increased rates of adenosine-triggered ventricular arrhythmias in patients with long ischaemic time, without providing any clinical benefit compared to placebo.

Adenosine-Induced Coronary Steal Is Observed in Patients Presenting With ST-Segment-Elevation Myocardial Infarction

Background Adenosine is used to treat no-reflow in the infarct-related artery (IRA) during ST-segment-elevation myocardial infarction intervention. However, the physiological effect of adenosine in the IRA is variable. Coronary steal-a reduction of blood flow to the distal coronary bed-can occur in response to adenosine and this is facilitated by collaterals. We investigated the effects of adenosine on coronary flow reserve (CFR) in patients presenting with ST-segment-elevation myocardial infarction to better understand the physiological mechanism underpinning the variable response to adenosine. Methods and Results Pressure-wire assessment of the IRA after percutaneous coronary intervention was performed in 93 patients presenting with ST-segment-elevation myocardial infarction to calculate index of microvascular resistance, CFR, and collateral flow index by pressure. Modified collateral Rentrop grade to the IRA was recorded, as was microvascular obstruction by cardiac magnetic resonance imaging. Coronary steal (CFR <0.9), no change in flow (CFR=0.9-1.1), and hyperemic flow (CFR >1.1) after adenosine occurred in 19 (20%), 15 (16%), and 59 (63%) patients, respectively. Patients with coronary steal had higher modified Rentrop score to the IRA (1 [0, 1.75] versus 0 [0, 1], P<0.001) and a higher collateral flow index by pressure (0.25±0.10 versus 0.15±0.10, P=0.004) than the hyperemic group. The coronary steal group also had significantly higher index of microvascular resistance (61.68 [28.13, 87.04] versus 23.93 [14.67, 37.00], P=0.006) and had more disease (stenosis >50%) in the donor arteries (52.63% versus 22.03%, P=0.02) than the hyperemic group. Conclusions Adenosine-induced coronary steal may be responsible for a reduction in coronary flow reserve in a proportion of patients presenting with ST-segment-elevation myocardial infarction. Registration URL: https://www.clinicaltrials.gov; Unique identifier: NCT03145194. URL: https://www.isrctn.com; Unique identifier: ISRCTN3176727.

Advances in Coronary No-Reflow Phenomenon-a Contemporary Review

PURPOSE OF REVIEW

Coronary artery no-reflow phenomenon is an incidental outcome of percutaneous coronary intervention in patients presenting with acute myocardial infarction. Despite advances in pharmacologic and non-pharmacologic therapies, coronary no-reflow phenomenon occurs more commonly than desired. It often results in poor clinical outcomes and remains as a relevant consideration in the cardiac catheterization laboratory. In this systematic review, we have sought to discuss the topic in detail, and to relay the most recent discoveries and data on management of this condition.

RECENT FINDINGS

We discuss several pharmacologic and non-pharmacologic treatments used in the prevention and management of coronary no-reflow and microvascular obstruction. Covered topics include the understanding of pharmacologic mechanisms of current and future agents, and recent discoveries that may result in the development of future treatment options. We conclude that the pathophysiology of coronary no-reflow phenomenon and microvascular obstruction still remains incompletely understood, although several plausible theories have led to the current standard of care for its management. We also conclude that coronary no-reflow phenomenon and microvascular obstruction must be recognized as a multifactorial condition that has certain predispositions and characteristics, therefore its prevention and treatment must begin pre-procedurally and be multi-faceted including certain medications and operator techniques in the cardiac catheterization laboratory.

Management of No-Reflow Phenomenon in the Catheterization Laboratory

At the conclusion of a primary percutaneous coronary intervention for ST-segment elevation myocardial infarction, and after the cardiologist makes certain that there is no residual stenosis following stenting, assessment of coronary flow becomes the top priority. The presence of no-reflow is a serious prognostic sign. No-reflow can result in poor healing of the infarct and adverse left ventricular remodeling, increasing the risk for major adverse cardiac events, including congestive heart failure and death. To achieve normal flow, features associated with a high incidence of no-reflow must be anticipated, and measures must be undertaken to prevent its occurrence. In this review, the authors discuss various preventive strategies for no-reflow as well as pharmacological and nonpharmacological interventions that improve coronary blood flow, such as intracoronary adenosine and nitroprusside. Nonpharmacological therapies, such as induced hypothermia, were successful in animal studies, but their effectiveness in reducing no-reflow in humans remains to be determined.

