Correlation between coronary microvascular function and angina status in patients with stable microvascular angina.

BACKGROUND: Classical anti-ischemic drugs are the first-line form of treatment in patients with microvascular angina (MVA), but they often fail to achieve a satisfactory control of angina symptoms. It is unknown whether there is any relation between improvement of angina status and changes in microvascular function induced by classical anti-ischemic drugs in MVA patients. AIM: To assess whether, in MVA patients, the effects of classical anti-ischemic drugs on symptoms and quality of life (QoL) are related to changes in coronary microvascular function. PATIENTS AND METHODS: We studied 51 patients (59±10 years; 15 men) with MVA. Coronary blood flow (CBF) response to adenosine (ADO) and to cold pressor test (CPT), Seattle Angina Questionnaire (SAQ) and EuroQoL scale were assessed at baseline, in pharmacological washout, and after 12 months under anti-ischemic therapy. Patients were divided into 2 groups: (1) Group 1 included patients with no improvement of QoL (EuroQoL score change < 10 points); (2) Group 2 included patients with QoL improvement (increase in EuroQoL score ≥ 10 points). RESULTS: At baseline, the 2 groups were similar in age, gender, cardiovascular risk factors, CBF response to ADO and to CPT, SAQ and EuroQoL scores. At follow-up the 2 groups differed only for beta blockers use (27% vs. 88% in group 1 and 2, respectively; p < 0.001). A significant improvement in SAQ score was observed only in group 2. CBF response to both ADO and CPT showed a similar improvement in the 2 groups. No relation was found between changes in coronary microvascular function and in angina status. CONCLUSIONS: In MVA patients beta-blockers are more effective than other anti-ischemic drugs in improving angina symptoms. The improvement of angina status does not seem to be mediated by changes in coronary microvascular function.

Cardiovascular impairment in a patient with acute myelitis.

STUDY DESIGN: Case report. OBJECTIVE: to report and discuss the development of sudden symptomatic sinus bradycardia in a 35-year-old woman with acute myelitis. CASE REPORT: A 35-year-old woman presented rapidly progressive weakness and hypoesthesia in the left hemibody. Five days after symptom onset, she developed symptomatic sinus bradycardia up to 30 b.p.m. Bradycardia was completely resolved ∼36 h after its onset. RESULTS: Cervical spine magnetic resonance imaging showed a focal T2-hyperintense intramedullary lesion at C2 level, with moderate cord swelling. The lesion involved bilaterally dorsal funiculi, and left lateral and ventral funiculi. Cardiac I-123 metaiodobenzylguanidine (MIBG) scintigraphy showed a decreased cardiac MIBG uptake suggesting sympathetic denervation. CONCLUSION: The most likely explanation for bradycardia in our patient is the myelitis-related disruption of descending vasomotor pathways, resulting in sympathetic hypoactivity. Our case extends the spectrum of the clinical presentations of cervical myelitis and emphasizes the importance of careful cardiac monitoring in acute phase of cervical myelitis.

The patient with chronic ischemic heart disease. Role of ranolazine in the management of stable angina.

Ischemic heart disease (IHD) is a major cause of death in Western Countries and accounts for very high costs worldwide. In this review we discussed the pathogenesis, symptoms, diagnosis, prognosis and management of chronic IHD. In particular, we discussed about the percutaneous coronary interventions and coronary artery bypass grafting, as well as to clinical trials that evaluated the advantages of one approach versus another. Pharmacological treatment is among major objectives of the review and for each class of therapeutic agents an evaluation of well-conducted clinical trials is provided. The most important drug classes in IHD treatment are betablockers, calcium channel blockers, nitrates, antiplatelet agents, and ACE-inhibitors. In addition to these agents, also new treatment options are evaluated in patients with stable IHD. Ranolazine, in particular, is a innovative anti-anginal drug with a great successful in the management of patients with refractory angina. A pharmacological as well as clinical profile of this drug is provided.

Atrial fibrillation and the pharmacological treatment: the role of propafenone.

