Ischemic Preconditioning Reduces Myocardial Necrosis in Elective PCI

Download this article's Factoid (PDF & PPT for Gold Subscribers

 

Remote ischemic preconditioning, by repeated blood pressure cuff inflation, reduces myonecrosis as assessed by cardiac troponin release following elective percutaneous coronary intervention (PCI), according to a single-center randomized trial published online June 18, 2013, ahead of print in Catheterization and Cardiovascular Interventions.

Researchers led by Tahir I. Mohamed, MD, of DMC Cardiovascular Institute, Harper University Hospital (Detroit, MI), randomized 149 consecutive patients admitted for elective PCI at Dar Al Fouad Hospital (Giza, Egypt) between March and November 2010 to remote preconditioning (n = 77) or control therapy (n = 72) in which a deflated pressure cuff was placed around the nondominant arm. Preconditioning consisted of 3 5-minute cycles of arm ischemia alternating with 5 minutes of reperfusion in the preprocedure area immediately before transfer to the cath lab. This was achieved by inflating a blood pressure cuff to 200 mm Hg around the nondominant upper arm.

There were no significant differences between the 2 groups regarding use of DES, stent length, pre- or post-stent dilation, side branch compromise, dissection, or final TIMI flow.

Troponin T Values Show Change, Secondary Endpoints Unaltered

Post procedural mean cardiac troponin T values (the primary endpoint), were lower in patients receiving remote preconditioning, while postprocedural MI showed a reduced trend in the preconditioning group. Other secondary endpoints, though, such as CK-MB and CRP values, were unaffected (table 1).

Table 1. Mean Postprocedural Endpoints

The authors cite previous research reporting that up to 40% of patients undergoing PCI have post-PCI myocardial injury, and while these troponin elevations have been deemed by some to be merely “troponin leaks,” with no impact on clinical or angiographic outcomes, others have found a relationship between the magnitude of biomarker elevation and clinical outcomes.

Multiple Hypotheses Suggested

Dr. Mohamed and colleagues cite several mechanisms to explain the cardioprotective effect of remote ischemic preconditioning:

• Neural hypothesis: Preconditioning of the organ or tissue remote from the heart generates an endogenous substance such as adenosine, bradykinin, or calcitonin gene-related peptide that then activates a local afferent neural pathway stimulating an efferent neural pathway that terminates at the heart and mediates cardioprotection
• Humoral hypothesis: The endogenous substance or some other unidentified humoral factor generated in the remote organ or tissue enters the bloodstream and activates its respective receptor in the myocardium thereby recruiting intracellular pathways of cardioprotection implicated in ischemic preconditioning
• Systemic hypothesis: Transient ischemia and reperfusion of an organ or tissue provokes a systemic protective response, potentially combining anti-inflammatory and antiapoptotic effects

Regardless, the authors conclude, “[remote ischemic preconditioning] is a simple, cheap, well-tolerated procedure that may potentially have a significant effect in the reduction of postprocedural elevation of [cardiac troponin T]. Further assessment in larger, more adequately powered randomized studies is needed to confirm the results of our study.”

In an e-mail communication with TCTMD, Stephen P. Hoole, MD, of Papworth Hospital (Cambridge, United Kingdom), noted that “there remains controversy in the interventional community whether a small ‘troponin leak’ following an otherwise uncomplicated PCI is clinically significant, despite evidence that it results from myonecrosis. However, it is generally accepted that larger PCI-induced troponin elevations (to levels > 5x ULN, as specified in the 3rd Universal Definition of MI, 2012) cause detrimental clinical outcomes. Recent data from our group have shown that even small reductions in PCI-related troponin release after [remote ischemic preconditioning] do translate to better clinical outcomes in the medium and long term for patients undergoing elective PCI.”

Still, larger, confirmatory trials will likely be needed “to assess the effect of [remote preconditioning] on clinical outcomes . . .  [and] to convince clinicians to apply [remote preconditioning] in their elective PCI practice,” Dr. Hoole said.

 

---

Source:
Ahmed RM, Mohamed E-HA, Ashraf M, et al. Effect of remote ischemic preconditioning on serum troponin T level following elective percutaneous coronary intervention. Catheter Cardiovasc Interv. 2013;Epub ahead of print.

 

Disclosures:

• Drs. Mohamed and Hoole report no relevant conflicts of interest.

 

Related Stories:

• Remote Preconditioning Prior to PCI Demonstrates Long-term Ischemic Benefits
• Ischemic Preconditioning Limits Contrast-Induced Kidney Damage
• Ischemic Preconditioning Beneficial Prior to PCI