No reflow phenomenon in percutaneous coronary interventions in ST-segment elevation myocardial infarction

Percutaneous coronary intervention (PCI) is effective in opening the infarct related artery and restoring thrombolysis in myocardial infarction flow 3 (TIMI-flow 3) in large majority of ST-elevation myocardial infarction (STEMI). However there remain a small but significant proportion of patients, who continue to manifest diminished myocardial reperfusion despite successful opening of the obstructed epicardial artery. This phenomenon is called no-reflow. Clinically it manifests with recurrence of chest pain and dyspnea and may progress to cardiogenic shock, cardiac arrest, serious arrhythmias and acute heart failure. No reflow is regarded as independent predictor of death or recurrent myocardial infarction. No reflow is a multi-factorial phenomenon. However micro embolization of atherothrombotic debris during PCI remains the principal mechanism responsible for microvascular obstruction. This review summarizes the pathogenesis, diagnostic methods and the results of various recent randomized trials and studies on the prevention and management of no-reflow.

Tirofiban induces vasorelaxation of the coronary artery via an endothelium-dependent NO-cGMP signaling by activating the PI3K/Akt/eNOS pathway

Tirofiban, a glycoprotein IIb/IIIa inhibitor, is an antiplatelet drug extensively used in patients with acute coronary syndrome (ACS) and exerts an therapeutic effect on no-reflow phenomenon during percutaneous coronary intervention (PCI). Previous studies elucidated the vasodilation caused by tirofiban in the peripheral artery. However, whether tirofiban exerts a vasodilator effect on the coronary artery is unclear. Our present study found that tirofiban induced endothelium-dependent vasodilation in a concentration- and time-dependent manner in the isolated rat coronary artery pre-constricted by 5-hydroxytryptamine (5-HT). Further study showed that incubation of human umbilical venous endothelial cells (HUVECs) with tirofiban increased NO production, which was ascribed to the increased eNOS phosphorylation. This was confirmed by the loss of the vasorelaxant effect of tirofiban in the presence of l-NAME (eNOS inhibitor) and L-NMMA (NOS inhibitor) but not SMT (iNOS inhibitor) on isolated rat coronary arteries. The vasorelaxation was also blocked by the PI3K inhibitors, wortmannin and LY294002, as well as the Akt inhibitor SH-5, indicating the role of PI3K and Akt in tirofiban-mediated vasodilation. Moreover, further study showed that soluble guanylyl cyclase (sGC) inhibitor ODQ, or blockers of potassium channel (big-conductance calcium-activated potassium channel) blocked tirofiban-induced vasodilation of the coronary artery. These findings suggest that tirofiban induces vasorelaxation via an endothelium-dependent NO-cGMP signaling through the activation of the Akt/eNOS/sGC pathway.

Efficacy of Adenosine in Patients With Acute Myocardial Infarction Undergoing Primary Percutaneous Coronary Intervention: A PRISMA-Compliant Meta-Analysis

