Mortality Benefit with Primary PCI vs. Thrombolysis Restricted to High-Risk Patients

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Primary percutaneous coronary intervention (PCI) for ST-segment elevation myocardial infarction (STEMI) reduces in-hospital mortality compared with a strategy of initial thrombolysis. However, the benefit is restricted to high-risk patients, and the gap between the 2 procedures has narrowed in recent years. Results from a large Belgian study appear in the March 28, 2011, issue of Archives of Internal Medicine.

Researchers led by Marc J. Claeys, MD, PhD, of University Hospital Antwerp (Antwerp, Belgium), looked at 5,295 STEMI patients stratified by TIMI risk profile (low, intermediate, and high) who were treated by primary PCI (n = 4,574) or thrombolysis (n = 721) from July 1, 2007, through December 31, 2009, at 73 Belgian hospitals. The majority of the thrombolysis patients (83.6%) received subsequent invasive evaluation.

The overall in-hospital mortality rate was 6.0%, with a similar incidence between the primary PCI (5.9%) and thrombolysis (6.6%) groups (P = 0.40). When compared according to risk profile, high-risk patients receiving primary PCI showed a relative reduction in mortality of 45.7% compared with thrombolysis, but intermediate- or low-risk patients fared equally well with either procedure (table 1).

Table 1. In-Hospital Mortality

Primary PCI remained an independent predictor of lower in-hospital mortality in TIMI high-risk patients (OR 0.54; 95% CI 0.30-0.90). Independent predictors for higher in-hospital mortality were age, Killip class greater than 1, low blood pressure, use of CPR, history of PAD, longer treatment delay, anterior infarction location, and female sex.

Among the primary PCI patients, more than half (56%) were treated early, with a door-to-balloon (D2B) time less than 60 minutes. Roughly one-third (33.1%) had intermediate D2B times ranging from 60 to 120 minutes, and relatively few (8.6%) were treated after 120 minutes. Rates in the thrombolysis group for early (< 30 min), intermediate (30-60 min), and late (> 60 min) door-to-needle times were 48.0%, 18.6%, and 19.8%, respectively.

Subgroup analysis revealed that the mortality benefit of primary PCI over early thrombolysis was offset if the door-to-balloon time exceeded 60 minutes.

“Our findings indicate that the mortality benefit of [primary] PCI compared with thrombolysis in STEMI patients has been substantially attenuated, particularly in the low- and intermediate-risk groups and most likely because of improved outcomes of thrombolysis,” Dr. Claeys and colleagues write. “Higher use of invasive evaluation after thrombolytic therapy . . . might explain this favorable mortality trend.”

Elderly Gain the Most

The authors added that the higher-risk patients who will benefit most from primary PCI represent about 20% of the STEMI population, consisting mainly of elderly patients with hemodynamic instability. Overall, the study supports current guidelines, they note, which advocate early administration of lytic therapy when PCI is unavailable, followed by planned early angiography.

Sorin J. Brener, MD, of Weill Cornell Medical College (New York, NY), agreed. “The study reinforces that for patients who arrive at hospitals that are equipped for primary PCI 24 hours a day, that is the preferred method of reperfusion,” he told TCTMD in a telephone interview. “On the other hand, for patients who arrive at a hospital that is not equipped for primary PCI all the time, lytics are an excellent alternative, which should be followed immediately by transfer to a PCI-capable hospital. This way, if the lytics don’t work properly, the patient has access to a cath lab and can have rescue PCI if necessary.”

Dr. Brener stressed, however, that “what we should not take away from this is that it’s okay to keep the patient in the hospital without a cath lab and give them lytics and just assume they’ll work.”

Access to Urgent PCI the Exception, Not the Rule

The study should come as reassuring news to institutions with limited access to urgent PCI facilities, the authors note, especially since the hospital penetration rate of PCI is still under 50% in many regions in Europe and the United States.

According to Dr. Brener, the US rate is even lower. “Only about 20% of US hospitals have an operational cath lab 24 hours a day, so the majority of centers are absolutely in this situation,” he said.

Dr. Brener cautioned that the study is not randomized, meaning that clinicians chose the procedure they judged best for each patient. “So the study shows that when properly selected, you can achieve good results with both techniques,” he said. “Also, the study is looking at a very short follow-up period. If they had looked at 2, or 3, or 6 years later, they would see that actually, the benefit of angioplasty is substantial.”

Nevertheless, it is clear that thrombolysis as an initial strategy has become acceptable in recent years in lower risk patients. “There’s been so much improvement in pharmacology, not just in the lytics themselves, but also in the additional medications that patients receive, like statins,” Dr. Brener said. “Also, the invasive evaluation to make sure there aren’t other things that need to be fixed beyond the immediate reperfusion is very important.”

According to the authors, this practice has increased from roughly 30% of cases 10 years ago to over 80% in the current study.

 

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Source:
Claeys MJ, de Meester A, Convens C, et al. Contemporary mortality differences between primary percutaneous coronary intervention and thrombolysis in ST-segment elevation myocardial infarction. Arch Intern Med. 2011;171:544-549.

 

 

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