Platelet aggregability in vivo is attenuated by verapamil but not by metoprolol in patients with stable angina pectoris

Potential Protective Role of Blood Pressure-Lowering Drugs on the Balance between Hemostasis and Fibrinolysis in Hypertensive Patients at Rest and During Exercise

In patients with hypertension, the triad represented by endothelial dysfunction, platelet hyperactivity, and altered fibrinolytic function disturbs the equilibrium between hemostasis and fibrinolysis and translates into a hypercoagulable state, which underlies the risk of thrombotic complications. This article reviews the scientific evidence regarding some biological effects of antihypertensive drugs, which can protect patients from the adverse consequences of hypertensive disease, improving endothelial function, enhancing antioxidant activity, and restoring equilibrium between hemostatic and fibrinolytic factors. These protective effects appear not to be mediated through blood pressure reduction and are not shared by all molecules of the same pharmacological class.

Approach to the Assessment of Platelet Function: Comparison between Optical-based Platelet-rich Plasma and Impedance-based Whole Blood Platelet Aggregation Methods

Platelet aggregation studies play an important role in the assessment of hereditary and acquired platelet function defects. The first aggregation test introduced into laboratory practice used platelet-rich plasma (PRP) where aggregation was detected by an optical method. The assessment of platelet function using whole blood (WB) aggregation by an impedance method followed up nearly 20 years later. The WB impedance aggregation assay appears to be superior to the optical method because it 1) evaluates platelets in a physiologic milieu in the presence of red and white blood cells, which are known to modulate platelet function; 2) is faster; 3) has higher sensitivity; and 4) does not require centrifugation, thus avoiding injury to platelets and loss of giant thrombocytes. These two assays were compared. Clearly, the WB impedance aggregation methodology has many advantages over the optical PRP assay for the assessment of the hyperactive platelet syndrome and the effects of anti-platelet drugs.

Proton pump inhibitors are associated with lower gastrointestinal tract bleeding in low-dose aspirin users with ischaemic heart disease

BACKGROUND

Impact of acid suppressants on lower gastrointestinal bleeding remains unclear in low-dose aspirin users; we aimed to investigate this relationship.

METHODS

Retrospective cohort study of low-dose aspirin users who underwent coronary angiography for ischaemic heart disease in our institution between October 2005 and December 2006; patients were evaluated for upper or lower gastrointestinal bleedings within 3 years post-angiography.

RESULTS

538 patients were enrolled (males, 74.4%; mean age 67.4±10.6 years). Risk for upper gastrointestinal bleeding decreased with concomitant use of statins (HR, 0.37; 95% CI, 0.15-0.89), calcium channel blockers (HR, 0.29; 95% CI, 0.10-0.85), and histamine-2 receptor antagonists (HR, 0.26; 95% CI, 0.08-0.89). Concomitant use of proton pump inhibitors tended to decrease risk of upper gastrointestinal bleeding (HR, 0.27; 95% CI, 0.06-1.18). Risk for lower gastrointestinal bleeding increased with both concomitant use of warfarin (HR, 15.68; 95% CI, 4.43-55.53) and proton pump inhibitors (HR, 6.55; 95% CI, 2.01-21.32), but not with histamine-2 receptor antagonists. Hyperuricemia lowered risk for lower gastrointestinal bleeding (HR, 0.12; 95% CI, 0.02-0.88).

CONCLUSIONS

In low-dose aspirin users, concomitant use of proton pump inhibitors increased lower gastrointestinal bleeding risk, independent from effects on upper gastrointestinal bleeding.

Systematic review with meta-analysis: the association between the use of calcium channel blockers and gastrointestinal bleeding

BACKGROUND

Due to their potential anti-platelet effect, it is suggested that calcium channel blockers (CCBs) are associated with gastrointestinal bleeding (GIB). However, results from previous studies are conflicting.

AIM

To conduct a systematic review and meta-analysis of randomised controlled trials (RCTs) and observational studies to clarify the association between CCBs and GIB.