Whether adenosine offers cardioprotective effects when used as an adjunctive therapy for patients with acute myocardial infarction (AMI) undergoing primary percutaneous coronary intervention (PCI) remains controversial.To evaluate, via meta-analysis, the efficacy of adenosine in patients with AMI undergoing PCI.Randomized controlled trials (RCTs) published in Medline, Embase, and the Cochrane Central Register of Controlled Trials.RCTs of patients with AMI undergoing primary PCI, comparing adenosine treatment and placebo groups and reporting mortality, thrombolysis in myocardial infarction (TIMI) flow grade, myocardial blush grade (MBG), re-infarction, left-ventricular ejection fraction (LVEF), ST-segment elevation resolution (STR), recurrent angina, or heart failure (HF).Risk of bias was assessed by the Cochrane guidelines and publication bias by Egger's test. For studies reported in multiple publications, the most complete publication was used. Arms using different dosing schedules were merged. Mean differences (MDs) or risk ratios (RRs) were determined.Data were extracted from 15 RCTs involving 1736 patients. Compared with placebo, adenosine therapy was associated with fewer occurrences of heart failure (RR: 0.65, 95% confidence interval [CI]: 0.43-0.97, P[REPLACEMENT CHARACTER]=[REPLACEMENT CHARACTER]0.03) and no-reflow (TIMI flow grade <3, RR: 0.62, 95% CI: 0.45-0.85, P[REPLACEMENT CHARACTER]=[REPLACEMENT CHARACTER]0.003; MBG[REPLACEMENT CHARACTER]=[REPLACEMENT CHARACTER]0-1, RR: 0.81; 95% CI: 0.67-0.98, P[REPLACEMENT CHARACTER]=[REPLACEMENT CHARACTER]0.03), more occurrences of STR (RR: 1.19, 95% CI: 1.07-1.31, P[REPLACEMENT CHARACTER]<[REPLACEMENT CHARACTER]0.00001), but no overall improvement of LVEF (MD: 2.29, 95% CI: -0.09 to 4.67, P[REPLACEMENT CHARACTER]=[REPLACEMENT CHARACTER]0.06). Adenosine improved LVEF in the intravenous subgroup and the regular-dose intracoronary (IC) subgroup (0.24-2.25[REPLACEMENT CHARACTER]mg) compared with placebo (MD: 2.68, 95% CI: 0.66-4.70, P[REPLACEMENT CHARACTER]=[REPLACEMENT CHARACTER]0.009). Adenosine was associated with a poorer LVEF in the high-dose (4-6[REPLACEMENT CHARACTER]mg) IC subgroup (MD: -2.40; 95% CI: -4.72 to -0.09, P[REPLACEMENT CHARACTER]=[REPLACEMENT CHARACTER]0.04). There was no significant evidence that adenosine reduced rates of all-cause mortality, cardiovascular mortality or re-infarction after PCI.Adenosine dosage and administration routes, baseline profiles, and endpoints differed among included RCTs. Performance, publication, and reporting biases remain possible.Adenosine therapy appears to improve several outcomes in patients with AMI after PCI, but there is no evidence that adenosine can reduce mortality rates.

Adenosine and verapamil for no-reflow during primary percutaneous coronary intervention in people with acute myocardial infarction

BACKGROUND

Primary percutaneous coronary intervention (PPCI) is the preferred treatment for ST-segment elevation myocardial infarction. Although coronary flow is restored after PPCI, impaired myocardial perfusion (known as no-reflow) related to poor clinical outcomes is frequently observed. To overcome this phenomenon, drugs, such as atorvastatin, abciximab and others, have been tried as adjunctive treatment to PPCI. Among these drugs, verapamil and adenosine are among the most promising. No other systematic reviews have examined use of these two drugs in people with acute myocardial infarction (AMI) undergoing PPCI. This is an update of the version previously published (2013, Issue 6), for which the people of interest in the review were those treated with PPCI - not those given fibrinolytic therapy.

OBJECTIVES

To study the impact of adenosine and verapamil on no-reflow during PPCI in people with AMI.

SEARCH METHODS

We updated searches of the following databases in June 2014 without language restriction: the Cochrane Central Register of Controlled Trials (CENTRAL), MEDLINE, EMBASE, Web of Science and BIOSIS, China National Knowledge Infrastructure and clinical trials registers (ClinicalTrials.gov, Current Controlled Trials, Australian and New Zealand Clinical Trials Registry, the World Health Organization (WHO) International Clinical Trials Registry Platform). We also handsearched The American Journal of Cardiology.

SELECTION CRITERIA

We selected randomised controlled trials (RCTs) in which adenosine or verapamil was the primary intervention. Participants were individuals diagnosed with AMI who were undergoing PPCI.

DATA COLLECTION AND ANALYSIS

Two review authors collected studies and extracted data. When necessary, we contacted trial authors to obtain relevant information. We calculated risk ratios (RRs), P values and 95% confidence intervals (CIs) of dichotomous data.

