A 55-year-old male presented with chest pain. He had a history of hypertension and angina, and underwent PCI for proximal LCX in 2023. At that time, an attempt to treat LAD stent ISR CTO lesion failed. Recently, he experienced persistent chest discomfort and visited for coronary work-up. 
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On admission, ECG showed normal sinus rhythm without ST changes or new findings. Echocardiography revealed EF 53% and pre-existing RWMA with thinning in the LAD territory. Vitals were stable. Blood pressure was 118/69 mmHg, and heart rate was 70 beats per minute. The main blood test results showed a CK-MB level of 2.07 ng/ml, Troponin T of 10.10 pg/ml, and NT-proBNP of 72.6 pg/ml. Other blood test results did not reveal any significant findings.
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On coronary angiography performed upon admission, the previously treated LCX lesion from 2023 was patent, and the previously failed CTO lesion showed no significant interval change. As no significant stenosis was noted in the RCA, the LAD CTO lesion was considered the likely cause of symptoms. A second-staged PCI was planned, the angiography was concluded, and a reattempt of the CTO intervention was scheduled after further planning.

In 2023, initial attempts to cross the CTO lesion were made using a microcatheter (Caravel) with Fielder XT-R and XT-A wires. However, the wire repeatedly entered a branch vessel outside the stent in the mid-LAD, failing to cross the main vessel CTO lesion.  After approximately one hour of unsuccessful attempts, the procedure for the CTO lesion was deferred, and only the LCX lesion(CTO) was treated. The patient was followed up in the outpatient clinic but was eventually lost to follow-up. In August 2025, a patient previously lost to follow-up returned with chest discomfort. Follow-up coronary angiography did not reveal a clear culprit lesion, so it was decided to reattempt intervention for the LAD CTO lesion. The prior failure in 2023 was attributed to the wire repeatedly entering a branch vessel outside the stent in the mid-LAD, creating an unintended channel and making it difficult to access the true lumen of the main vessel. This time, a new strategy was planned using a 45-degree angled Supercross microcatheter and a Gaia First wire. The direction of the Supercross was intentionally aimed away from the previously entered branch vessel to guide the wire toward the desired path. With this approach, the Gaia First wire was able to cross the CTO lesion relatively smoothly. The intervention was completed successfully in a short period without complications.
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When performing a repeat intervention on an old, previously failed ISR-CTO lesion, we always strive to try something different from the previous attempt. This may include switching from an antegrade to a retrograde approach, using a different wire, or considering various other strategies. One of the key challenges, as in our case, is the presence of a pre-formed microchannel in the wrong direction, which prevents easy access to the main vessel CTO lesion. In this case, we developed a specific strategy to guide the wire in the desired direction, and the attempt resulted in a successful procedure. We would like to share this experience.