The hyperventilation test as a method for developing successful therapy in Prinzmetal's angina

In 10 cases of Prinzmetal's angina in which episodes of myocardial ischemia were easily and reproducibly induced by hyperventilation, this test was performed 111 times, 41 times under control conditions and 70 times during treatment with one or more of the following drugs: phentolamine, isosorbide dinitrate, propranolol, verapamil, nifedipine and amiodarone. Seventeen of 18 negative tests performed under the influence of a long-acting drug coincided with total remission of the patient's anginal episodes when this drug was administered on a short- or long-term basis. No patient died or sustained infarction during a follow-up period of 10.9 months. A negative test was thus a good indication that the clinical response to the corresponding drug would be favorable. The electrocardiographic changes and chest pain provoked by hyperventilation occurred not when alkalosis was greatest (hydrogen ion [pH] change from 7.42 to 7.58, p less than 0.001), but when pH was approaching normal or control values. The onset of electrocardiographic changes occurred an average of 175 seconds after the end of hyperventilation and, in two cases, the time lag was as much as 480 and 705 seconds, respectively. This raises several questions regarding the true mechanism triggering coronary spasm under such conditions. The hyperventilation test appears to be a useful and safe procedure for selecting the best possible drug for long-term treatment of Prinzmetal's angina as well as for comparing the relative efficacy of different drugs.

Long-term management of sustained, recurrent, symptomatic ventricular tachycardia with amiodarone

Twenty-three patients with sustained, recurrent, symptomatic ventricular tachycardia were treated with oral amiodarone. Initial doses were 600-2000 mg/day and maintenance doses were 200-1200 mg/day. Amiodarone was highly effective in 20 patients (87%), seven of whom had a follow-up of 30 months or longer, including two who were followed for 5 years. Three patients died within the first 45 days, three died suddenly after a follow-up of 33.5 months, and four had a nonarrhythmic death after a follow-up of 25 months. Fifteen patients (65%) had no recurrence during a follow-up of 21.5 months, while five (22%) had isolated recurrences during a follow-up of 32.2 months. The average maintenance dose was 713 mg/day in the 15 patients who did not have recurrences and 375 mg/day in the five patients who had recurrences (p less than 0.001). Both short- and long-term tolerance were excellent and there was not a single case in which treatment had to be discontinued. The main disadvantage of amiodarone was that it took an average of 9.5 days to reach anti-arrhythmic efficacy. The main advantages were prolonged duration of action (recurrences occurred only 15-60 days after the drug was discontinued or the dose lowered, virtual absence of contraindications, doses as high as 2000 mg/day were safe and patient compliance was excellent.