Patients with complex coronary artery disease (CAD) – either three-vessel disease and/or left main disease – who also had heavy coronary artery calcification (CAC) had greater all-cause mortality 10 years after revascularization, compared with those without such lesions.
However, perhaps unexpectedly, patients with heavily calcified lesions (HCLs) had similar 10-year survival whether they had undergone coronary artery bypass grafting (CABG) or percutaneous coronary intervention (PCI).
These findings from a post hoc analysis of the SYNTAX Extended Survival (SYNTAXES) study led by Hideyuki Kawashima, MD, PhD, National University of Ireland, Galway, and the University of Amsterdam, were published online Dec. 29, 2021, in JACC: Cardiovascular Interventions.
“There was an apparent lack of benefit at very long-term with CABG versus PCI in the presence of HCL,” Dr. Kawashima and corresponding author Patrick W. Serruys, MD, PhD, National University of Ireland and Imperial College London, summarized in a joint email to this news organization.
“Since HCLs – the final status of atherosclerosis and inflammation – reflect the aging process, complexity, and extensiveness of CAD, and comorbidity, it is possible that the currently available revascularization methods do not provide benefit in the prevention of long-term [10-year] mortality,” they suggested.
In an accompanying editorial, Usman Baber, MD, commented that this study provides a “novel insight.”
Specifically, while patients without HCLs had significantly lower 10-year mortality with CABG versus PCI (18.8% vs. 26.0%; P = .003), an opposite trend was observed among those with HCLs (39.0% vs. 34.0%; P = .26; P int = .005).
The patients with HCLs had higher SYNTAX scores (30.8 vs. 22.4; P < .001) and more complex CAD, so their lack of 10-year mortality benefit with CABG “is somewhat unexpected and warrants further scrutiny,” added Dr. Baber, from the University of Oklahoma Health Sciences Center in Oklahoma City.
Dr. Serruys and Dr. Kawashima agreed that “this study highlights the need for further research on this topic focusing on this specific population with HCLs,” which were 30% of the patients with complex lesions who participated in SYNTAXES.
Consider factors beyond coronary anatomy
The current findings reinforce “the importance of considering not just coronary anatomy, but patient age and other comorbid factors when evaluating mode of revascularization,” said Dr. Baber.
“Coronary calcification is a strong factor in deciding between CABG versus PCI, as multiple studies have shown that CAC increases risk after PCI, even with contemporary safe stent platforms,” he explained in an email.
The current study suggests the adverse prognosis associated with CAC also persists for patients treated with CABG.
Dr. Baber said that, “for patients in whom PCI may not be feasible due to extensive and bulky coronary calcification, it is important to emphasize that the benefits of CABG (versus PCI) may not be as significant or durable.”
“The lack of benefit with CABG,” he added, “is likely due to comorbid factors that tend to increase in prevalence with vascular calcification (older age, peripheral arterial disease, renal impairment, etc).”
This study reinforces “the importance of not just considering coronary complexity, but also additional noncoronary factors that influence long-term prognosis in patients with advanced multivessel CAD,” Dr. Baber stressed.
More aggressive lipid-lowering or antithrombotic therapy may improve the prognosis for such patients, he suggested.
“In general,” Dr. Serruys and Dr. Kawashima similarly noted, “for short-/mid-term outcomes, CABG is preferred to PCI in patients with HCLs because of a higher rate of complete revascularization and less need for repeat revascularization.”
“Our findings at 10 years are in line with the general findings preferring CABG in mid and long term, whereas the benefit of very long-term follow-up might be more complex to capture and comprehend,” they concluded. “Whether HCLs require special consideration when deciding the mode of revascularization beyond their contribution to the SYNTAX score deserves further evaluation.
“Newer PCI technology or CABG methods may become a game-changer in the future,” they speculated.
Worse clinical outcomes
Heavy coronary calcification is associated with worse clinical outcomes after PCI or CABG, but to date, no trial has compared 10-year outcomes after PCI or CABG in patients with complex CAD with versus without HCLs.
To look at this, Dr. Kawashima and colleagues performed a subanalysis of patients in the SYNTAXES study. The original SYNTAX trial had randomized 1,800 patients with complex CAD who were eligible for either PCI or CABG 1:1 to these two treatments, with a 5-year follow-up, and SYNTAXES extended the follow-up to 10 years.
Of the 1,800 patients, 532 (29.6%) had at least one HCL and the rest (70.4%) did not.
The median follow-up in SYNTAXES was 11.2 years overall and 11.9 years in survivors.
At baseline, compared with other patients, those with HCLs were older and had a lower body mass index and higher rates of insulin-treated diabetes, hypertension, previous cerebrovascular disease, peripheral vascular disease, chronic obstructive pulmonary disease, chronic kidney disease, and heart failure.
After adjusting for multiple variables, having a HCL was an independent predictor of greater risk of 10-year mortality (hazard ratio, 1.36; 95% confidence interval, 1.09-1.69; P = .006).
In patients without HCLs, mortality was significantly higher after PCI than CABG (HR, 1.44; 95% CI, 1.14-1.83; P = .003), whereas in those with HCLs, there was no significant difference (HR, 0.85; 95% CI, 0.64-1.13; P = .264).
The location of the HCL did not have any impact on 10-year mortality regardless of the assigned treatment.
Among patients with at least one HCL who underwent CABG, those with at least two HCLs had greater 10-year all-cause mortality than those with one HCL; this difference was not seen among patients with at least one HCL who underwent PCI.
The researchers acknowledge study limitations include that it was a post hoc analysis, so it should be considered hypothesis generating.
In addition, SYNTAX was conducted between 2005 and 2007, when PCI mainly used first-generation paclitaxel drug-eluting stents, so the findings may not be generalizable to current practice.
SYNTAXES was supported by the German Foundation of Heart Research. SYNTAX, during 0- to 5-year follow-up, was funded by Boston Scientific. Dr. Serruys reported receiving personal fees from SMT, Philips/Volcano, Xeltis, Novartis, and Meril Life. Dr. Kawashima reported no relevant financial relationships. Dr. Baber reported receiving honoraria and speaker fees from AstraZeneca, Biotronik, and Amgen.
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