CvLPRIT Substudy Finds Little Lasting Damage From Non-Infarct Artery PCI


Concern that complete revascularization of STEMI patients with multivessel disease might lead to an uptick in periprocedural MI compared with infarct-artery PCI may be somewhat dispelled by new findings from the CvLPRIT’s cardiac magnetic resonance (CMR) substudy. While the early rise in MIs does exist, the data show, such events do not increase the amount of damaged heart muscle 9 months later.

CvLPRIT Substudy Finds Little Lasting Damage From Non-Infarct Artery PCIPCI outside the infarct-related artery (IRA) “is associated with additional infarction. However, these type 4a MIs are relatively infrequent, generally small, and did not result in an increase in total infarct size,” write Gerry P. McCann, MD, of the University Hospitals of Leicester National Health Service Trust, Glenfield Hospital (Leicester, England), and colleagues.

“There is mounting evidence from randomized trials,” they say, “that treating multivessel disease with complete revascularization leads to a reduction in MACE after [primary] PCI compared with an IRA-only strategy.”

CvLPRIT, originally presented at the 2014 ESC Congress, randomized 297 STEMI patients presenting at 7 UK centers within 12 hours of symptom onset to receive primary PCI in the IRA only or also in any significantly blocked non-IRAs, ideally within the same procedure but at least during the index hospitalization. At 12 months, the risk of MACE (primary endpoint; total mortality, recurrent MI, heart failure, and ischemia-driven revascularization) calculated by time to first event was 55% lower in the complete revascularization group.

For the analysis published in the December 22 issue of the Journal of the American College of Cardiology, researchers focused their attention on the 203 patients who completed predischarge CMR (median day 3).

CMR Tracks Infarcts, Their Consequences

Patient characteristics were well-matched between treatment arm. Pre-discharge, patients in the complete revascularization group had similar total infarct size but were more likely to show signs of non-IRA MI on CMR. The acute non-IRA MIs that did occur were larger in the complete vs IRA-only groups. At approximately 9-month follow-up, patients assigned to complete revascularization again were more likely to show signs of infarction, though there were no differences in total infarct size. Additionally perfusion imaging showed ischemic burden to be similar in both groups.

Table. CvLPRIT Substudy Finds Little Lasting Damage From Non-Infarct Artery PCI

By 12-month follow-up, there was a borderline difference in MACE favoring the complete-revascularization group than for the IRA-only group at 8.2% vs 17.1% (P = .055). Patterns were similar to what was seen in the overall CvLPRIT trial.

Reassuring But Not Yet COMPLETE

In an editorial, Eric Larose, DVM, MD, of Laval University (Quebec City, Canada) agrees with the study authors that the lack of difference seen here in total infarct size at follow-up is “reassuring” but also expresses some reservations about complete revascularization.

Restricting primary PCI to the IRA, he argues, “makes sense, because an unforeseen complication during intervention in the non-IRA territory would add insult to injury by transforming a single-territory event into a multiple territory one: at the very least, more widespread myocardial stunning, and at the worse, greater myocardial necrosis at a time of looming instability during an acute syndrome.” As such, “it simply does not appear reasonable to take this added risk.”

Larose also points to the “apparent discordance” between the increase in multiple territory infarcts and the absence of an increase in total infarct size.

“There is little mechanistic evidence to support such a discrepancy, [warranting] corroboration in a larger sample,” he suggests. “Furthermore, although the presumed benefit of [complete revascularization] has long been decreased ischemic burden, this study fails to identify any [between-group difference] at 9 months.

“Such unexpected findings highlight important gaps in our knowledge and the importance of future trials to better inform clinical decisions,” Larose concludes. At issue is the optimal timing of non-IRA PCI, whether complete revascularization is beneficial only to certain subgroups, how lesion characteristics might provide guidance, and which specific drugs, devices, and methods are preferred. The COMPLETE trial, he suggests, may offer some answers.


Sources: 
1. McCann GP, Khan JN, Greenwood JP, et al. Complete versus lesion-only primary PCI: the randomized cardiovascular MR CvLPRIT substudy. J Am Coll Cardiol. 2015;66:2713-2724.
2. Larose E. Guilty as sin: revisiting Sutton’s Law in ST-segment elevation myocardial infarction [editorial]. J Am Coll Cardiol. 2725-2727.

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Disclosures
  • The CMR substudy was funded by the Medical Research Council and managed by the NIHR Efficacy and Mechanism Evaluation program, and the main CvLPRIT trial was funded by the British Heart Foundation with support from the NIHR Comprehensive Local Research Networks.
  • McCann reports being funded by an NIHR research fellowship and receiving research grants from Menarini International, Novartis, and Servier.

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