A Mechanism for Stroke Complicating Coronary Thrombus Aspiration.

Coronary thrombus aspiration was developed to remove thrombus, prevent distal embolization, and prepare the vessel for definitive intervention. However, its use is now limited by the risk of stroke. We describe a case where appropriate aspiration technique likely prevented central embolization of a coronary thrombus. (Level of Difficulty: Beginner.).

Aspiration thrombectomy during ST-segment elevation myocardial infarction (STEMI) has been associated with excess risk of stroke (1). We hypothesize that stroke may be caused by incomplete aspiration of embolus through an aspiration catheter, dislodgement as the aspiration catheter is withdrawn from the guide catheter, and subsequent injection from the guide catheter into the general circulation. We report a case where the first 2 steps of this 3-step sequence occurred, and the final step, ejection of a thrombus through the guide catheter, was averted only by careful flushing of the guide and Tuohy connector. We propose strategies to avoid stroke during coronary thrombus aspiration.

Learning Objectives

To review the risk and benefit of thrombus aspiration in the setting of STEMI.

To present appropriate thrombus aspiration technique in order to prevent thrombus embolization into the systemic circulation.

History of Presentation

A 54-year-old woman presented with retrosternal chest pain and electrocardiogram showing inferior STEMI.

Past Medical History

The patient’s medical history included hypertension, diabetes mellitus type 2, and obstructive sleep apnea.

Differential Diagnosis

Thrombotic coronary occlusion, aortic dissection, pericarditis, and takotsubo cardiomyopathy.

Investigation

Electrocardiography showed ST-segment elevation in the inferior leads. Initial troponin T was negative at <0.01 ng/ml.

Management

The patient was treated with aspirin 324 mg, clopidogrel 600 mg, and heparin 100 U/kg. Supplemental heparin was given to maintain the activated clotting time between 250 and 300 s throughout the procedure.

Coronary angiography 3 h after the onset of symptoms showed a dominant right coronary artery (RCA) with a 100% proximal stenosis (Figure 1). Passing a 0.014-inch wire produced distal flow and demonstrated extensive thrombus filling the entire RCA (Figure 2, Video 1). Passes with an Export XT catheter (Medtronic, Dublin, Ireland) yielded several large thrombi. On the third pass of the catheter, blood return through the catheter stopped prematurely, and the aspiration catheter was withdrawn from the guide catheter with constant suction, taking care that the guide catheter was deeply engaged in the ostium of the RCA. A thrombus was visible protruding from the aspiration port of the guide catheter (Figure 3). Residual thrombus persisted in the proximal artery, and now the posterior descending branch was noted to be occluded by thrombus (Figure 4, Video 2). Intravenous double bolus eptifibatide was administered. Additional passes of the aspiration catheter were made including into the posterior descending branch. On one of these passes, blood return again stopped prematurely, and the catheter was withdrawn. The aspiration catheter was removed from the Tuohy connector without visible thrombus, so the Tuohy connector was flushed as follows: we opened the bleedback control seal by pressing down the cap until bleedback expelled any air and then flushed backward through the bleedback control seal with 10 ml of saline. This yielded a large linear thrombus (Figure 5) that adhered to the guidewire. The target lesion was stented with a 3.5- × 30-mm drug-eluting stent. Final angiography showed normal distal flow and no residual thrombus (Figure 6, Video 3). Eptifibatide was continued for 18 h. Electrocardiography immediately post-percutaneous coronary intervention procedure showed resolution of ST-segment elevation. Peak troponin T level was 8.47 ng/ml. The left ventricular function at discharge was grossly normal, but the inferior and posterior segments were inadequately visualized to assess regional wall motion abnormality.

Figure 1

Initial Right Coronary Artery Angiogram Showing Obstructive Thrombus Characterized by Lucency With Contrast on 3 Sides

Figure 2

Right Coronary Artery After Passing Wire and Initial Aspiration With Aspiration Catheter

Online Video 1

Figure 3

Thrombus Obstructed the Aspiration Port of the Aspiration Catheter, With One-Half of the Thrombus Still Protruding

Figure 4

Right Coronary Artery After Aspiration of the Thrombus Depicted in Figure 3

Residual thrombus persists at the proximal lesion. The posterior descending branch is occluded by thrombus.

Online Video 2

Figure 5

Thrombus Being Flushed From the Tuohy Connector

Figure 6

Final Angiography of the Right Coronary Artery After Stenting

Online Video 3

RCA Angiogram With Residual Thrombus After Passing Wire and Initial Aspiration With Aspiration Catheter

RCA After Aspiration of the 3 Short Thrombi Depicted in Figure 3

Final Angiogram of the RCA After Stenting

Discussion

Three randomized trials have studied manual aspiration thrombectomy in STEMI patients (1, 2, 3). Several meta-analyses concluded that thrombus aspiration (TA) was not associated with reductions in mortality but was associated with statistically significant 50% excess in the incidence of stroke. Therefore, recent STEMI guidelines downgraded routine TA in STEMI from a Class IIa recommendation to a Class III recommendation, but retained a Class IIb recommendation for selective TA (4).

Among the randomized trials of TA, excess risk of stroke was found only in the TOTAL (Trial of Routine Aspiration Thrombectomy with PCI versus PCI Alone in Patients with ST elevation myocardial infarction) (1). It has been postulated that stroke associated with TA is technique-dependent, and that the more careful technique in earlier trials prevented an excess of stroke. The proposed mechanism of TA-associated stroke involves a thrombus that could not be fully aspirated through the aspiration catheter dislodging inside the guide catheter, and subsequently being injected through the guide catheter into the systemic circulation. In the case reported here, the second time that the flow of aspirate ended prematurely, we could not find a protruding thrombus. Suspecting it had dislodged in the Tuohy, we flushed the Tuohy, extruding a huge linear thrombus from the back end. Had we injected through the guide without flushing the Tuohy, this thrombus would likely have embolized either into the coronary artery or into the general systemic circulation.

Follow-Up

At 1-month follow-up, the patient was asymptomatic.

Conclusions

When performing aspiration thrombectomy, it is critical to monitor flow through the aspiration syringe; reduced or absent flow may indicate thrombotic obstruction in the aspiration catheter. Special care should be taken to prevent embolization: 1) insert the guide catheter deeply into the artery so that if thrombus dislodges from the aspiration catheter as it is withdrawn, it will not enter the aorta; 2) provide continuous suction to the aspiration catheter as it is withdrawn; 3) aspirate blood from the guide catheter after withdrawal of the aspiration catheter to remove any thrombus that is dislodged during catheter withdrawal; and 4) flush the Tuohy connector backward after aspiration catheter withdrawal. Future studies of TA should specify techniques to be used for the TA procedure.