In-hospital prognostic relevance of a reduced ischemic threshold. Studies in 357 consecutive patients with acute coronary syndromes.

Abstract

In 357 patients with unstable coronary syndromes, a reduced pacing ischemic threshold (1-mm ST-segment depression at a heart rate < or = 150 beats per minute) was an independent predictor of main in-hospital events (death, myocardial infarction, or coronary surgery), which occurred in 33 percent (65/200) of the patients with a reduced threshold and in 8 percent (13/157) of those with a normal threshold (p < 0.0001). The incidences of death and infarction in patients with a normal (> 150 beats per minute), modestly reduced (140 to 150 beats per minute), or severely reduced (< or = 130 beats per minute) threshold were progressively higher (1 percent and 4 percent; 3 percent and 12 percent; and 7 percent and 18 percent respectively; p < 0.01). Thus, a reduced coronary reserve is associated with a fourfold increase in in-hospital complications; and when the reserve is severely curtailed, there may be a sevenfold increase in mortality.