Safety of provocative tests of coronary artery spasm and prediction of long-term outcome: need for an innovative clinical research strategy

Abstract

Takagi et al ,1 have reported the findings of a nationwide multicentre Japanese registry on the arrhythmic risk of provocative tests of coronary artery spasm (CAS) in all comers with angiographically documented vasospastic angina (VSA). They recruited a total of 1246 patients who, after the test, were followed for a median period of 32 months in order to quantify major acute cardiac events (MACEs). Although largely retrospective and with an incomplete clinical characterization of patients (no information on onset, duration, and severity of symptoms in patients with focal, diffuse, or microvascular constriction), this study has two major practical clinical implications and suggests that continuing to consider only the most common features of the ‘average’ patient with VSA is unlikely to produce relevant additional novel information; thus the time has come to implement novel clinical research strategies. This report proves the following conclusively, in agreement with previous smaller, single-centre studies: (i) In an unselected spectrum of patients with VSA, the global acute arrhythmogenic risk of provocative tests for CAS was quite low, comparable with that observed during spontaneous anginal episodes [with or without pain or electrocardiogam (ECG) changes]; moreover, the risk of life-threatening events was quite small and unpredictable, on the basis of the descriptors tested. (ii) In the broad range of patients studied, the risk of MACEs during a median follow-up of nearly 3 years was also quite low, and the predictive value of available descriptors for MACEs appears poor. Therefore, innovative clinical research strategies must be developed in order to identify: (i) new, more specific, and more accurate combined predictors of life-threatening events, in carefully characterized subgroups of patients, rather than in all comers; and (ii) the various underlying causal mechanisms of spasm and their specific diagnostic and therapeutic targets. The examination of the composition of the 6.8% …