BACKGROUND: Atrial fibrillation is the most frequent cardiac rhythm disturbance, with prevalence increasing with age. This disease is a major risk factor for ischaemic stroke. The costs resulting from atrial fibrillation are really impressive. Pharmacological agents are the first line therapy for the management of atrial fibrillation. Antiarrhythmic drugs are used to terminate arrhythmias, as acute treatment for conversion of recent onset atrial fibrillation, and to maintain sinus rhythm, as chronic therapy for prevention of atrial fibrillation recurrences. Among antiarrhythmic agents, drugs that inhibit early sodium current (as propafenone) are proven effective in atrial fibrillation. In this review, the most relevant data on propafenone are provided. DISCUSSION: The development of a sustained-release formulation of propafenone allowed to reduce the wide fluctuations in plasma levels observed with the immediate release preparation, improving compliance and adherence to therapy, by simplifying the dosing regimen from 3 to 2 daily doses. Propafenone resulted an effective measure as acute treatment for conversion of recent onset atrial fibrillation, and to maintain sinus rhythm, as chronic therapy for prevention of atrial fibrillation recurrences. In several clinical studies, strong increases of arrhythmia-free periods as well as marked increases in time to recurrence of symptomatic atrial fibrillation, such as paroxysmal supraventricular tachycardia and paroxysmal atrial fibrillation were observed. In particular, well-designed clinical studies demonstrated in large patient populations the efficacy of propafenone at several doses. At the suggested doses propafenone is usually well tolerated. CONCLUSION: The risk of increased occurrence of regular supraventricular arrhythmia or paroxysmal supraventricular tachycardia has been overestimated for propafenone, because this adverse event was seen in all treatment groups, including placebo, with the same (and low) frequency.

Effect of bariatric surgery on peripheral flow-mediated dilation and coronary microvascular function.

BACKGROUND AND AIMS: To assess the effects of bariatric surgery (BS) on peripheral endothelial function and on coronary microvascular dilator function. METHODS AND RESULTS: We studied 50 morbidly obese patients (age 38 ± 9, 13 M) who underwent BS and 20 comparable obese controls (age 41 ± 11, 6 M) without any evidence of cardiovascular disease. Peripheral vascular dilator function was assessed by brachial artery diameter changes in response to post-ischemic forearm hyperaemia (flow-mediated dilation, FMD). Coronary microvascular function was assessed by measuring coronary blood flow (CBF) velocity response to i.v. adenosine and to cold pressor test (CPT) in the left anterior descending coronary artery by transthoracic Doppler echocardiography. The tests were performed at baseline and at 3-month follow-up. At baseline, FMD and CBF response to adenosine and CPT were similar in the 2 groups. Compared to baseline, FMD at follow-up improved significantly in BS patients (5.9 ± 2.7% to 8.8 ± 2.4%, p < 0.01), but not in controls (6.3 ± 3.2% vs. 6.4 ± 3.1%, p = 0.41). Similarly, a significant improvement of CBF response to adenosine (1.63 ± 0.47 to 2.45 ± 0.57, p < 0.01) and to CPT (1.43 ± 0.26 to 2.13 ± 0.55, p < 0.01) was observed in BS patients but not in controls (1.55 ± 0.38 vs. 1.53 ± 0.37, p = 0.85; and 1.37 ± 0.26 vs. 1.34 ± 0.21, p = 0.48, respectively). The favourable vascular effects of BS were similar independently of the presence and changes of other known cardiovascular risk factors and of basal values and changes of serum C-reactive protein levels. CONCLUSIONS: Our data show that, in morbidly obese patients, together with peripheral endothelial function, BS also improves coronary microvascular function. These effects suggest global improvement of vascular function which can contribute significantly to the reduction of cardiovascular risk by BS reported in previous studies.

Hypertension therapy and cardiovascular protection. Effects of angiotensin II receptor block with Valsartan.

OBJECTIVES: Arterial hypertension and its pharmacological control are discussed in view of the high cardiovascular risk due to lack of target blood pressure achievement. It is, therefore, underlined the need for a highly effective therapy, able to provide protection from organ damage through a marked antihypertensive activity. In addition to this basic property, also compliance of the patient to therapy is needed, in order to avoid that the effects of therapeutic measures should result fruitless. DISCUSSION AND CONCLUSIONS: An answer to this problem appears now offered by a recent class of antihypertensive agents, the angiotensin II receptor blockers (ARBs). Among them valsartan has been described, providing an overview of methodologically adequate clinical studies, evaluating the efficacy, even at long-term, and safety. Valsartan has been compared with other antihypertensive agents of proven efficacy, mainly amlodipine, showing a better clinical profile. A wide room was finally left to the problem of adherence to therapy, whose lack is associated very frequently with marked increases in cardiovascular risk, due to absent or insufficient blood pressure control. This implies significant increases of health costs, as documented in numerous Countries, mainly following the higher need for hospitalization. On the other hand, it is also well documented the pharmacoeconomic benefit associated to ARBs use, particularly with valsartan.

