Silent myocardial ischaemia in patients referred for coronary bypass surgery because of angina: a comparison with patients whose symptoms were well controlled on medical treatment.

The frequency and characteristics of silent ischaemia were prospectively studied in 114 patients with confirmed coronary artery disease and angina. Fifty seven patients who had angina that was not adequately controlled by standard medications were referred for elective coronary artery bypass surgery (group 1). Fifty seven other patients had symptoms that were well controlled on medical treatment (group 2). Patients underwent treadmill exercise testing (n = 109) and 48 hours of ambulatory ST segment monitoring (total 5125 hours). Patients in group 1 had more severe coronary artery disease and a shorter time to 1 mm ST segment depression and maximal exercise. Twenty two patients in group 1 (38%) and 16 in group 2 (28%) had greater than or equal to 1 episode of silent ischaemia during 48 hours of ST monitoring. There was no significant difference in the mean frequency of silent ischaemic episodes in 24 hours between the two groups (group 1 0.72 v group 2 0.64); however, the mean frequency of painful ischaemic episodes in 24 hours was greater in group 1 patients (0.51) than in group 2 (0.11). In both groups the frequency of silent ischaemia was significantly related to a positive exercise test, as was the total duration of silent ischaemia. The circadian variation of silent ischaemia showed a peak of episodes in the evening in both groups. The frequency of silent ischaemia in patients with coronary artery disease and angina receiving standard antianginal medications was not related to the severity of symptoms, but was significantly related to a positive exercise test. Thirty three percent of the patients studied had evidence of silent ischaemia during 48 hours of ambulatory ST segment monitoring; however, only four patients (3.5%) had frequent (>/=5) daily episodes of silent ischaemia.     

Silent myocardial ischaemia in patients with angiographically proven coronary artery disease

Twenty patients with angiographically proven coronary artery disease (CAD) were evaluated by Holter monitoring for assessment of total ischaemic burden during daily activities. Thirteen patients revealed ischaemia on Holter monitoring (symptomatic-2, silent-4 and both types-7). As compared to symptomatic ischaemia, the silent myocardial ischaemic episodes were more frequent (25 vs 10 episodes), longer in duration (15-53 minutes vs 8-45 minutes), occurred at lower heart rates (65-75/minute (mean 68) vs 70-90 per minute (mean 76) and silent ischaemic episodes exceeded symptomatic ones in both morning (10 vs 4) and evening (15 vs 6) peaks. Occurrence of symptomatic as well as silent ischaemia had no relation to rest, activity, left ventricular functions, and there was no difference in the extent (1-3mm) and type (horizontal or downsloping) of ST-segment depression. We conclude that in patients with significant coronary artery disease, silent myocardial ischaemia is more frequent than the symptomatic ischaemia during daily activities. It occurs at lower heart rates, lasts longer, and bears no relation to rest, activity or left ventricular function. Evening peaks may be as frequent or more than the morning peaks. Holter monitoring thus is helpful for assessment of total ischaemic burden in CAD patients.     

Survival of patients with mild angina or myocardial infarction without angina: a comparison of medical and surgical treatment

A group of 390 patients with mild angina pectoris or myocardial infarction without subsequent angina had early coronary bypass operation. Five year survival was significantly higher (95.4%) than in a similarly selected medically treated group (88.5%) reported before. One death occurred in the 30 day postoperative period. Five year survival in the 179 patients who had internal mammary artery grafts was 98.9%. Survival for patients with mild angina and satisfactory left ventricular function (96.2%) was significantly higher than in the medical subset (91.3%). In the patient population studied, five year survival was higher in patients who had early bypass operations than in those who did not.     

