Background Cardiovascular procedural treatments were deferred at scale during the COVID‐19 pandemic, with unclear impact on patients presenting with non–ST‐segment–elevation myocardial infarction (NSTEMI). Methods and Results In a retrospective cohort study of all patients diagnosed with NSTEMI in the US Veterans Affairs Healthcare System from January 1, 2019 to October 30, 2022 (n=67 125), procedural treatments and outcomes were compared between the prepandemic period and 6 unique pandemic phases: (1) acute phase, (2) community spread, (3) first peak, (4) post vaccine, (5) second peak, and (6) recovery. Multivariable regression analysis was performed to assess the association between pandemic phases and 30‐day mortality. NSTEMI volumes dropped significantly with the pandemic onset (62.7% of prepandemic peak) and did not revert to prepandemic levels in subsequent phases, even after vaccine availability. Percutaneous coronary intervention and coronary artery bypass grafting volumes declined proportionally. Compared with the prepandemic period, patients with NSTEMI experienced higher 30‐day mortality during Phases 2 and 3, even after adjustment for COVID‐19‐positive status, demographics, baseline comorbidities, and receipt of procedural treatment (adjusted odds ratio for Phases 2 and 3 combined, 1.26 [95% CI, 1.13–1.43], P <0.01). Patients receiving Veterans Affairs‐paid community care had a higher adjusted risk of 30‐day mortality compared with those at Veterans Affairs hospitals across all 6 pandemic phases. Conclusions Higher mortality after NSTEMI occurred during the initial spread and first peak of the pandemic but resolved before the second, higher peak—suggesting effective adaptation of care delivery but a costly delay to implementation. Investigation into the vulnerabilities of the early pandemic spread are vital to informing future resource‐constrained practices.