Endothelial dysfunction as assessed by flow-mediated dilation in patients with cardiac syndrome X: role of inflammation.

BACKGROUND: Endothelial dysfunction, reduced coronary flow reserve and increased markers of inflammation are detectable in cardiac syndrome X (CSX). In this study we investigated the relation between inflammation and systemic endothelial function in CSX patients. METHODS: We studied 42 CSX patients (55 +/- 6 years, 14 men) and 20 healthy subjects (52 +/- 7 years, 9 men). Systemic endothelial function was assessed by flow-mediated dilation (FMD) of the brachial artery after 5-minute of forearm cuff inflation. Serum C-reactive protein (CRP) was measured by a high-sensitivity method. RESULTS: FMD was significantly lower in CSX patients compared to controls (4.8 +/- 4.4 vs. 13.7 +/- 4%, p < 0.001), whereas CRP levels were higher in CSX patients than in controls (2.7 +/- 2.4 vs. 0.7 +/- 0.4 mg/L, p = 0.001). In CSX patients FMD showed a significant inverse correlation with CRP levels, even after adjustment for potentially confounding variables (r = -0.34, p = 0.006). CONCLUSION: An impaired FMD is detectable in CSX patients, suggesting a generalized abnormality in vascular function. Subclinical inflammation se is to play a significant role in the impairment of endothelium-dependent vasodilator function of these patients.

Contrast transoesophageal echocardiography remains superior to contrast-enhanced cardiac magnetic resonance imaging for the diagnosis of patent foramen ovale.

AIMS: In 30-40% of patients with acute ischaemic stroke, the cause remains undefined (cryptogenic stroke). Contrast transoesophageal echocardiography (TEE) is considered the gold standard for patent foramen ovale (PFO) detection. Recently, however, cardiac magnetic resonance (CMR) has also been applied to detect PFO. In this study, we compared the diagnostic value of CMR and TEE in detecting PFO in a group of patients with apparently cryptogenic stroke. METHODS AND RESULTS: Twenty-five patients (age 50 ± 13 years, 16 males) with apparently cryptogenic ischaemic stroke underwent contrast-enhanced TEE and contrast CMR for detection of possible PFO. Both imaging studies were performed during Valsalva manoeuvre. PFO grading results were assessed visually both for TEE and for CMR, according to the entity of contrast passage in the left atrium (grade 0 = no PFO; grades 1, 2, and 3 = mild, medium, and wide PFO, respectively). TEE detected PFO in 16 patients (64%). Contrast-enhanced CMR identified a PFO in 7 (44%) of these patients. TEE showed a grade 1 PFO in five patients, a grade 2 PFO in eight patients, and a grade 3 PFO in three patients. Of these patients, CMR failed to identify PFO in all five patients with a grade 1 PFO, in one patient with a grade 2 PFO, and one patient with grade 3 PFO according to TEE. None of the nine patients without PFO at TEE was shown to have a PFO at CMR. When compared with TEE, the present methodology of CMR had a sensitivity of 50%, specificity of 100%, negative predictive value of 31%, and a positive predictive value of 100%. CONCLUSION: Our data suggest that TEE is the cornerstone imaging diagnostic test to detect and characterize PFO in patients with ischaemic stroke, and is shown to be better compared with the current CMR sequences.

Low glucose blood levels are associated with abnormal cardiac sympatho-vagal balance in type 2 diabetic patients with coronary artery disease.

BACKGROUND AND OBJECTIVES: Glycemic control has been suggested to improve prognosis in diabetic patients, but recent trials failed to show benefits from intensive glycemic control. Hypoglycaemic episodes or large variability in glucose blood levels causing a sympatho-vagal imbalance of cardiac autonomic function (CAF) might play a role in this result. In our study we assessed whether blood glucose fluctuation may be related to variations in CAF during daily life in diabetic patients with coronary artery disease (CAD). MATERIALS AND METHODS: Twelve patients with type 2 diabetes mellitus with CAD (65+/-4 years, 2 women) underwent simultaneous 48-hour ECG Holter monitoring and continuous interstitial glucose measurements. The highest and lowest glucose levels for each 3-hour segments of the day were identified and heart rate variability (HRV) parameters were measured on Holter recordings on 5-minute intervals centred on these times. RESULTS: Overall, 294 glucose levels were available for analysis. In the whole population several HRV indices were significantly lower in correspondence of the lowest glucose blood levels and this difference was much more evident in patients who were not taking beta-blockers, than in patients who were taking beta-blockers. A significant, although mild, correlation was found between glucose blood levels and several time-and frequency domain HRV variables in patients not taking beta-blockers, but not in these on beta-blockers therapy. DISCUSSION: Our data suggest that, in type 2 diabetic patients with CAD, hypoglycaemic episodes are associated with depressed HRV and that beta-blocking agents are able to contrast this relation. These interesting results merit to be investigated in a larger population of patients.