METHODS

We conducted a systematic search of PubMed, EMBASE, Cochrane library and Trial Register databases up to January 2015. Studies that evaluated exposure to CCBs reporting GIB outcomes were included in the meta-analysis. The inverse variance method with random effects model was used to calculate the pooled estimates.

RESULTS

Seventeen studies (four RCTs, eleven case-control and two cohort studies) were included in the meta-analysis. The summary risk ratio (RR) for GIB was 1.17 (95% CI 1.01-1.36) for CCB users vs. non-users. Subgroup analysis showed that CCB use was associated with a moderately higher risk of lower GIB (RR = 1.83, 95% CI 1.17-2.84) but not upper GIB. However, data from four RCTs did not support association between CCBs and GIB (RR = 0.93, 95% CI 0.82-1.05). Subgroup analyses further showed that the increased risk of GIB among CCB users was only observed in studies that failed to adjust for prior history of GIB (RR = 1.67, 95% CI 1.34-2.08) or use of anti-ulcer drugs (RR = 1.40, 95% CI 1.19-1.65).

CONCLUSION

Our meta-analysis showed a marginal association between calcium channel blocker use and the risk of gastrointestinal bleeding. This association is of dubious clinical significance, as the effects of different comparators or adjustment for confounding factors render this association nonsignificant.

Risk of hospitalized gastrointestinal bleeding in persons randomized to diuretic, ACE-inhibitor, or calcium-channel blocker in ALLHAT

Calcium channel blockers (CCBs) are an important class of medication useful in the treatment of hypertension. Several observational studies have suggested an association between CCB therapy and gastrointestinal (GI) hemorrhage. Using administrative databases, the authors re-examined in a post-hoc analysis whether the Antihypertensive and Lipid-Lowering Treatment to Prevent Heart Attack Trial (ALLHAT) participants randomized to the CCB amlodipine had a greater risk of hospitalized GI bleeding (a prespecified outcome) compared with those randomized to the diuretic chlorthalidone or the angiotensin-converting enzyme inhibitor lisinopril. Participants randomized to chlorthalidone did not have a reduced risk for GI bleeding hospitalizations compared with participants randomized to amlodipine (hazard ratio [HR], 1.09; 95% confidence interval [CI], 0.92-1.28). Those randomized to lisinopril were at increased risk of GI bleeding compared with those randomized to chlorthalidone (HR, 1.16; 95% CI, 1.00-1.36). In a post-hoc comparison, participants assigned to lisinopril therapy had a higher risk of hospitalized GI hemorrhage (HR, 1.27; 95% CI, 1.06-1.51) vs those assigned to amlodipine. In-study use of atenolol prior to first GI hemorrhage was related to a lower incidence of GI bleeding (HR, 0.69; 95% CI, 0.57-0.83). Hypertensive patients on amlodipine do not have an increased risk of GI bleeding hospitalizations compared with those taking either chlorthalidone or lisinopril.

Antiplatelet effects of Cyperus rotundus and its component (+)-nootkatone

ETHNOPHARMACOLOGICAL RELEVANCE

Cyperus rotundus, a well-known oriental traditional medicine, has been reported to exhibit wide spectrum activity in biological systems including the circulatory system, however, little information is available on its antiplatelet activity. This study was undertaken to investigate the antiplatelet effects of Cyperus rotundus EtOH extract (CRE) and its constituent compounds.

MATERIALS AND METHODS

The antiplatelet activities of CRE and its eight constituent compounds were evaluated by examining their effects on rat platelet aggregations in vitro and ex vivo, and on mice tail bleeding times.

RESULTS

During the in vitro platelet aggregation study, CRE showed significant and concentration-dependent inhibitory effects on collagen-, thrombin-, and/or AA-induced platelet aggregation. Of its eight components, (+)-nootkatone was found to have the most potent inhibitory effect on collagen-, thrombin-, and AA-induced platelet aggregation. In addition, CRE- and (+)-nootkatone-treated mice exhibited significantly prolonged bleeding times. Furthermore, (+)-nootkatone had a significant inhibitory effect on rat platelet aggregation ex vivo.