MAIN RESULTS

We included in our review 11 RCTs (one new study with 59 participants) involving 1027 participants. Ten RCTs were associated with adenosine and one with verapamil. We considered the overall risk of bias of included studies to be moderate. We found no evidence that adenosine reduced short-term all-cause mortality (RR 0.61, 95% CI 0.25 to 1.48, P value = 0.27), long-term all-cause mortality (RR 0.78, 95% CI 0.22 to 2.74, P value = 0.70), short-term non-fatal myocardial infarction (RR 1.32, 95% 0.33 to 5.29, P value = 0.69) or myocardial blush grade (MBG) 0 to 1 after PPCI (RR 0.96, 95% CI 0.76 to 1.22, P value = 0.75). The incidence of thrombolysis in myocardial infarction (TIMI) flow grade < 3 after PPCI (RR 0.62, 95% CI 0.42 to 0.91, P value = 0.01) was decreased. Conversely, adverse events with adenosine, such as bradycardia (RR 6.32, 95% CI 2.98 to 13.41, P value < 0.00001), hypotension (RR 11.43, 95% CI 2.75 to 47.57, P value = 0.0008) and atrioventricular (AV) block (RR 6.78, 95% CI 2.15 to 21.38, P value = 0.001), were significantly increased.Meta-analysis of verapamil as treatment for no-reflow during PPCI was not performed because data were insufficient.

AUTHORS' CONCLUSIONS

It is difficult to draw conclusions because of the insufficient quality and quantity of current research studies. We considered the overall risk of bias of included studies to be moderate. Adenosine as treatment for no-reflow during PPCI could reduce angiographic no-reflow (TIMI flow grade < 3) but was found to increase adverse events. What's more, no evidence could be found to suggest that adenosine reduced all-cause mortality, non-fatal myocardial infarction or the incidence of myocardial blush grade 0 to 1. Additionally, the efficacy of verapamil for no-reflow during PPCI could not be analysed because data were insufficient. Further clinical research into adenosine and verapamil is needed because of the limited numbers of available trials and participants.

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.

Adenosine and verapamil for no-reflow during primary percutaneous coronary intervention in people with acute myocardial infarction

BACKGROUND

Primary percutaneous coronary intervention (PPCI) is the preferred treatment for ST segment elevation myocardial infarction. Although there is restoration of coronary flow after PPCI, impaired myocardial perfusion (known as no-reflow) is frequently observed, and is related to poor clinical outcomes. In order to overcome this phenomenon, drugs have been tried as adjunctive treatments to PPCI. Among them, verapamil and adenosine are two of the most promising drugs. There are no systematic reviews of these two drugs in people with acute myocardial infarction (AMI) undergoing PPCI.

OBJECTIVES

To study the impact of adenosine and verapamil on people with AMI who are undergoing PPCI.

SEARCH METHODS

We searched the following databases in February 2012: the Cochrane Central Register of Controlled Trials (CENTRAL) on The Cochrane Library, MEDLINE, EMBASE, Web of Science and BIOSIS, China National Knowledge Infrastructure, Clinical Trials registers (Clinical Trials.gov, Current Controlled Trials, Australian & New Zealand Clinical Trials Registry, the WHO International Clinical Trials Registry Platform). We also handsearched the American Journal of Cardiology.

SELECTION CRITERIA

We selected randomised controlled trials (RCTs) where adenosine or verapamil was the primary intervention. Participants were individuals diagnosed with AMI who were undergoing PPCI.

DATA COLLECTION AND ANALYSIS

Two review authors collected studies and extracted data. Where necessary, we contacted the trial authors to obtain the relevant information. We calculated risk ratios (RRs), P values, and 95% confidence intervals (CIs) of dichotomous data.