Cardiac adrenergic nerve function and microvascular dysfunction in patients with cardiac syndrome X.

OBJECTIVE: To assess whether abnormalities in cardiac uptake of (123)I-metaiodobenzylguanidine (MIBG) correlate with coronary microvascular dysfunction in patients with cardiac syndrome X (CSX). SETTING: University hospital. PATIENTS: 29 patients (aged 59 (SD 7) years, 11 men) with typical CSX and a matched group of 20 healthy subjects (aged 56 (7) years, 8 men) were studied. INTERVENTIONS: Planar and single photon emission computed tomography (SPECT) MIBG myocardial scintigraphy was performed in all subjects. Coronary flow response (CFR) to adenosine and to cold pressor test (CPT) in the left anterior descending (LAD) coronary artery was assessed in all CSX patients and in 12 controls by transthoracic Doppler echocardiography. MAIN OUTCOME MEASURES: Abnormalities in cardiac MIBG scintigraphy were observed in 25 CSX patients (86.2%), but in no healthy control (p<0.001). Compared to controls, CSX patients showed a lower heart/mediastinum (H/M) ratio of MIBG uptake (1.69 (0.24) vs 2.2 (0.3), p<0.001) and a higher cardiac MIBG defect score (25 (22) vs 4 (2), p = 0.002). Both CFR to adenosine (3.31 (1.1) vs 1.94 (0.6), p<0.001) and CFR to CPT (2.35 (0.5) vs 1.63 (0.4), p<0.001) were lower in CSX patients than in controls. In CSX patients, however, no correlation was found between MIBG H/M ratio and CFR to adenosine (r = 0.17; p = 0.38) and to CPT (r = -0.28; p = 0.13), as well as between MIBG uptake score in the LAD territory and CFR to adenosine (r = 0.14; p = 0.47) and to CPT (r = 0.06; p = 0.73). CONCLUSION: Our data show striking abnormalities in cardiac adrenergic nerve function and in coronary microvascular function in CSX patients. However, no significant relation between the two abnormalities was found. Further studies are needed to clarify the mechanisms and the role of MIBG defects in CSX patients.

Effect of primary coronary intervention on heart rate variability and left ventricular function in patients with acute myocardial infarction.

AIM: Several studies showed that primary percutaneous coronary interventions (PCI) have a favourable impact on left ventricular remodeling and heart rate variability (HRV) both at short- and long-term follow-up in patients suffering an acute myocardial infarction (AMI). However, no previous study investigated the relationship between left ventricular remodeling and changes in HRV during follow-up in AMI patients treated by primary PCI. METHODS: We studied 28 patients with AMI (57+/-8 years, 27 men), treated by PCI within 12 hours of symptom onset. Patients underwent a 24-hour ECG Holter recording and left ventricular ejection fraction (LVEF) echocardiographic assessment before discharge, and at 1-month and 6-month follow-up. HRV was measured in the time- and frequency-domain. RESULTS: A significant improvement of both time- and frequency-domain HRV variables was observed at 1-month and at 6-month follow-up with the most significant changes being found for standard deviation of normal-normal beat intervals (SDNN) in the time-domain (95.5+/-26.1 ms vs 125.5+/-29.8 ms vs 142.8+/-28.8 ms, respectively; P<0.001) and for very low frequency (VLF) amplitude in the frequency-domain (36.7+/-9.8 ms vs 44.1+/-11.1 vs 48.9+/-12.2 ms, respectively; P<0.001). In contrast, compared to basal values, LVEF was substantially unchanged at 1-month and 6-month follow-up (48.8+/-8.5% vs 50.8+/-10% vs 49.6+/-9%, respectively; P=0.25). At 6-month follow-up 11 patients showed an improvement of >or= 5% of LVEF, whereas 17 patients did not show any improvement of LVEF. HRV variables significantly improved in a similar way in these two subgroups both at 1-month and at 6-month follow-up. CONCLUSION: Our data demonstrate that, in AMI patients treated by primary PCI, HRV improves over time, independent of changes in LVEF. The clinical implications of these findings deserve to be addressed in future studies.