CONCLUSIONS

This study demonstrates the antiplatelet effects of CRE and its active component (+)-nootkatone, and suggests that these agents might be of therapeutic benefit for the prevention of platelet-associated cardiovascular diseases.

Prothrombotic responses to exercise are little influenced by clopidogrel treatment

AIMS

Adenosine diphosphate (ADP) is involved in shear-induced platelet activation, which may be important for platelet responses to stress. We therefore tested the hypothesis that ADP receptor antagonism by clopidogrel treatment would attenuate exercise-induced platelet activation.

METHODS AND RESULTS

Fifteen healthy volunteers performed exhaustive exercise without and with clopidogrel pretreatment (75 mg/day; 7 days) in a randomised crossover study. Filtragometry readings (reflecting platelet aggregability in vivo) and 11-dehydro-thromboxane B(2) (TxM) in plasma were determined before and after exercise. Platelet and leukocyte activity, platelet-platelet (PPA), and platelet-leukocyte aggregates (PLAs) in vivo and their responsiveness to agonist stimulation in vitro were assessed by flow cytometry. Clopidogrel treatment inhibited ADP-induced platelet P-selectin expression by 72% (54-85%). Exercise increased platelet aggregation (filtragometry and PPAs), elevated plasma TxM, increased single platelet P-selectin expression, elevated circulating PLAs, and enhanced ADP and thrombin-stimulated P-selectin expression. Clopidogrel prolonged filtragometry readings and attenuated agonist stimulated P-selectin expression at rest, but did not influence TxM in plasma or urine or attenuate platelet or leukocyte responses to exercise. Clopidogrel treatment did not influence plasma CD40L (ligand) at rest or after exercise.

CONCLUSION

Clopidogrel treatment attenuates platelet activity in vivo at rest, but exercise counteracts the platelet stabilizing effects of clopidogrel. The hypothesis that ADP is involved in stress-induced platelet activation was not supported.

Prognostic implications of autonomic function assessed by analyses of catecholamines and heart rate variability in stable angina pectoris

OBJECTIVE

To assess the prognostic impact of autonomic activity, as reflected by catecholamines and heart rate variability (HRV), in patients with stable angina pectoris.

DESIGN

Double blind, randomised treatment with metoprolol or verapamil. 24 hour ambulatory ECG, used for frequency domain analyses of HRV, and symptom limited exercise tests at baseline and after one month of treatment. Catecholamine concentrations were measured in plasma (rest and exercise) and urine.

SETTING

Single centre at a university hospital.

PATIENTS

641 patients (449 men) with stable angina pectoris.

MAIN OUTCOME MEASURES

Cardiovascular (CV) death, non-fatal myocardial infarction (MI).

RESULTS

During follow up (median 40 months) there were 27 CV deaths and 26 MIs. Patients who died of CV causes had lower total power and high (HF), low (LF), and very low (VLF) frequency components of HRV. HRV was not altered in patients who suffered non-fatal MI. Catecholamines did not differ between patients with and those without events. Metoprolol increased HRV. Verapamil decreased noradrenaline (norepinephrine) excretion. Multivariate Cox analyses showed that total power, HF, LF, and VLF independently predicted CV death (also non-sudden death) but not MI. LF:HF ratios and catecholamines were not related to prognosis. Treatment effects on HRV did not influence prognosis.

CONCLUSIONS

Low HRV predicted CV death but not non-fatal MI. Neither the LF:HF ratio nor catecholamines carried any prognostic information. Metoprolol and verapamil influenced LF, HF, and catecholamines differently but treatment effects were not related to prognosis.

