In ten patients with Prinzmetal's variant form of angina the effects of various drugs were assessed: subcutaneous injection of methacholine (10 mg), atropine (0.7 mg), and epinephrine (0.7 mg); intravenous infusion of isoproterenol (20-25 µg/min); and in the three of the above patients who were having recurrent spontaneous attacks at the time of the examination, oral administration of atropine (0.6-1.2 mg), propranolol (30-90 mg), and phenoxybenzamine (10 mg in one patient). Master's triple two-step test and selective coronary arteriography were done on all the patients. In the three patients who were having spontaneous attacks at the time of the examination, the administration of methacholine induced the attacks and that of atropine suppressed the attacks. Epinephrine induced the attacks in two patients and propranolol was without effect in suppressing the attacks. Phenoxybenzamine (in one patient) suppressed the attacks. Neither Master's triple two-step test nor isoproterenol infusion precipitated the attacks, though heart rate increased to more than 110 beats/min and 160 beats/min respectively in all the patients. Coronary arteriograms were normal in seven of the ten patients. It is concluded that enhanced activity of the parasympathetic nervous system, which occurs at rest, is involved in the initiation of the attack by stimulating the sympathetic nerve which in turn probably induces coronary arterial spasm by way of activating alpha (vasoconstrictor) receptors present in the large coronary arteries.

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The long-term outcome of percutaneous coronary intervention (PCI) compared to coronary artery bypass grafting (CABG) for unprotected left main coronary artery disease (ULMCAD) remains to be investigated. We identified 1,005 patients with ULMCAD of 15,939 patients with first coronary revascularization enrolled in the CREDO-Kyoto PCI/CABG Registry Cohort-2. Cumulative 3-year incidence of a composite of death/myocardial infarction (MI)/stroke was significantly higher in the PCI group than in the CABG group (22.7% vs 14.8%, p = 0.0006, log-rank test). However, the adjusted outcome was not different between the PCI and CABG groups (hazard ratio [HR] 1.30, 95% confidence interval [CI] 0.79 to 2.15, p = 0.30). Stratified analysis using the SYNTAX score demonstrated that risk for a composite of death/MI/stroke was not different between the 2 treatment groups in patients with low (<23) and intermediate (23 to 33) SYNTAX scores (adjusted HR 1.70, 95% CI 0.77 to 3.76, p = 0.19; adjusted HR 0.86, 95% CI 0.37 to 1.99, p = 0.72, respectively), whereas in patients with a high SYNTAX score (≥33), it was significantly higher after PCI than after CABG (adjusted HR 2.61, 95% CI 1.32 to 5.16, p = 0.006). In conclusion, risk of PCI for serious adverse events seemed to be comparable to that after CABG in patients with ULMCAD with a low or intermediate SYNTAX score, whereas PCI compared with CABG was associated with a higher risk for serious adverse events in patients with a high SYNTAX score.

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