MAIN RESULTS

We included 10 RCTs involving 939 participants in our review. Nine RCTs were associated with adenosine and one with verapamil. We considered the overall risk of bias of included studies to be moderate. There was no evidence that adenosine reduced short-term all-cause mortality (RR 0.61, 95% CI 0.23 to 1.61, P = 0.32), long-term all-cause mortality (RR 1.20, 95% CI 0.27 to 5.22, P = 0.81), short-term non-fatal myocardial infarction (RR 1.38, 95% 0.28 to 6.96, P = 0.69) or the incidence of angiographic no-reflow (TIMI flow grade < 3 after PPCI: RR 0.72, 95% CI 0.49 to 1.07, P = 0.11, and myocardial blush grade (MBG) 0 to 1 after PPCI: RR 0.96, 95% CI 0.76 to 1.22, P=0.75). But the incidence of adverse events with adenosine, such as bradycardia (RR 6.57, 95% CI 2.94 to 14.67, P<0.00001), hypotension (RR 11.43, 95% CI 2.75 to 47.57, P=0.0008) and atrioventricular (AV) block (RR 6.67, 95% CI 1.52 to 29.21, P=0.01) was significantly increased.Meta-analysis of verapamil as treatment for no-reflow during PPCI was not calculated due to lack of data.

AUTHORS' CONCLUSIONS

We found no evidence that adenosine and verapamil as treatments for no-reflow during PPCI can reduce all-cause mortality, non-fatal myocardial infarction or the incidence of angiographic no-reflow (TIMI flow grade < 3 and MBG 0 to1), but there was some evidence of increased adverse events. Further clinical research into adenosine and verapamil is needed because of the limited numbers of included trials and participants.

The management of thrombotic lesions in the cardiac catheterization laboratory

Plaque rupture with superimposed thrombosis is the major mechanism of acute coronary syndromes. Although angiography underestimates the presence of thrombi, their detection is a poor prognostic indicator which is proportional to their size. Although emergent percutaneous coronary intervention (PCI) in the setting of ST elevation myocardial infarction (STEMI) and early PCI in the setting of unstable angina and non-STEMI were shown to be preferred strategies, the presence of angiographic thrombosis by virtue of causing micro and macro embolization can reduce the benefit of the intervention. Antiplatelet therapy especially using glycoprotein IIb/IIIa inhibitors reduces thrombus size, and improves myocardial perfusion and ventricular function. Routine manual aspiration prior to PCI in STEMI also improves myocardial flow and reduces distal embolization and improves survival. Distal embolic protection devices and mechanical thrombectomy do not have the same clinical benefits however, rheolytic thrombectomy may have a role in large vessels with a large thrombi.

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.

Intracoronary Vasodilators for the No-Reflow Phenomenon

Objective:

To review the literature relating to the use of intracoronary vasodilators to prevent and/or treat the no-reflow phenomenon in patients undergoing percutaneous coronary intervention (PCI).

Data Sources:

A literature search was conducted using MEDLINE (1966–March 2008) and Science Citation Index (1945–March 2008) using the search terms vasodilators, no-reflow, and intracoronary.

Study Selection and Data Extraction:

English-language clinical trials and case series were selected from articles retrieved. References of reviewed articles were examined for additional sources. Studies relating to the use of intracoronary vasodilators in the prevention and/or treatment of no-reflow in PCI were evaluated for safety and efficacy data. Articles relating to agents not available in the US were excluded.

Data Synthesis:

Evidence of intracoronary adenosine's utility in no-reflow treatment is limited. Its use in no-reflow prevention was associated with outcomes ranging from no difference to nearly an 88% reduction in no-reflow development; the drug was generally well tolerated. No-reflow treatment with intracoronary verapamil improved flow in 87–100% of cases. Preventive trials with verapamil failed to demonstrate efficacy. Atrioventricular block requiring treatment was the most commonly reported adverse event with intracoronary verapamil. Literature on intracoronary diltiazem and intracoronary nicardipine is limited. Both agents produced greater than 95% efficacy in no-reflow treatment, while prevention studies found no-reflow developing in less than 4% of patients. Although adverse event reporting was limited, hemodynamic instability was noted in patients receiving diltiazem. Response rates ranged from 73% to 100% when intracoronary nitroprusside was studied as treatment for no-reflow associated with acute myocardial infarction (AMI). Systemic hypotension was noted with nitroprusside administration.

Conclusions:

The available data are predominately from case series and retrospective reviews. Prevention of no-reflow with intracoronary vasodilators in elective PCI is not warranted. Nitroprusside should be considered first-line treatment in no-reflow associated with AMI.