Blood hemostasis in exercise and training

Formation of the blood clot is a slow but normal physiological process occurring as a result of the activation of blood coagulation pathways. Nature's guard against unwanted blood clots is the fibrinolytic enzyme system. In healthy people, there is a delicate dynamic balance between blood clot formation and blood clot dissolution. Available evidence suggests that exercise and physical training evoke multiple effects on blood hemostasis in normal healthy subjects and in patients. A single bout of exercise is usually associated with a transient increase in blood coagulation as evidenced by a shortening of activated partial thromboplastin time (APTT) and increased Factor VIII (FVIII). The rise in FVIII is intensity dependent and continues into recovery. The effects of acute exercise on plasma fibrinogen have yielded conflicting results. Thus, the issue of whether exercise-induced blood hypercoagulability in vitro mirrors an in vivo thrombin generation and fibrin formation remains disputable. Exercise-induced enhancement of fibrinolysis has been repeatedly demonstrated using a wide range of exercise protocols incorporating various exercise intensities and durations. Moderate exercise appears to enhance blood fibrinolytic activity without a concomitant activation of blood coagulation mechanisms, whereas, very heavy exercise induces simultaneous activation of blood fibrinolysis and coagulation. The increase in fibrinolysis is due to a rise in tissue-type plasminogen activator (tPA) and decrease in plasminogen activator inhibitor (PAI). The mechanism of exercise-induced hyperfibrinolysis is poorly understood, and the physiological utility of such activation remains unresolved. Strenuous exercise elicits a transient increase in platelet count, but there are conflicting results concerning the effect of exercise on platelet aggregation and activation. Few comprehensive studies exist concerning the influence of exercise training on blood hemostasis, making future investigation necessary to identify whether there are favorable effects of exercise training on blood coagulation, fibrinolysis, and platelet functions.

Inflammatory and hemostatic markers in relation to cardiovascular prognosis in patients with stable angina pectoris. Results from the APSIS study. The Angina Prognosis Study in Stockholm

Increased inflammatory activity and platelet activation have been associated with an increased risk of cardiovascular (CV) events in epidemiological studies, but their prognostic importance in patients with stable angina pectoris is less well established. The Angina Prognosis Study in Stockholm (APSIS), comprised 809 patients (2766 patient years) with stable angina pectoris on double-blind treatment with verapamil or metoprolol. Plasma levels of fibrinogen and orosomucoid (an acute phase reactant), white blood cell counts (WBC), platelet counts and the urinary excretion of beta-thromboglobulin (reflecting platelet secretion), were related to the risk of CV death (n=36), non-fatal myocardial infarction (MI) (n=30) or revascularization (n=99) in a subgroup of 782 patients. Verapamil and metoprolol had only minor effects on the inflammatory variables. In multivariate Cox regression analyses (adjusted for previous MI, hypertension, diabetes mellitus and smoking), fibrinogen and WBC were independent predictors of CV death or non-fatal MI, as well as the risk of revascularization. Orosomucoid did not carry any independent information. Platelet counts and urinary beta-thromboglobulin were not significantly related to CV prognosis. The treatment given did not significantly influence the prognostic impact of either fibrinogen or WBC. Fibrinogen and WBC were independent predictors of CV death or non-fatal MI as well as disease progression leading to revascularization in patients with stable angina pectoris. As fibrinogen is also an acute-phase reactant, the present findings indicate that inflammatory activity is involved in disease progression in stable angina pectoris.

Antiplatelet effect of amlodipine: a possible mechanism through a nitric oxide-mediated process

The effect of amlodipine, a novel calcium channel blocker of the dihydropyridine type, on rabbit platelet aggregation, and the possible antiaggregatory mechanisms of amlodipine, especially on the nitric oxide (NO) guanosine 3',5'-cyclic monophosphate (cyclic GMP)-mediated pathway, were investigated. Other effects of amlodipine on thromboxane B2 (TXB2) formation in platelets also were examined. Amlodipine concentration-dependently inhibited rabbit platelet aggregation induced by collagen (10 microg/mL) or thrombin (0.1 U/mL) with an IC50 range of 32-69 microM. Along with this inhibition, our results also demonstrated that in the presence of L-arginine (100 IM), amlodipine (50 microM) increased nitric oxide synthetase (NOS) activity (from the resting activity of 2.05+/-0.36 to 7.11+/-0.95 pmol/mg protein/min) and NO release (by 80%), accompanied by an elevation of the cyclic GMP level (from the resting platelet level of 1.27+/-0.12 to 6.21+/-0.55 pmol/10(9) platelets) induced by collagen (10 microg/mL). However, the antiaggregatory effect of amlodipine (50 microM) could be attenuated significantly by oxyhemoglobin (5 microM), a NO scavenger, or N(G)-nitro-L-arginine methyl ester (100 microM), a specific NOS inhibitor. In addition, the TXB2 production in platelets induced by collagen or thrombin was concentration-dependently inhibited by amlodipine. Therefore, we propose that the antiaggregatory mechanisms of amlodipine might be mediated, in part, by a NO-cyclic GMP process accompanied by the inhibition of TXB2 formation in platelets.