Prognostic value of ventricular arrhythmias and heart rate variability in patients with unstable angina.

OBJECTIVES: To assess the prognostic value of ventricular arrhythmias (VA) and heart rate variability (HRV) in patients with unstable angina. DESIGN: Multicentre prospective study. SETTING: 17 cardiological centres in Italy. PATIENTS: 543 consecutive patients with unstable angina and preserved left ventricular function (ejection fraction >or=40%) enrolled in the SPAI (Stratificazione Prognostica dell'Angina Instabile) study. METHODS: Patients underwent 24 h ECG Holter monitoring within 24 h of hospital admission. Tested variables were frequent ventricular extrasystoles (>or=10/h), complex (that is, frequent or repetitive) VA, and bottom quartile values of time-domain and frequency-domain HRV variables. Primary end points were in-hospital and six-month total and cardiac deaths. RESULTS: Eight patients died in hospital (1.5%) and 32 (5.9%, 29 cardiac) during follow up. Both complex VA and frequent extrasystoles were strongly predictive of death in hospital and at follow up, even after adjustment for clinical (age, sex, cardiac risk factors and history of myocardial infarction) and laboratory (troponin I, C reactive protein and transient myocardial ischaemia on Holter monitoring) variables. At univariate analysis bottom quartile values of three HRV variables (standard deviation of RR intervals index, low-frequency amplitude and low to high frequency ratio) were associated with in-hospital death, and bottom quartile values of most HRV variables predicted six-month fatal events. At multivariate Cox survival analysis reduced low-frequency amplitude was consistently found to be independently associated with fatal end points. CONCLUSION: In patients with unstable angina with preserved myocardial function, both VA and HRV are independent predictors of in-hospital and medium-term mortality, suggesting that these factors should be taken into account in the risk stratification of these patients.

Diagnostic and prognostic value of ST segment depression limited to the recovery phase of exercise stress test.

OBJECTIVES: To investigate the diagnostic and prognostic value of ST segment depression limited to the recovery phase of an exercise stress test, as compared with that of ST segment depression appearing during exercise. SETTING: Exercise stress test laboratory of a university hospital. PATIENTS AND DESIGN: Clinical and angiographic data were compared for 574 consecutive patients who developed ST segment depression during the active phase of an exercise test (group 1) and for 79 patients who developed ST segment depression only during the recovery phase of the exercise test (group 2). RESULTS: There were no differences between the two groups in major clinical features. Significant coronary artery stenoses were found in 488 group 1 patients (85%) and in 62 group 2 patients (78%, p = 0.14). Three vessel or left main disease was found in 166 (29%) group 1 and in 14 (18%) group 2 patients (p = 0.045). At a median follow up of 55.3 months of 321 group 1 and 54 group 2 patients, there were no significant differences in major cardiac events between the groups (univariate relative risk 0.81, 95% confidence interval 0.25 to 2.68, p = 0.72). CONCLUSION: The diagnostic and prognostic power of ST segment depression limited to the recovery phase of an exercise test is largely similar to that of ST segment depression induced during effort; thus, assessing ST segment depression during recovery can significantly improve the clinical information derived from exercise stress tests.

Platelet aggregability in cardiac syndrome X.

AIMS: To assess platelet aggregability at rest and in response to exercise in patients with cardiac syndrome X (anginal chest pain, ST-segment depression on exercise, angiographically normal coronary arteries). METHODS AND RESULTS: We performed a symptom/sign-limited exercise test in 31 patients with syndrome X, 25 patients with coronary artery disease and 29 healthy subjects. Platelet aggregability was measured in flowing whole blood at baseline, at peak exercise, and after 30 and 120 min, as the time to occlude a collagen/adenosine diphosphate coated ring (aggregation time). Resting aggregation time was shorter in syndrome X patients (83.2+/-12 s), compared to patients with coronary disease (94.0+/-18 s, P<0.01) and to healthy subjects (96.4+/-21 s, P<0.01). With exercise, aggregation time did not change in healthy controls, decreased in patients with coronary disease (-13.8 s at peak; 95% CI, -10.2, -17.3 s;P<0.001), but increased in syndrome X (+17.4 s 30 min after exercise; 95% CI, +10.4, +24.4 s;P<0.0001). The intravenous administration of an adenosine antagonist (theophylline) prevented the exercise-induced prolongation of aggregation time in syndrome X patients (n=11), but had no effect in healthy controls (n=11). CONCLUSION: Platelet aggregability at rest was increased in syndrome X patients, compared to patients with coronary artery disease and healthy subjects. In contrast to patients with coronary disease, however, platelet aggregability was reduced by exercise. This response was prevented by theophylline, strongly suggesting the involvement of adenosine.

