Background: The appearance of remote ST segment depression (RSTD) on an electrocardiogram (ECG) is associated with more extensive infarction and a worse clinical outcome than when RSTD is absent.
Objective: To determine whether RSTD predicts coronary anatomy during acute coronary occlusion. It was hypothesized that RSTD is associated with the occlusion of a proximal lesion, an extensive artery and an artery without distal collateralization.
Patients and methods: In 113 consecutive patients with single vessel disease undergoing percutaneous transluminal coronary angioplasty (PTCA), 12-lead ECGs (recorded at baseline and during balloon inflation) and angiographical data were analyzed independently. Patients with ST segment elevation in the primary territory and RSTD (greater than 1 mm ST depression at 80 ms after the J point) (group A) were compared with patients without RSTD (group B). Proximal lesions were defined as lesions located in the segments proximal to the acute marginal branch, first diagonal artery or first obtuse marginal branch. An extensive right coronary artery (RCA) was one that supplied the posterolateral wall; an extensive left anterior descending (LAD) artery was one that supplied the inferoapical wall; and an extensive circumflex artery was one that supplied the posterior descending artery.
Results: Fifty-four patients (48%) had PTCA of the proximal vessels, 43 patients (38%) had extensive target vessels and 11 patients (9.7%) had collaterals. Target vessels included 33% in RCA, 44% in LAD artery and 23% in circumflex artery. Forty-five patients (40%) developed RSTD during balloon inflation (group A). Patients in group A were more likely to have extensive vessels on the angiogram than those in group B (group A 49%, group B 31%; P=0.05). None of the patients in group A had collaterals to the culprit artery, while 16% of patients in group B did (P=0.003). The two groups were not significantly different with respect to the number of proximal lesions (group A 58%, group B 42%; P=0.08). Analysis performed according to the target artery revealed that RSTD was associated with occlusion of an extensive RCA during RCA occlusion (extensive RCA in group A 100%, group B 57%; P=0.006). For the LAD artery, RSTD was associated with proximal lesions (group A 74%, group B 41%; P=0.02) and absence of collaterals (group A 100%, group B 74%; P=0.01).
Conclusions: During acute coronary occlusion, the presence of RSTD on 12-lead ECG was specific for the absence of collaterals. The presence of RSTD during RCA occlusion was strongly associated with an extensive RCA, suggestive of posterolateral wall ischemia. During LAD artery occlusion, the presence of RSTD was associated with proximal occlusion, which resulted in ischemia of the LAD artery and the major diagonal artery territories.