Effect of amlodipine on exercise-induced platelet activation in patients affected by chronic stable angina

BACKGROUND

Literature concerning exercise-induced platelet activation in chronic stable angina is somewhat confusing. The reason lies in the type of exercise as well as in methodological problems. A powerful, recently introduced procedure to detect platelet activation is flow cytometry. Platelet response to activating factors is mediated by calcium uptake; however, calcium antagonist effect on platelet activity is still unclear.

HYPOTHESIS

The study was undertaken to investigate exercise-induced platelet activation before and after treatment with amlodipine in chronic stable angina.

METHODS

Twenty patients with chronic stable angina were entered into the study. Each subject underwent a symptom-limited cycloergometer stress test following a washout period of 2 weeks. Blood samples were collected before and immediately after exercise. All subjects were then randomized into two groups of 10 patients each, with Group 1 and Group 2 taking amlodipine 10 mg/day, and placebo for 4 weeks, respectively. They subsequently underwent a second exercise stress test, and blood samples were obtained before and immediately after exercise. Flow-cytometric evaluation of platelet activity was performed in order to recognize GMP-140 expression on platelet membrane.

RESULTS

Strenuous exercise induced a significant increase in platelet activation in all subjects prior to therapy. No significant differences were observed in platelet activity at rest between Groups 1 and 2, whereas a significant decrease in exercise-induced platelet activation was demonstrated in Group 1 compared with Group 2.

CONCLUSION

Our data provide evidence of the favorable effect of amlodipine on exercise-induced platelet activation in patients affected by chronic stable angina.

Effects of a novel calcium antagonist, benidipine hydrochloride, on platelet responsiveness to mental stress in patients with essential hypertension

The effects of a novel calcium antagonist, benidipine hydrochloride, on responses of platelets to mental stress were evaluated in nine patients with essential hypertension. Before and 12 weeks after the monotherapy with benidipine (2-4 mg/day), platelet aggregability and plasma beta-thromboglobulin were determined during rest and after a 10-min arithmetic stress. Before the treatment, arithmetic stress significantly increased platelet aggregability in response to adenosine diphosphate (ADP) and plasma beta-thromboglobulin level. Blood pressure, pulse rate, and plasma catecholamines also increased during arithmetic stress. The treatment with benidipine did not affect resting values of platelet functions, but attenuated significantly stress-induced alterations in primary aggregation to 1.0 microM ADP (34 +/- 4% to 40 +/- 3% before treatment vs. 32 +/- 2% to 34 +/- 3% after benidipine), ADP threshold for biphasic aggregation (2.2 +/- 0.4 to 1.8 +/- 0.3 microM before treatment vs. 2.2 +/- 0.3 to 2.2 +/- 0.4 microM after benidipine) and plasma beta-thromboglobulin level (74 +/- 16 to 104 +/- 15 ng/ml before treatment vs. 60 +/- 10 to 52 +/- 8 ng/ml after benidipine; p < 0.05 for Stress x Treatment interactions in all values). The pretreatment elevations in blood pressure and sympathetic activity with stress were not modified by benidipine treatment. In conclusion, the monotherapy with benidipine did not affect platelet function during the resting condition, but significantly suppressed the platelet activation induced by arithmetic stress in patients with essential hypertension.

