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About one-quarter of patients with stable coronary artery disease (CAD) are prescribed dual antiplatelet therapy (DAPT), probably due to factors such as MI or revascularization within recent years, diffuse atherosclerosis, and DES implantation,according to a registry study published online June 23, 2014, ahead of print in the American Heart Journal. Nonetheless, these patients are no more likely to be protected against future ischemic events than those receiving aspirin or clopidogrel alone.

How DAPT Patients Differ

The cohort was divided into those who on entry were receiving either a single antiplatelet agent (n = 2,047 on aspirin and n = 776 on clopidogrel) or DAPT (n = 868).

On multivariate analysis, factors associated with long-term DAPT use were:

• Younger age
• Persistent angina at inclusion
• Higher BMI
• MI 1 to 3 years prior
• Multivessel CAD
• Prior DES implantation
• Prior CABG
• Prior aortic or peripheral intervention
• Lower LVEF

Over a 2-year follow-up period, the composite of cardiovascular death, MI, or stroke (primary endpoint) occurred in 4.8% of patients, and 0.8% experienced a bleeding event defined as Bleeding Academic Research Consortium (BARC) type 3 or higher. In particular, there were 192 deaths (71 from cardiovascular causes), 86 MIs, and 34 strokes.

No difference was seen between the single and dual antiplatelet therapy groups for the primary composite endpoint or the individual endpoints with the exception of MI, which was higher in the DAPT group (table 1).

Table 1. Two-Year Outcomes

After propensity-score matching, the 2 groups (n = 824 each) had similar rates of all endpoints, with the composite endpoint and bleeding rising steadily over the study period. The results were consistent across multiple subgroups.

The authors say the study reflects “a contemporary management of CAD patients,” and comment that “the proportion of patients on DAPT (24%) was relatively high despite no clear recommendation for such a prescription in stable patients.”

Dr. Lemesle and colleagues say that although the results do not support use of long-term DAPT in this cohort, “very high-risk patients with anatomical particularities (including multiple or very long stenting, left main stenting) or history of previous [stent thrombosis] for example may still benefit” from such therapy. Moreover, the strategy appears to be safe provided patients are thoroughly assessed for bleeding risk. However, they add, this approach should be the exception rather than the rule.

A Rationale for Prolonged DAPT in the Absence of Randomized Support

In a telephone interview with TCTMD, Sorin J. Brener, MD, of Weill Cornell Medical College (New York, NY), said the prevalence of DAPT use in stable patients in CORONOR is probably in line with US practice. 

The randomized CHARISMA trial, which overall found DAPT no more effective than aspirin in preventing ischemic events after a median 28 months, was “either neutral or positive, depending on how you look at it,” he said, “but certainly patients who had symptomatic disease did better with DAPT than single antiplatelet therapy.”

One important—and unfortunate—difference between CHARISMA and the registry study, he noted, is the median interval from initial event to enrollment (about 1 year vs a median 4 years), marking CORONOR’s population as clearly more stable. That factor may account for the low rate of events in the latter study, he added.

Dr. Brener said he is among a minority of physicians who maintain patients with established CAD on DAPT indefinitely if they do not bleed and can afford the cost. “If you believe that DAPT passivates the vessel, as I do, it potentially prevents future events. It’s not because of any stents patients have, it’s because of their atherosclerosis,” he asserted. Acknowledging that the practice is not sanctioned by guidelines, he said he tells patients, “We’re not sure [DAPT] helps, but if you tolerate it well, then it makes sense to keep you on it.”

The current study reinforces the need for randomized trials to assess the usefulness of prolonged DAPT, either with clopidogrel or newer thienopyridines, Dr. Brener said. The large DAPT trial, in which 1 arm received the therapy for up to 30 months past DES implantation, will report results by the end of the year, he noted.

 Source: 
Lemesle G, Lamblin N, Meurice T, et al. Dual antiplatelet therapy in patients with stable coronary artery disease in modern practice: prevalence, correlates and impact on prognosis (from the CORONOR study). Am Heart J. 2014;Epub ahead of print.

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