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Figure 1 Values of ST-segment shifts on the intracoronary electrocardiogram (IC-ECG) and of cardiac pain severity at the end of the first and second balloon inflations in the two groups of patients. In naloxone-treated patients, ST-segment changes and cardiac pain severity at the end of the second balloon inflation were similar to those at the end of the first inflation. Conversely, in placebo-treated patients, ST-segment changes and cardiac pain severity at the end of the second balloon inflation were significantly less than those at the end of the first inflation.