Inhibition of platelet activity in vivo by amlodipine alone and combined with aspirin

Platelets are known to contribute to the initiation and progression of coronary artery narrowing by atherosclerotic plaques. Platelets also initiate periodic occlusive coronary arterial thrombosis that leads to unstable angina and myocardial infarction. Aspirin is the most widely used platelet inhibitor. However, if blood levels of epinephrine are elevated, some of the platelet inhibition produced by aspirin is diminished. Amlodipine, a second generation dihydropyridine calcium channel blocker, was studied in a widely used dog model of experimental coronary artery thrombosis. Amlodipine 1 mg/kg alone or amlodipine 0.4 mg/kg with 5 mg/kg of aspirin I.V. completely abolished the experimental coronary thrombosis and prevented the exacerbation of coronary thrombosis by epinephrine 0.2 microg/kg/min. This protective effect did not appear until 60 minutes after the amlodipine was given, suggesting a delayed onset of action. Long-acting dihydropyridine calcium channel blockers are used in patients with hypertension, angina, and coronary artery disease. They also may offer the patient some protection against fatal or nonfatal myocardial infarction via their platelet-inhibiting effects.

Treatment with verapamil and trandolapril in patients with congestive heart failure and angina pectoris or myocardial infarction. The DAVIT Study Group. Danish Verapamil Infarction Trial

In a double-blind, randomized trial in a consecutive group of postinfarct patients in treatment with diuretic agents for congestive heart failure, the 3 month rate of cardiac events (i.e., death, repeat infarction, unstable angina pectoris, or repeat admission because of heart failure) was 14% in patients treated with verapamil and trandolapril and 35% in patients treated with trandolapril (p = 0.01). In another study of patients with angina pectoris and left ventricular ejection fraction less than 40%, trandolapril plus verapamil improved exercise duration and left ventricular ejection fraction. These findings indicate that combined treatment with verapamil and trandolapril may be beneficial in patients with congestive heart failure.

Treatment with verapamil and trandolapril in patients with congestive heart failure and myocardial infarction. The Danish Verapamil Infarction Trial (DAVIT Study Group)

EFFECTS OF VERAPAMIL AND TRANDOLAPRIL: Progression of heart failure, sudden death and death from re-infarction are the major cause of the increased mortality in postinfarct patients with congestive heart failure. Angiotensin converting enzyme (ACE) inhibitors such as trandolapril can prevent the progression of heart failure and thus improve survival. The calcium antagonist verapamil has been shown to prevent sudden death and re-infarction in postinfarct patients without congestive heart failure.

HYPOTHESIS

The Danish Verapamil Infarction Trial (DAVIT) study group hypothesized the combined treatment with trandolapril and verapamil might prevent cardiac events in postinfarct patients with coronary heart disease. The first double-blind randomized trial included 100 patients and supported this hypothesis, as the cardiac event rate was significantly lower after 3 months in patients treated with the combination than in those treated with trandolapril alone (14 versus 35%, respectively; P = 0.01, hazard ratio 0.35, 95% confidence interval 0.15-0.85).

Different effects of calcium antagonists, nitrates, and beta-blockers on platelet function. Possible importance for the treatment of unstable angina

BACKGROUND

The three major classes of antianginal drug all inhibit platelet aggregation at high concentrations in vitro, but detecting clinically relevant effects has proved to be more difficult. We used whole-blood flow cytometry, a sensitive method that allows direct measurement of activation antigens on the surface of individual platelets in whole unfixed blood, to evaluate the effect of representative antianginal drugs on platelet function in vivo in healthy volunteers.

METHODS AND RESULTS

The effects of glyceryl trinitrate (GTN), amlodipine, and atenolol were studied in nine normal volunteers. Fibrinogen binding to activated GP IIb/IIIa and expression of P-selectin, GP Ib, and GP IIb/IIIa on the platelet surface were measured. In addition, fibrinogen binding and P-selectin expression were measured in response to ex vivo stimulation with the agonists ADP and thrombin. The three drugs had very different effects on platelets. GTN inhibited platelet fibrinogen binding and expression of P-selectin at rest and in response to agonist stimulation, whereas amlodipine enhanced P-selectin expression and atenolol increased fibrinogen binding in response to agonists. Atenolol did not block the stimulatory effects of epinephrine on ADP-induced platelet activation. GTN neutralized the proactivatory effects of amlodipine, whereas the effects of atenolol and amlodipine were not additive.

