Background: The randomized OCTOBER trial finds the use of invasive imaging by optical coherence tomography (OCT), lesion preparation via scoring balloon and provisional T-stenting as the default PCI strategy in bifurcation lesions including left main (LM) disease to improve outcomes. Clinical results of this approach in routine practice are not yet known. Aim / Objective: The study investigated safety and efficacy of the OCTOBER study approach in routine, elective unprotected LM PCI. Methods and Results: From 2015 the group adopted a treatment strategy for LM disease favoring OCT-guided PCI preferentially performed with a one-stent technique including lesion preparation by a nitinol based scoring balloon. Over a 5.5-year period, elective, unprotected LM PCI was performed in 123 consecutive patients. 90 (73.2%), patients received lesion preparation by scoring balloon. OCT imaging was employed in 34 (27.6%), 106 (86.2%), patients were treated with a provisional T-stenting strategy. Clinical endpoints were available up to 6 years with a mean follow-up of 2.3 years. Major adverse cardiovascular and cerebrovascular events (MACCE), were observed in 26.8% patients. Target lesion revascularisation (TLR), and target vessel revascularisation (TVR), rates were observed at 4.1% and 5.7%, respectively. In this elderly population with a mean age of 72.9 years, overall mortality was 12.2% with 5.7% classified as cardiovascular mortality. Conclusion: This registry finds modified unprotected LM PCI incorporating OCT guiding, lesion preparation and default provisional T-stenting to be associated with low rates of myocardial infarct and CV mortality over a mean follow-up of 2.3 years until a first clinical endpoint occurred.