[Headache and coronary disease]. / Cefalea e malattia arteriosa coronarica.

Myocardial ischemia usually results in typical anginal chest pain, but cardiac pain can occasionally only be referred to regions outside the thorax. Headache, however, is a very unusual expression of myocardial ischemia. Thus, the correct diagnosis of "cardiac headache" is difficult and requires a high dose of suspicion, but it can be crucial to avoid possible life-threatening events. The type and site of headache are not specific, but an episodic occurrence. A short duration and a relationship with exercise or emotional triggers should alert physicians on the possible cardiac origin of headache. Paradoxical relief and prevention of headache by sublingual nitrates are a strong clue to the diagnosis.

Spinal cord stimulation in patients with refractory anginal pain and normal coronary arteries.

BACKGROUND: Spinal cord stimulation (SCS) has been shown to be effective in patients with refractory angina and coronary artery disease. No previous study assessed the clinical effects of SCS in patients with refractory angina who present angiographically normal coronary arteries. METHODS: SCS was performed in 7 patients (4 men, 3 women, mean age 59.3 +/- 11 years) with refractory angina and normal coronary arteries. Clinical status was assessed 1 month after SCS device implantation and at a mean follow-up of 11 months (range 2-17 months) by: 1) an estimate of the number of anginal attacks and nitrate consumption in the 2 weeks prior to implantation and to follow-up visits; 2) a score of quality of life by a visual analogic scale; 3) a five-item questionnaire assessing effort angina and satisfaction with treatment; 4) treadmill exercise testing. RESULTS: At the last follow-up the number of anginal episodes (p < 0.001) and nitrate consumption (p < 0.004) were both reduced by SCS. Visual analogic scale score improved from 2.1 +/- 0.98 to 9.0 +/- 0.9 (p < 0.001) at 1 month and to 6.4 +/- 2.3 (p < 0.01) at the last follow-up. Questionnaire analysis showed that mild (p = 0.006) and moderate (p = 0.000) physical activity, as well as patient satisfaction with anginal status (p = 0.000) and with current treatment (p = 0.000) all improved by SCS. Finally, time to 1 mm ST segment depression, time to angina, and exercise duration were all prolonged by SCS. CONCLUSIONS: Our data point out that SCS may considerably improve anginal symptoms and exercise tolerance in a significant number of patients with refractory angina and normal coronary arteries and therefore it should be considered as a valuable treatment option in this group of patients.

Low-grade exercise enhances platelet aggregability in patients with obstructive coronary disease independently of myocardial ischemia.

Moderate and strenuous exercise is known to enhance platelet aggregability in patients with obstructive coronary artery disease (CAD), but the effect of low-grade exercise is not known. We assessed shear-induced platelet aggregability before and after mild exercise (less than or equal to stage III of the modified Bruce protocol) in 27 patients with documented CAD who were receiving aspirin and in 12 subjects without CAD (controls). Ex vivo platelet aggregability was assessed in flowing whole blood as the time to occlude a collagen and adenosine diphosphate-coated ring; shorter times indicated greater aggregability. Aggregability, plasma von Willebrand factor (vWF) antigen, platelet and white cell counts, and hematocrit were measured at baseline, immediately after exercise (peak), and at 30 and 180 minutes after exercise. Exercise of similar workloads induced myocardial ischemia in 14 patients (group 1), but not in the other 13 (group 2) nor in controls. Both patient groups showed a reduction in aggregation time at peak exercise compared with baseline (group 1: 84+/-17 seconds at peak vs 96+/-22 seconds at baseline; group 2: 84+/-20 seconds at peak vs 99+/-20 seconds at baseline; p <0.03 for both comparisons), with a return to baseline values within 180 minutes. No significant variation occurred in controls (89+/-18 seconds at peak vs 85+/-21 second at baseline). Changes in vWF antigen did not differ significantly among groups. Aggregation times did not correlate with hematocrit or platelet and white cell counts. Thus, even low-grade exercise transiently enhances whole blood platelet aggregability in patients with obstructive CAD, but not in controls. The effect is independent of myocardial ischemia, occurs despite aspirin, and is likely dependent on hemodynamic factors interacting with coronary obstructions or dysfunctional endothelium.