Troponin Increases After Elective PCI Tied to Complexity, Extent of CAD

In the setting of elective PCI, postprocedural increases in cardiac troponin T detected by high-sensitivity assays are associated with greater complexity and extent of underlying coronary disease, new data show.

Prior research has linked more complex and extensive disease to poorer clinical outcomes, researchers led by Haitham Abu Sharar, MD (Heidelberg University Hospital, Germany), note in a study published recently online in Catheterization and Cardiovascular Interventions.

“Use of the [high-sensitivity] assay allows accurate monitoring of postprocedural myocardial injury and may identify patients at higher risk for ischemic events who may benefit from appropriate therapy [regimens], including a more potent platelet inhibition, a potential treatment approach which needs to be investigated in future randomized trials,” the authors conclude.

Commenting for TCTMD, Frederick Masoudi, MD (University of Colorado Anschutz Medical Campus, Aurora), highlights that an “important proportion” of patients undergoing elective PCI will develop some degree of myocardial injury after the procedure and that elevations of troponin may be related to the underlying burden of coronary disease.

He said some questions need to be resolved before this information would lead to changes in practice, however. “First of which is establishing what the biomarker-outcome relationship looks like using this higher-sensitivity standard,” Masoudi said.

Then the question is what can be done “beyond what is already done in patients with established coronary disease who have undergone elective stenting, which would include dual antiplatelet therapy, high-intensity statins, and other risk factor control,” he said. Use of different antiplatelet regimens could be an option, but Masoudi agreed with the researchers that that would have to be tested in future trials.

Shifting Definitions of Periprocedural MI

Elevations of cardiac troponin frequently occur after elective PCI, and the development of high-sensitivity assays has allowed for the detection of myocardial injury earlier and in a greater number of patients.

In this study, the investigators set out to identify patients with periprocedural MI (type 4a) or extensive myocardial injury following elective PCI and relate those troponin increases to the extent of coronary disease (by SYNTAX score) and the complexity of treated lesions (by the American College of Cardiology/American Heart Association classification). The analysis included 530 patients (mean age 70 years; 77.5% men) who were treated for stable CAD between April 2014 and March 2015 at Heidelberg University Hospital. About two-thirds had three-vessel disease, and 13.2% had prior CABG.

According to the SYNTAX score, after exclusion of those who had undergone CABG, 41.3% of patients were considered to have low risk, 35.4% intermediate risk, and 23.3% high risk. The complexity of the treated lesions was classified as A in 7.8%, B1 in 24.1%, B2 in 21.1%, C1 in 24.6%, and C2 in 22.4%.

Troponin levels were measured before and after PCI using a high-sensitivity cardiac troponin T assay with a 99th percentile upper reference limit of 14 ng/L. Median level at baseline was 11 ng/L, with about two-thirds of patients coming in below the 99th percentile. Those who had elevated levels at baseline—about one-third of the cohort—tended to be older and to have worse systolic LV function and renal function.

Myocardial injury and periprocedural MI were defined according to both the second and third universal definitions of MI, which differ in that the third iteration increases the troponin level needed to define periprocedural MI and adds a requirement for other indicators of ischemia. Thus, more patients with troponin elevations are defined as having myocardial injury rather than type 4a MI under the latter criteria.

Among patients with normal baseline troponin levels, the rate of periprocedural MI was 27.5% using the second definition and 4.2% using the third. The corresponding figures in patients with elevated baseline troponin levels were 79.2% and 15.6%.

Postprocedural increases in troponin correlated with both the complexity of the treated coronary lesions and the extent of disease (P < 0.05 for both).

More Potent Therapy Needed?

Abu Sharar et al note that there is debate about the prognostic significance of periprocedural MI. They point out, however, that most studies have shown a relationship between its occurrence and worse clinical outcomes.

“Thus, it may be of prognostic importance to monitor these occurrences, preferably through serial high-sensitivity cardiac troponin measurements,” they write. “Since the level of cardiac troponin elevation correlates directly with the extent of myocardial injury, and . . . related impaired clinical outcome, appropriate medical therapy [regimens] aiming at reducing ischemic events in patients undergoing elective PCI may have a positive clinical impact.”

Dual antiplatelet therapy with aspirin and clopidogrel might not be sufficient after elective PCI, they suggest, because of shortcomings of clopidogrel that include “individual variation in response to loading or during maintenance, delayed onset of action, and lower inhibition of platelet aggregation as compared with the newer and more-potent antiplatelet drugs such as ticagrelor and prasugrel.”

Those drugs have been shown to reduce ischemic events without increasing major bleeding in patients with ACS, and “this may be also an appealing option in reducing periprocedural ischemic incidents and subsequent myocardial injuries or necrosis in the setting of an elective PCI, especially for severe coronary atherosclerosis burden or complex lesions,” Abu Sharar and colleagues propose, encouraging future trials to explore this question.

For now, Masoudi said, adherence to guideline-recommended approaches is the way to go when it comes to managing patients after elective PCI.

“This doesn’t to me represent data that would or should change practice at this point,” he said. “There’s a lot more that would need to be known about the prognostic implications of specific levels of elevations of high-sensitivity troponin, particularly in those patients who don’t have an otherwise clinically apparent injury, [along with] some evidence for the benefits of an alternative therapeutic route in those patients who do have these elevations before we might consider diverting from what the current guidelines suggest.”