ST-elevation indicates transmural ischemia and corresponds to the distribution of the involved artery.769 A circadian varia- tion is often present; most attacks occur in the early morn- The most prominent coronary risk factor is smoking. Most episodes resolve without complications, but arrhyth- mias, syncope, MI, and sudden death can occur.772 Provocative testing during invasive coronary angiography (eg, using ergonovine, acetylcholine, methylergonovine) is relatively safe, especially when performed in a controlled manner by experienced operators. However, sustained spasm, serious arrhythmias, and even death can also occur very infrequently. Therefore, provocative testing should be avoided in patients with significant left main disease, advanced 3-vessel disease, presence of high-grade obstructive lesions, significant valvular stenosis, significant LV systolic dysfunction, and advanced HF. Nonpharmacological provocative tests, such as cold pressor and hyperventilation, have been used diagnostically; potent vasoconstrictors (eg, acetylcholine) may be useful when non- invasive assessment is uninformative.764 767 Smoking, which exacerbates coronary vasospasm, should be proscribed, and CCBs are first-line therapies642 ; long-acting nitrates are also effective when combined with CCBs.755,758 Statins improve endothelium-dependent vasodilation and can be useful in vaso- Magnesium supplementation and alpha- receptor blockers may be effective and can be added.755,758 7.12. ACS With Angiographically Normal Coronary Arteries: Recommendation Class IIb 1. 