高齢者には初期治療としてのPCIは血栓溶解療法よりも有効性が高い

Primary angioplasty is superior to thrombolysis in the treatment of very old patients with acute myocardial infarction (AMI), according to results from the TRIANA (TRatamiento del Infarto Agudo de miocardio eN Ancianos) study, a randomized trial sponsored by the Spanish Society of Cardiology.

The trial was designed to compare the two principal available treatments to open blocked coronary arteries in AMI patients: immediate primary PCI with angioplasty, and thrombolysis with clot-dissolving drugs. The trial was performed in 226 patients all aged 75 years or older and all with acute myocardial infarctions (AMIs) of less than six hours' evolution. They were recruited in 23 Spanish hospitals between 2005 and 2007.

The study, which was closed prematurely because of slow patient recruitment, found no differences between the two groups in its primary endpoint ― the incidence of death, reinfarction or disabling stroke at 30 days (25.4% in the thrombolysis group and 18.9% in the primary angioplasty group, p=0.21). Despite the higher-than-anticipated rate of events in both arms, the study became underpowered to detect such differences because of its reduced recruitment. However, in a pre-specified secondary endpoint there was a significantly lower need of new catheterization for recurrent cardiac ischemia in the primary angioplasty arm (0.8% versus 9.7%, p<0.001).

Reviewing the findings principal investigator Professor Hector Bueno from the Hospital General Universitario "Gregorio Maranon" in Madrid reported that:

• The effect of primary angioplasty on reducing recurrent ischemia was so strong that it could still be easily detected in the study, despite its limited statistical power.
• Contrary to what might have been anticipated, there was no clear evidence that thrombolysis, which is considered controversial in older patients because of their increased bleeding risk, was unsafe in a population whose median age was 81 years; the study found no intracranial bleeding directly related to the use of thrombolysis, and no significant differences between groups in major bleeding (4.5% versus 3.8%; p=0.78), or need for transfusions (3% vs. 5.3%, p=0.35).
• There was no increase in renal failure associated with primary angioplasty (6.1% versus 7.5% with thrombolysis), a feared complication of catheterization in older patients.

Professor Bueno added: "All efficacy outcomes showed concordant trends in favor of primary angioplasty, suggesting that the potential advantage of an invasive strategy over thrombolysis in very old patients is because of its greater efficacy rather than its superior safety. However, patients in both groups tended to have a comparable prognosis one year later."