Cardiac Stress Imaging at 5 Years Post-PCI Holds Prognostic Value

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Routine use of stress myocardial perfusion scintigraphy (MPS) at 5 years after percutaneous coronary intervention (PCI) picks up signs of disease in more than half of patients, according to an observational study published online May 14, 2014, ahead of print in JACC: Cardiovascular Interventions. Whether or not patients are symptomatic at the time of testing, abnormal findings are associated with increased risk of adverse events, primarily related to persistent or progressing disease in remote cardiac vessels.

For the prospective BASKET LATE IMAGING study, researchers led by Michael J. Zellweger, MD, of University Hospital (Basel, Switzerland), looked at 339 patients who survived to 5 years after successful stent implantation in the BASKET trial and consented to undergo protocol-mandated MPS at that time as well as subsequent evaluation irrespective of symptoms. Patients were aged 72 ± 10 years, and 18% were women.

With or Without Symptoms, Abnormal Findings Predict MACE

Ninety percent of patients were angina-free at 5 years, yet 60% had abnormal MPS findings. Among the 205 patients with defects on MPS, 67.8% had fixed (scar) and 28.2% had reversible (ischemia) defects, with 3.9% showing a combination of fixed and reversible. Of the reversible perfusion defects, 55% were due to initially treated vessels, 33% to remote regions, and 12% to both.

Over a follow-up period of 3.7 ± 0.3 years, there were 7 cardiac deaths, 18 MIs, and 47 repeat revascularizations (38 PCI and 9 CABG). Annual rates of cardiac death and MACE were 0.6% and 4.4%, respectively. In patients with normal MPS findings, annual rates of cardiac death and MACE were 0.2% and 3%, respectively.

Compared with those with normal findings, patients with abnormal MPS results had higher risk of MACE (HR 1.95; 95% CI 1.06-3.59; P = .032) and a trend toward increased cardiac death/MI (HR 2.50; 95% CI 0.93-6.69; P = .066) but showed no increase in cardiac death alone. MACE rates were similar regardless of whether abnormal MPS patients had symptomatic or silent ischemia (36% vs 27%; P = .610), with both groups showing higher risk than patients with normal MPS findings (11%; P < .05 for both comparisons).

On Cox regression analysis, remote ischemia independently predicted MACE (HR 4.1; 95% CI 1.97-8.37; P < .001) whereas treated-vessel ischemia did not.

Time Horizon of Screening Key

According to the researchers, the current results “emphasize the importance of long-term secondary prevention of CAD and call for a randomized controlled trial to define the optimal management of patients with ischemia very late after revascularization, irrespective of symptoms, and [to assess] its cost-benefit implications.”

Ajay J. Kirtane, MD, SM, of Columbia University Medical Center (New York, NY), predicted to TCTMD that such a trial is unlikely but said that the strategy employed here has merit. Though routine stress testing was recently listed by the Society for Angiography and Cardiovascular Interventions as one of the ‘Top 5’ interventional procedures to avoid, the current paper describes a different approach, he said in a telephone interview.

The “time horizon” is relevant, Dr. Kirtane explained, in that BASKET performed MPS at 5 years rather than only a few years after PCI. “In fact, if you look at the guidelines, even after bypass surgery, once you get 5 years out, just by virtue of the fact that people have extensive disease, other [issues] can crop up and these patients over time are higher risk,” he said.

Making informed treatment decisions over the long-term in patients with stable ischemic heart disease is challenging, he continued. “When we’re looking longitudinally at how patients do over time, once you get beyond 5 years, it starts becoming an area where we don’t have a lot of prospective data. In that regard, this study is informative.”

When it comes to asymptomatic patients, Dr. Kirtane reported that his decision to screen after PCI varies. More sedentary patients might be more likely to have unrecognized disease, as they do not often exert themselves enough to show symptoms, he explained, noting that it is unclear in the current study exactly what “asymptomatic” means.

Moreover, “stress testing is not solely about the SPECT perfusion defect” and usually integrates other metrics such as exercise capacity, he added.

 

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Source:
Zellweger MJ, Fahrni G, Ritter M, et al. Prognostic value of “routine” cardiac stress imaging five years after percutaneous coronary intervention: the prospective long-term observational BASKET LATE IMAGING study. J Am Coll Cardiol Intv. 2014;Epub ahead of print.

 

 

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