CONCLUSIONS

The three main classes of antianginal medication have different and possible clinically relevant effects on platelet behavior in vivo, nitrates causing inhibition of aggregation (fibrinogen binding) and degranulation (P-selectin expression), calcium antagonists enhancing degranulation, and beta-blockers enhancing aggregation.

Verapamil and angiotensin-converting enzyme inhibitors in patients with coronary artery disease and reduced left ventricular ejection fraction

Verapamil is effective as antianginal medication but contraindicated in patients with congestive heart failure. Angiotensin-converting enzyme (ACE) inhibitors improve survival in patients with congestive heart failure but have limited effect on patients with angina pectoris. No studies have been published on the combined treatment with verapamil and ACE inhibitors in patients with stable angina pectoris and left ventricular dysfunction. We performed an open study in 14 patients with angina pectoris and ejection fraction < 40%. The patients received verapamil 180 mg and trandolapril 2 mg twice daily for 3 months. We found a significant increase in ejection fraction from 28 +/- 6 to 35 +/- 11 (p < 0.03), wall motion index from 1.0 +/- 0.3 to 1.2 +/- 0.3 (p < 0.03), exercise duration from 6.9 +/- 2.5 to 7.7 +/- 2.9 minutes (p < 0.01), and ratio of exercise to rest rate-pressure product from 2.2 +/- 0.4 to 2.5 +/- 0.6 (p < 0.02). Use of nitroglycerin and number of angina pectoris attacks were both significantly reduced after 3 months of treatment. These findings support the hypothesis that the combination of verapamil and trandolapril is useful in patients with attenuated left ventricular function and angina pectoris.

Anti-ischemic intervention as prognosis improvement in patients with coronary artery disease, with special focus on verapamil

Angina pectoris is a significant risk predictor in patients with atherosclerotic heart disease. The major complications are myocardial infarction, heart failure, and arrhythmias. Plaque rupture turns stable angina pectoris into acute coronary syndrome by provoking platelet aggregation and thereby thrombus formation. Verapamil significantly inhibits platelet aggregation and thrombus formation, which may be one of several reasons for the protective effect of verapamil on reinfarction in patients recovering from myocardial infarction. Ischemia may lead to left ventricular dilation and diastolic dysfunction, and thereby heart failure. In postinfarction patients intervention with verapamil significantly reduced the use of diuretics compared with placebo, indicating that anti-ischemic intervention may prevent heart failure. Ventricular arrhythmias are significantly associated with arrhythmic as well as non-arrhythmic death. The lack of preferential association of ventricular arrhythmias with arrhythmic death rather than nonarrhythmic death may imply that arrhythmias are provoked by ischemia. Antiarrhythmic intervention in postinfarction patients significantly increases death and arrhythmic events compared with placebo, especially in patients with residual ischemia. This may be due to a significant slowing of conduction during ischemia in patients treated with antiarrhythmic agents. In animal studies anti-ischemic agents prevent or suppress ventricular arrhythmias during ischemia, whereas traditional antiarrhythmic drugs have no effect or even worsen the arrhythmias, especially during episodes with elevated sympathetic activity. Verapamil significantly reduces plasma norepinephrine levels and the norepinephrine release during ischemia, whereby ventricular arrhythmias may be prevented. Also, supraventricular arrhythmias are significantly associated with myocardial ischemia and are prevented by verapamil. In patients with atherosclerotic heart diseases, angina pectoris is a significant risk predictor, but anti-ischemic intervention should be considered even in patients in whom the major problem is heart failure or arrhythmias.

Risk of gastrointestinal haemorrhage with calcium antagonists in hypertensive persons over 67 years old

BACKGROUND

Calcium antagonists are used frequently in management of hypertension. In addition to their cardiovascular effects, these drugs inhibit platelet aggregation. Therefore we examined whether the use of calcium antagonists was associated with an increased risk of gastrointestinal haemorrhage (GIH).

