The addition of thrombectomy to percutaneous coronary intervention didn’t improve cardiac flow or clinical endpoints any more than PCI alone in patients with a subacute ST-elevation myocardial infarction.
Thrombosis aspiration decreased microvascular obstruction less than 1% more than did PCI alone – 2.5% vs. 3% of the left ventricular mass, Dr. Steffan Desch said at the Transcatheter Cardiovascular Therapeutics annual meeting. There were also no significant differences in infarct size, myocardial salvage, or left ventricular ejection fraction, he said at the meeting sponsored by the Cardiovascular Research Foundation.
“Routine manual thrombectomy and aspiration didn’t show any significant reduction in microvascular obstruction on imaging,” said Dr. Desch of University Heart Center, Lübeck, Germany. “This finding was supported by a variety of secondary endpoints, none of them significantly beneficial.”
The study, which was simultaneously published online (JACC Cardiovasc Interv. 2015. doi: 10.1016/j.jcin.2015.09.010), gives the first firm evidence that clot removal is not particularly helpful to patients who present late after symptom onset. With a mean development time of 28 hours, thrombi in this cohort were more mature, with higher fibrin content than the typically soft material seen in patients with acute ST-elevation myocardial infarction (STEMI). When the clot becomes denser and more organized, it is likely less suitable for aspiration, he said.
The cohort comprised 152 patients who presented in a 12- to 48-hour window after onset of symptoms. They were randomized to either standard PCI or to clot aspiration followed by PCI. The primary outcome was the extent of major vessel occlusion on magnetic resonance imaging conducted 1-4 days after the intervention. Secondary outcomes included infarct size, myocardial salvage, and left ventricular volume and ejection fraction.
Patients were a mean of 66 years old, with typical baseline characteristics. Most were men; hypertension was common (about 70%). About half had signs of ongoing ischemia at admission. The door-to-balloon time was 78 minutes in the combination therapy group and 62 minutes in the PCI-only group. Most (62.5%) had a complete occlusion of the culprit vessel.
In addition to providing no benefit in microvascular occlusion, aspiration did not significantly improve TIMI flow grade above that achieved with PCI only. After the intervention, 78% of those in the thrombectomy group and 69% of those in the PCI group achieved a TIMI flow grade 3. Nor was there a significant difference in myocardial blush grade (70% vs. 65%). When troponin T values were used to assess enzymatic infarct size, they were similar in both groups at 24 and 48 hours.
Clinical outcomes were similar as well. All-cause mortality was 3% in the aspiration group and 5% in the PCI-only group; cardiovascular death occurred in 3% and 4%, respectively. There were no reinfarctions and no stent thromboses. One stroke occurred in a patient who underwent PCI alone.
Dr. Desch noted in the published article that the study took all comers, rather than selecting for specific patient characteristics. Therefore, he said “it is possible that thrombus aspiration might only be advantageous in specific subsets of patients such as those with large thrombus burden, total occlusion or reduced flow.”
The study was funded by a research grant from Medtronic. Dr. Desch reported grant/research support from Medtronic.