Silent myocardial ischaemia in chronic stable angina: a study of its frequency and characteristics in 150 patients

One hundred and fifty unselected patients with documented coronary artery disease were studied to establish the frequency and characteristics of silent myocardial ischaemia. Patients underwent ambulatory ST segment monitoring off all routine antianginal treatment (total 6264 hours) and exercise testing (n = 146). Ninety one patients (61%) had a total of 598 episodes of significant ST segment change, of which 446 (75%) were asymptomatic. Twenty seven patients (18%) had only painless episodes; 14 (9%) patients only painful episodes; 50 patients (33%) had both painless and painful episodes. The mean number of ST segment changes per day was 2.58 (1.95 silent); however, 11 patients (7%) had 50% of all silent episodes, and 48 patients (32%) had 91% of all silent episodes. Fifty nine patients (39%) had no ST segment changes on ambulatory monitoring, and 73 patients (49%) had no evidence of silent ischaemia. Episodes of silent ischaemia occurred with a similar circadian distribution to that of painful ischaemia, predominantly between 0730 and 1930. There was a similar mean rise in heart rate at the onset of both silent and painful episodes of ischaemia. Silent ischaemia was significantly more frequent in patients with three vessel disease than in those with single vessel disease, and was also significantly related to both time to 1 mm ST depression and maximal exercise duration on exercise testing. There was a highly significant relation between the mean number and duration of episodes of silent ischaemia in patients with positive exercise tests when compared with those with negative tests. No episode of ventricular tachycardia was recorded in association with silent ischaemic change.     

Unstable angina and evolving myocardial infarction following coronary bypass surgery: pathogenesis and treatment with interventional catheterization

Effective therapy for patients with unstable angina or evolving myocardial infarction following coronary bypass surgery requires accurate delineation of the pathoanatomy and prompt intervention. We therefore performed cardiac catheterization in 10 consecutive patients: four with acute myocardial infarction and six with refractory unstable angina (NYHA class IV). All patients with acute myocardial infarction were found to have completely thrombosed vein grafts supplying totally occluded native coronary arteries. In three patients with evolving myocardial infarction occurring within 4 weeks of coronary bypass surgery, graft thrombosis was caused by venous valves in two patients and a suboptimal anastomosis in a third. The fourth patient sustained a myocardial infarction 7 years after coronary bypass surgery with atherosclerotic plaque rupture causing vein graft thrombosis. Therapy with intragraft streptokinase resulted in complete clearing of thrombus, pain relief, and control of injury current in all four patients. Rest angina with concomitant ST and T wave changes occurred in six patients. In two patients symptoms occurred early (within 6 months), whereas angina developed 4 to 10 years after coronary bypass graft surgery in four patients. In the two patients with early recurrence of symptoms suboptimal anastomosis was found in one, while the other patient had a venous valve in the vein graft in conjunction with a stenosis in the native coronary artery. In three of four patients with late recurrence of angina, symptoms developed as a result of atherosclerotic stenosis in their vein grafts; in the fourth patient an occluded graft was found to supply a stenosed native coronary artery.(ABSTRACT TRUNCATED AT 250 WORDS)     

Ten-year survival of patients with mild angina or myocardial infarction without angina: a comparison of medical and surgical treatment

Ten-year survival percentages were calculated for groups of 407 initially medically treated patients and for 390 patients who had early coronary bypass surgery; all had either mild angina pectoris or myocardial infarction without subsequent angina pectoris. Uncensored actuarial survival was 77% for medical patients and 83% for the surgical group. For 179 patients who had internal thoracic (mammary) artery grafting as part of their procedures, survival was 91% in contrast to 76% for those who had vein grafts only. A sharp drop of the survival curve for the vein graft group after the seventh year was not shown for those who had internal thoracic artery grafts. Survival was 71% for 280 patients treated medically only.     

Survival of patients with mild angina or myocardial infarction without angina: a comparison of medical and surgical treatment.

A group of 390 patients with mild angina pectoris or myocardial infarction without subsequent angina had early coronary bypass operation. Five year survival was significantly higher (95.4%) than in a similarly selected medically treated group (88.5%) reported before. One death occurred in the 30 day postoperative period. Five year survival in the 179 patients who had internal mammary artery grafts was 98.9%. Survival for patients with mild angina and satisfactory left ventricular function (96.2%) was significantly higher than in the medical subset (91.3%). In the patient population studied, five year survival was higher in patients who had early bypass operations than in those who did not.     

Silent myocardial ischaemia in chronic stable angina: a study of its frequency and characteristics in 150 patients.

