C ardiac resynchronization therapy (CRT) with biventricular pacing has emerged as a new approach for treating patients with heart failure and significant ventricular conduction delay and/or dyssynchrony. 1-3 CRT improves left ventricular systolic and diastolic function 4 and clinical status 5 and reduces functional mitral regurgitation (MR). 6 Whether CRT significantly affects exercise-induced changes in MR has never been investigated. This study examined the effects of CRT on MR and assessed the determinants of exercise-induced changes in MR under biventricular pacing.• • • This prospective study included 27 consecutive patients with heart failure who were clinically helped by biventricular pacing. Before CRT implantation, all were in New York Heart Association class III and had left ventricular ejection fractions Յ35%, functional MR, were in sinus rhythm, had QRS duration Ն140 ms, and had interventricular delay (the time interval between aortic and pulmonary valve opening) Ն50 ms. All patients underwent quantitative exercise Doppler echocardiography with and without active CRT. The causes of heart failure were idiopathic dilated cardiomyopathy in 9 patients and ischemic heart disease in 18. The protocol was approved by the human ethical committee of our university hospital, and all patients gave informed consent.A symptom-limited graded bicycle exercise test was performed in a semisupine position on a tilting exercise table. After an initial workload of 25 W maintained for 2 minutes, the workload was increased every 2 minutes by 25 W. Blood pressure and 12-lead electrocardiograms were recorded every 2 minutes. Two-dimensional and Doppler echocardiographic recordings were available throughout the test.Baseline and exercise echocardiographic studies were performed 45 Ϯ 16 days after implantation of the CRT system using the phased-array Acuson Sequoia (Siemens AG, Munich, Germany) or VIVID 7 (GE Healthcare, Little Chalfont, United Kingdom) imaging device. In 17 patients, after data acquisition during active CRT (CRT on), pacing was interrupted during 30 minutes before data acquisition during intrinsic conduction (CRT off). In the other 10 patients, data were first acquired with CRT off. All echocardiographic and Doppler recordings were obtained in digital format and stored on optical discs for off-line analysis. For each measurement, Ն3 cardiac cycles were averaged. The quantitation of MR was performed by the quantitative Doppler method using mitral and aortic stroke volumes and the proximal isovelocity surface area method, as previously described. 7,8 The results of these 2 methods were averaged, allowing the calculation of regurgitant volume and the effective regurgitant orifice (ERO). Left ventricular end-diastolic and end-systolic volumes and ejection fractions were measured by the bi-apical Simpson disk method. The left ventricular dP/dt was estimated from the steepest increasing segment of the continuous-

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SUMMARYNinety-five patients with angina at rest were observed in the coronary care unit. Eighty-one per cent presented concomitantly or had previously presented some other manifestations of coronary artery disease. These patients were divided into two subgroups. In subgroup 1 (40 patients), episodes of non-exertional angina were associated with a pattern of hyperacute subepicardial injury and, frequently, with ventricular arrhythmias. In subgroup 2 (55 patients), the episodes of angina at rest were attended by horizontal ST depression, isolated T wave inversion, or trivial ST-T changes. Coronary angiographic findings were similar in both subgroups.Symptoms regressed in only 9% of patients in subgroup 1 while they were receiving beta-receptor antagonists, whereas amiodarone alone or amiodarone with nifedipine was successful in 58%. Of these patients, 25% developed a myocardial infarction shortly after admission.In subgroup 2 patients, beta-blockers were successful in 61%. Amiodarone isolated or associated with nifedipine was successful in 55% of the patients in whom it was tried. Only 5% of patients in this subgroup developed a myocardial infarction during their hospital stay.It is concluded that: (1) observation of the electrocardiogram during spontaneous angina in patients with known atherosclerotic coronary heart disease may be of prognostic significance and may influence therapeutic decision. (2) Amiodarone by virtue of its anginal and antiarrhythmic properties may be particularly useful in the treatment of non-exertional angina.It has long been recognised that angina pectoris can occur spontaneously at rest and that different pathogenetic mechanisms may be involved in the production of this type of myocardial ischaemia.Recent studies have identified coronary vasospasm as one of the possible causes of the hyperacute attacks of ischaemia which occur at rest. 1-7 This new concept raises some questions regarding the therapeutic approach for patients with non-exertional angina.5Recently, in our coronary care unit we have observed 95 patients with angina at rest. The present report is concerned with the clinical features and results of treatment in these cases.

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In a group of 45 patients treated with Medtronic 7000 and 7100 pulse generators for sick sinus syndrome or second or third degree atrioventricular block, an atrial synchronous mode of pacing was programmed in 34 cases and spontaneously occurring artificial circus movement tachycardias (ACMTs) were observed in nine. An analysis of conditions of occurrence, triggering mechanisms and patterns of ACMT, is presented. Various modalities of prevention are discussed. They resulted in suppression of ACMT in five patients and decrease of incidence in a sixth; the three remaining subjects were managed by definitive reprogramming in the DVI mode. Our conclusion is that correct prevention of ACMT requires the use of dual chamber pulse generators with programmable atrial refractory periods. For patients in whom a unit has already been implanted, careful observation of the triggering mechanism and pattern of ACMT may help in determining the most suitable way to prevent and suppress the arrhythmia.