Читать книгу Practical Cardiovascular Medicine - Elias B. Hanna - Страница 108

In comparison with fibrinolytic therapy, primary PCI is more effective in re-establishing TIMI 3 flow (95%), and thus reduces 30-day mortality by 2% (7% vs. 9%), recurrent MI by 4% (3% vs. 7%), and stroke by 1%.^26–28 However, this superiority of PCI depends on a DTB <120 minutes and PCI-related delay <60 minutes (delay between the expected time of fibrinolytic therapy and the expected time of balloon inflation). In fact, the “90-minute” and “120-minute” cutoffs of DTB have been established in terms of PCI delays beyond which PCI loses its advantage over fibrinolysis (120-min DTB corresponds to equipoise between PCI and fibrinolysis).

DTB is particularly important if the patient presents early, <3 hours after symptom onset, or if the patient is high-risk (anterior MI, tachycardia, SBP <100 mmHg, Killip class ≥II, age ≥65), as those patients derive the greatest benefit from fibrinolytics and are most harmed by reperfusion delays. In CAPTIM, PRAGUE-2, and the modern STREAM trial, fibrinolytic therapy resulted in the same mortality reduction as primary PCI in patients presenting <2–3 hours after symptom onset (granted that rescue PCI is done if needed, and routine early PCI<24 hours is carried in all patients, as in STREAM).^29–31 Conversely, in low-risk patients presenting late, DTB is less important and, in a large MI registry, PCI-related delays of 100 minutes did not negate the survival advantage of primary PCI over fibrinolytic therapy in those patients.³² In fact, the superiority of PCI over fibrinolysis widens as the presentation is more delayed; while the benefit from fibrinolysis strikingly drops beyond 3 hours, PCI has a less pronounced drop in benefit.³³ In two retrospective analyses that only assessed PCI patients, DTB >90–120 minutes did not impair outcomes vs. DTB<120 min in low-risk patients presenting late.^34,35 Yet in all patients, systems should strive for as small a DTB as possible.

In high-risk patients presenting early, any DTB delay, even within the 90-minute window, is associated with increased mortality compared to a shorter DTB (mortality difference of 0.5–1% for every 30 min DTB delay, e.g., between DTB of 30 min and 60 min).³⁶ This is the rationale behind the ESC recommendations, which go beyond DTB <90 min. ESC recommends a STEMI diagnosis-to-wire crossing time <60 min in patients self-presenting to PCI centers and <90 min in patients transported by paramedics or from non-PCI centers. While this is valuable in early presenters with definite STEMI, keep in mind that aggressive reduction of DTB in all comers on a system level has not been consistently associated with improvement of outcomes,^34,35,37,38 particularly in registries comparing the modern DTB era with a previous era of longer DTB. Overzealous reduction of DTB should not preclude proper clinical and ECG assessment and should not lead to a rushed procedure in a patient whose clinical and ECG picture is not definite for STEMI.

Elderly patients (age >75) – In fibrinolytic trials, the benefit from fibrinolytic therapy was much less striking in the elderly than in the young.^10,39 Conversely, primary PCI remains effective in the elderly, with more absolute mortality reduction in the elderly than in young patients. This makes fibrinolytic therapy, whether standalone or combined with PCI, a less attractive alternative to primary PCI in the elderly. Studies of combined fibrinolytic therapy and PCI included very few patients over the age 75.⁴⁰ In the modern STREAM trial of fibrinolysis vs. PCI, the dose of TNK was reduced by 50% in the elderly midway through the trial, which attenuated intracranial hemorrhage without reducing TNK efficacy.41 Hence, ESC guidelines suggest a half-dose of TNK in the elderly ≥ 75 (class IIa).²