Medication Compliance May Impact Revascularization Outcomes

Medication compliance appears to have an important impact on long-term outcomes following coronary revascularization, with differences according to the type of procedure, a new study shows. The findings may have implications for the choice of PCI or CABG in patients known to have trouble sticking to their drug regimens.

“Regardless of what interventional therapy you receive, adherence to evidence-based medical therapy can have a dramatic impact on long-term survival and freedom from major adverse cardiac events,” the study’s lead author, Paul Kurlansky, MD (Columbia University, New York, NY), told TCTMD.

According to Kurlansky, adherence to medical therapy has been largely ignored in outcomes research in this patient population for reasons ranging from logistical issues in long-term tracking to how noncompliance occurs and whether it is periodic or permanent.

“Because it is such a difficult thing to study, it really hasn’t been studied in this context, comparing PCI with CABG, even though PCI vs CABG has been studied extensively,” Kurlansky said.

In a paper published online October 24, 2016, ahead of print in Circulation, Kurlansky and his team examine data from the multicenter CARE registry, which included patients who underwent CABG (n = 973) or PCI (n = 2,255) in 2004. Detailed medication histories were obtained from each patient at 18 months and again at a long-term follow-up that occurred between 5 and 7 years after revascularization.

Compared with patients who were not still on antiplatelets, lipid-lowering agents, or beta blockers at both follow-up time points, those who were fully compliant had better MACE-free survival regardless of whether they underwent PCI or CABG. Additionally, among noncompliant patients, those in the CABG group had better MACE-free survival compared with those in the PCI group (log-rank P = 0.001).

Looking at the entire cohort, noncompliance to medication was a greater predictor of MACE–free survival than choice of medical therapy (HR 2.79; 95% CI 2.19-3.54). Further analysis to look for interactions between choice of revascularization and adherence or nonadherence to therapy also showed an advantage for CABG over PCI when patients were noncompliant (HR 1.88; 95% CL, 1.49-2.38), but no such advantage for compliant patients.

According to Kurlansky and colleagues, the study implications “are far-reaching from both a clinical and a scientific point of view.”

In terms of patient selection, for example, they note that patients who are unlikely to comply with strict medication regimens after PCI may do better with surgery, while PCI might be more appropriate for those who are likely to diligently take their prescribed medications.

To TCTMD, Kurlansky added that researchers need to focus more on the issue of medication compliance and how it may be impacting long-term outcomes. While the study findings are preliminary, he said he hopes they may encourage physicians to at least have a more comprehensive dialogue with their patients on a frequent basis about factors such as their support structure at home and their daily medication regimens, even though gauging compliance is “an imperfect science.”

Not Necessarily Causal Relationships

In an email to TCTMD, Sunil V. Rao, MD (Duke University Medical Center, Durham, NC), stressed that while the hypothesis “makes sense,” the study’s observational nature means that “what they are reporting are associations and not necessarily causal relationships.” Multiple reasons, he added, may account for these associations.

“For example, patients with poor adherence likely have more advanced CAD, and we know from the SYNTAX trial that CABG is superior to PCI in patients with more complex CAD. There was an interesting study that came out of the CHARM trial (CHF trial with candesartan) showing that poor adherence was a predictor of poor outcome even when the patient was randomized to placebo. So, there are some unmeasured confounders that go along with poor adherence,” Rao noted.

Like Kurlansky, he said the practical message from all this is to continually reinforce the importance of medication adherence, as well as adherence to other secondary prevention measures such as exercise, diet, and smoking cessation.

“We know that many patients prefer PCI to a surgical procedure, so in cases where PCI is feasible and the patient is refusing surgery, it is important to incorporate the message about adherence into the conversation with the patient,” Rao said.

Kurlansky concluded that if further studies confirm his findings, they may have implications for personalized therapy regimens after revascularization. In particular, patients who have undergone PCI may require medical therapy that addresses the remodeling process, while those who have had surgery may require medications that have a direct impact on graft patency.