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Letter by Sheikh et al Regarding Article, "Invasive Evaluation Of Patients With Angina in the Absence of Obstructive Coronary Artery Disease".

We applaud the authors of “Invasive Evaluation of Patients With Angina in the Absence of Obstructive Coronary Artery Disease,” 1 who demonstrated an occult coronary abnormality in more than three quarters of these patients. Identifying the underlying abnormality is especially important for potentially life-threatening conditions that are amenable to treatment such as coronary artery spasm. Coronary spasm is associated with myocardial infarction, arrhythmias, and sudden death yet is responsive to calcium channel blockers and nitrates. Surprisingly, as stated in the accompanying editorial,2 no patient had inducible spasm on acetylcholine provocation. This observation warrants closer scrutiny, particularly in relation to the acetylcholine provocation method used.

Intracoronary acetylcholine administration is used to assess the presence …