Circadian rhythms and coronary events: implications for therapy

Effect of metoprolol and amlodipine on myocardial total ischaemic burden in patients with stable angina pectoris

OBJECTIVE

A randomized double-blind cross-over study to assess the effect on myocardial total ischaemic burden and the anti-anginal efficacy of the beta-1-blocker metoprolol given as metoprolol CR/Zok versus the calcium channel blocker amlodipine, both given in the recommended and commonly used doses of 100 mg o.d. and 5 mg o.d., respectively.

METHOD

Fifty-two patients with a history of stable exercise-induced angina pectoris and at least six episodes of significant ST-segment depression during 24-h ambulatory electrocardiographic monitoring after 9 days of placebo were included in the study. The patients first completed a 9-day placebo run-in phase with additional administration of a long-acting nitrate during the first 7 days. They then received in a randomized sequence metoprolol CR/Zok and amlodipine each for 4 weeks. During placebo treatment and at the end of each phase of active treatment the patients' clinical progress was assessed and a 24-h ECG monitor performed.

RESULTS

Forty-seven patients completed the two 4-week treatment periods. Five patients withdrew from the study. The number of ischaemic episodes during 24 h was 30.4 at baseline with placebo, which was reduced significantly by both treatments (P<0.005) to 6.8 episodes after metoprolol and 15.8 episodes after amlodipine treatment (P<0.001 for the difference between the treatment groups). Metoprolol and amlodipine reduced the total duration of ischaemic episodes from 86.0 min to 15-1 and 48.3 min with a mean episode duration of 1.1 and 2.6 min, respectively. Twenty patients on metoprolol (42.6%) and four on amlodipine (8.4%) showed no ST-segment depression at the end of treatment. Baseline heart rate of 80 b.p.m. decreased by 11.1 b.p.m. after metoprolol and increased by 4b.p.m. after amlodipine. Anginal attacks were reduced from 14.8 attacks per week at baseline to 2.4 attacks on metoprolol and 4.4 attacks on amlodipine treatment. For all variables the observed changes from baseline were significant after either treatment (P<0.005) with a significantly more pronounced effect in favour of metoprolol (P<0.0001). Ten patients reported nine different adverse events during metoprolol treatment. On amlodipine, 12 patients were affected by 11 different symptoms leading to three treatment withdrawals. On metoprolol one patient withdrew due to adverse events.

CONCLUSION

Both drugs reduce total ischaemic burden by reducing ischaemic episodes and antianginal attacks, with a significantly greater effect from metoprolol 100 mg o.d. as compared to amlodipine 5 mg o.d.

Circadian occurrence of variceal bleeding in patients with liver cirrhosis

Several clinical events have a rhythmicity over the 24 h period. We assessed the presence of periodic rhythm in the occurrence of haematemesis in patients with liver cirrhosis under different daylight regimens, namely during standard time and during daylight savings. Over a 48 month period there were 212 consecutive admissions of 118 cirrhotics with variceal bleeding. Complete data were available for 181 episodes of bleeding: 121 (66.9%) started with haematemesis and 60 (33.1%) started with melaena. One hundred and two (56%) episodes occurred during daylight savings and 79 (44%) occurred during standard time. The cosinor test showed a 24 h biphasic peak for the occurrence of haematemesis (09.45 and 21.45 h). Moreover, a biphasic diurnal asymmetric frequency was also found by multiple component rhythmometry. The time peaks of onset of variceal haemorrhage did not change significantly during standard time and daylight savings. Patients with more than one haematemesis episode significantly bled over the same time interval. The present study confirms that over the 24 h period variceal bleeding in cirrhotic patients occurs with a predictable rhythmicity that does not seem to be under the control of the light-dark cycle. The finding of a chronorisk for variceal haemorrhage addresses specific questions for pathophysiological studies as well as for new treatment strategies.

Evaluation of antihypertensive effects of once-a-day isradipine and fosinopril: a double-blind crossover study by means of ambulatory blood pressure monitoring

We compared the efficacy and tolerability of isradipine (ISR) and fosinopril (FOS) once-a-day administration in 17 outpatients, 9 men and 8 women, aged 35-65 years (mean +/- SD = 58 +/- 10 years), affected by mild to moderate primary systemic hypertension. The patients were given single-blind placebo for 2 weeks and thereafter, in double-blind, randomized, crossover sequence, ISR (5 mg) and FOS (20 mg), both for 4 weeks. At the end of each period, patients underwent 24-h noninvasive blood pressure (BP) monitoring by means of an A&D TM 2420 Monitor Model 7, with readings taken very 10 min during the day (from 7 A.M. to 11 P.M.), and every 20 min during the night (from 11 P.M. to 7 A.M.) Similarly, BP load (BPL) as percentage of systolic and diastolic BP reading > 140 and > 90 mmHg was investigated. Both ISR and FOS induced a highly significant (p < 0.0001) decrease in BP from 158/96 +/- 7/6 mmHg to 133/86 +/- 6/6 and to 132/83 +/- 10/7 mmHg, respectively. Mean BP decreased from 117 +/- 6 mmHg to 102 +/- 6 mmHg (ISR) (p < 0.0001) and to 99 +/- 8 mmHg (FOS) (p < 0.0001). Both ISR and FOS significantly (p < 0.0001) reduced systolic BPL from 78 +/- 16% to 44 +/- 13% and 28 +/- 12%, respectively, and diastolic BPL from 70 +/- 15% to 40 +/- 13% (p < 0.0001) and 35 +/- 13% (p < 0.0001), respectively.(ABSTRACT TRUNCATED AT 250 WORDS)