Ischemic Conditioning Improves Long-term Outcomes in STEMI Patients

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Remote ischemic conditioning using a blood pressure cuff in the ambulance prior to percutaneous coronary intervention (PCI) improves long-term outcomes in patients with ST-segment elevation myocardial infarction (STEMI). Results of a randomized trial were published online September 12, 2013, in the European Heart Journal.

Researchers led by Astrid D. Sloth, MD, of Aarhus University Hospital (Aarhus, Denmark), randomized 333 patients with a suspected first acute STEMI from February 2007 to November 2008 to primary PCI with (n = 166) or without (n = 167) remote ischemic conditioning. The conditioning procedure was performed in the ambulance using intermittent arm ischemia via 4 cycles of 5-minute inflation followed by 5-minute deflation of a blood-pressure cuff.

Over a median follow-up of 3.8 years, per-protocol analysis showed that MACCE (all-cause mortality, MI, readmission for heart failure, and ischemic stroke/TIA) were almost half as frequent in the remote conditioning group as in controls. All-cause mortality was also lower in the conditioning group, while cardiac mortality was equivalent between groups and noncardiac mortality showed a trend for reduction in the preconditioning arm (table 1).

Table 1. Long-term Outcomes, Per-Protocol Analysis

 

Conditioning Plus PCI
(n = 126)

PCI
(n = 125)

HR (95% CI;
P Value)

MACCE

13.5%

25.6%

0.49; 0.27-0.89;
0.018

All-Cause Mortality

4.0%

12.0%

0.32; 0.12-0.88;
0.027

Cardiac Mortality

1.6%

4.0%

0.39; 0.08-2.00;
0.258

Noncardiac Mortality

2.4%

8.0%

0.28; 0.08-1.03;
0.056


The endpoint for MACCE was reduced independently of vessel patency prior to the procedure as well as infarct location. The intention-to-treat analysis supported the per-protocol analysis (table 2), though the results were not as strongly significant.

Table 2. Long-term Outcomes, Intention-to-Treat Analysis

 

Conditioning Plus PCI
(n = 166)

PCI
(n = 167)

HR (95% CI;
P Value)

MACCE

18.1%

27.5%

0.62; 0.39-0.99;
0.045

All-Cause Mortality

6.6%

12.6%

0.51; 0.25-1.07;
0.074

Cardiac Mortality

2.4%

5.4%

0.44; 0.13-1.41;
0.167

Noncardiac Mortality

4.2%

7.2%

0.57; 0.23-1.45;
0.241


The researchers say the study is the first to evaluate the effect of remote ischemic conditioning as an adjunct to primary PCI on long-term clinical outcomes in patients with AMI. The results, Dr. Sloth and colleagues affirm, are “encouraging” suggesting that “a simple, cost-effective intervention, which can easily be applied in the prehospital setting in patients with acute cardiac events, may in fact have the potential to reduce morbidity and mortality.”

Although the exact mechanism by which remote ischemic preconditioning provides benefit is unclear, there are several theories.

One possibility is that preconditioning 1 organ stimulates the release of a humoral factor, which some studies suggest is a low-molecular-weight substance and others suggest involves adenosine. Another hypothesis is that preconditioning stimulates neural reflexes. But many researchers believe the process is actually multifactorial, involving both mechanisms and potentially others as well.

 


Source:
Sloth AD, Schmidt MR, Munk K, et al. Improved long-term clinical outcomes in patients with ST-elevation myocardial infarction undergoing remote ischaemic conditioning as an adjunct to primary percutaneous coronary intervention. Eur Heart J. 2013;Epub ahead of print.

 

 

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Disclosures
  • The work was supported by the Danish Council for Strategic Research and Foundation Leducq.
  • Dr. Sloth reports no relevant conflicts of interest.

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