METHODS

A prospective cohort study was conducted from 1985 through 1992 on 1636 hypertensive persons aged > or = 68 years living in three communities. The participants were taking beta-blockers, angiotensin-converting enzyme (ACE) inhibitors, or calcium antagonists; those taking combinations of these drugs were excluded. The incidence of GIH was assessed by surveying hospital discharge diagnoses and deaths. Age, gender, disability, arterial pressure, other drugs, and comorbid conditions were examined as confounders.

FINDINGS

Compared with beta-blockers (4819 person-years, 65 events), after adjustment for confounders the relative risk for GIH associated with ACE inhibitor (772 person-years, 13 events) was 1.23 (95% CI 0.66-2.28) and with calcium antagonists (1510 person-years, 42 events) it was 1.86 (1.22-2.82). The risks for verapamil, diltiazem, and nifedipine did not differ significantly. The results were unchanged when the analyses were restricted to severe events (GIH in conjunction with blood transfusion or death).

INTERPRETATION

Calcium antagonists were associated with an increased risk of GIH in this population. Therefore caution is needed in prescription of these agents to old patients who have other risk factors for gastrointestinal bleeding.

A controlled trial of verapamil in patients after acute myocardial infarction: results of the calcium antagonist reinfarction Italian study (CRIS)

A multicenter, double-blind, randomized, placebo-controlled trial was conducted to assess the effects of verapamil on total mortality, cardiac mortality, reinfarction, and angina after an acute myocardial infarction. All patients, aged 30 to 75 years, consecutively admitted for acute myocardial infarction between 1985 and 1987 to the participating centers, and without contraindications to verapamil or history of severe heart failure were enrolled. Seven to 21 days (mean 13.8) after myocardial infarction, 531 patients were randomized to verapamil retard 360 mg/day, and 542 patients to placebo. At baseline, the 2 groups of patients had similar characteristics. Mean age was 55.5 years and 91% were men. During a mean follow-up of 23.5 months, 5.5% of the patients died. No differences between verapamil and placebo were observed in total mortality (n = 30 and 29, respectively) and cardiac death (n = 21 and 22, respectively). The verapamil group had nonsignificant lower reinfarction rates (n = 39 vs 49). The number of patients developing angina was significantly less in the verapamil group (n = 100 vs 132, RR = 0.8, 95% confidence interval 0.5 to 0.9). There were no differences in discontinuation of therapy caused by adverse reactions. This trial showed no effect of verapamil on mortality. The lower reinfarction rates found in the verapamil group are in agreement with the results of other studies.

Platelet activation during myocardial ischaemia: a contributory arrhythmogenic mechanism

Experimental and clinical observations of the involvement of platelets in the pathophysiology of myocardial ischaemia indicate the importance of interactions between these formed elements and the heart. The aim of this review is to outline evidence linking platelet activation, myocardial ischaemia and infarction, and to present evidence for a link between platelet activation, arrhythmogenesis and sudden death. A brief review of platelet physiology and pharmacology is provided, with a review of the cardiac electrophysiological effects of ischaemia and the electrophysiological effects of platelet-derived substances. The concept that platelet activation during myocardial ischaemia is a contributory arrhythmogenic mechanism is discussed.

ACE inhibitors and calcium antagonists in the treatment of congestive heart failure

The increased mortality after myocardial infarction is related to the risk of reinfarction, sudden death, and the development and progression of heart failure; in congestive heart failure it is due to the progression of heart failure and sudden death. ACE inhibitors have been proven to prevent cardiovascular events, especially the progression of heart failure, in postinfarct patients with reduced ejection fraction and heart failure in the SAVE and AIRE trials. In patients with congestive heart failure, ACE inhibitor treatment has prevented cardiovascular death and reduced morbidity due to progressive heart failure in the SOLVD trials. In post-myocardial infarction patients, the calcium antagonist nifedipine did not affect mortality or morbidity; diltiazem improved prognosis in patients without congestive heart failure and in patients with non-Q-wave infarction; and verapamil improved prognosis by prevention of reinfarction and sudden death. Combination treatment with both verapamil, which has pronounced antiischemic properties and prevents sudden death and reinfarction, and an ACE inhibitor, which prevents the progression of heart failure, is a possibility for future cardiovascular therapy that should be evaluated.