One hundred and fifty unselected patients with documented coronary artery disease were studied to establish the frequency and characteristics of silent myocardial ischaemia. Patients underwent ambulatory ST segment monitoring off all routine antianginal treatment (total 6264 hours) and exercise testing (n = 146). Ninety one patients (61%) had a total of 598 episodes of significant ST segment change, of which 446 (75%) were asymptomatic. Twenty seven patients (18%) had only painless episodes; 14 (9%) patients only painful episodes; 50 patients (33%) had both painless and painful episodes. The mean number of ST segment changes per day was 2.58 (1.95 silent); however, 11 patients (7%) had 50% of all silent episodes, and 48 patients (32%) had 91% of all silent episodes. Fifty nine patients (39%) had no ST segment changes on ambulatory monitoring, and 73 patients (49%) had no evidence of silent ischaemia. Episodes of silent ischaemia occurred with a similar circadian distribution to that of painful ischaemia, predominantly between 0730 and 1930. There was a similar mean rise in heart rate at the onset of both silent and painful episodes of ischaemia. Silent ischaemia was significantly more frequent in patients with three vessel disease than in those with single vessel disease, and was also significantly related to both time to 1 mm ST depression and maximal exercise duration on exercise testing. There was a highly significant relation between the mean number and duration of episodes of silent ischaemia in patients with positive exercise tests when compared with those with negative tests. No episode of ventricular tachycardia was recorded in association with silent ischaemic change.     

Prevalence and treatment of proximal left subclavian artery stenosis in patients referred for coronary artery bypass surgery

The left internal mammary artery (LIMA) is currently used in most coronary artery bypass graft (CABG) surgeries due to excellent long-term patency. Left subclavian artery stenosis (SAS) proximal to the LIMA origin can cause a steal syndrome leading to myocardial ischemia or LIMA failure. We retrospectively evaluated the records of 608 consecutive patients referred for CABG at our institution between October 1, 2004 and October 1, 2006 and identified 226 patients (37%) who underwent left subclavian angiography immediately after diagnostic coronary angiography. Significant left SAS was found in 6 of those 226 patients (2.7%). Subclavian angiography did not result in any complications. All left SAS lesions were successfully stented, followed by CABG surgery (using the LIMA artery) after 22+/-7 days. Left subclavian angiography in patients referred for coronary artery bypass surgery has low risk and may identify a small proportion of patients with significant proximal left SAS. Stenting of proximal left SAS can be accomplished before CABG with low risk and excellent short-term outcomes.     

Coronary angioplasty for medically refractory unstable angina in patients with prior coronary bypass surgery

Percutaneous transluminal coronary angioplasty (PTCA) has been applied with good results to selected patients with unstable angina and to selected patients who have had prior bypass surgery. The population with prior bypass and unstable angina has not been specifically evaluated. This report reviews the results of angioplasty of 45 vessels in 34 patients with medically refractory unstable angina and at least one prior bypass heart surgery. Of these 34 patients, 32 had rest angina; 14 had resting electrocardiographic changes, all 34 were on aspirin 325 mg QD, 31 were on a calcium blocker, 22 were on a beta blocker, 9 were on intravenous nitroglycerin, and 5 required intraaortic balloon counterpulsation for temporary stabilization. Angioplasty of a vein graft was attempted in 17 patients; the left internal mammary was attempted in 4 patients; 24 native coronary arteries in 15 patients were attempted; 3 of the native arteries were protected left main arteries. Of the LIMA angioplasties, 3 were successful; in the 1 unsuccessful case, the occluded anterior descending artery was opened. Of the 17 vein grafts, 16 were successful: 1 had an acute occlusive syndrome and went to surgery with a balloon pump and bail out catheter; his recovery was uneventful. Of the 24 native artery angioplasties, 22 were successful: one patient was technically unsuccessful in the only vessel attempted; he went to semiemergent surgery and recovered uneventfully. In the other, a right coronary lesion was successfully dilated, but an occluded anterior descending artery was not opened. There were no deaths or in-hospital myocardial infarctions.(ABSTRACT TRUNCATED AT 250 WORDS)     

Cardiac medical therapy in patients after undergoing coronary artery bypass graft surgery: a review of randomized controlled trials

The purpose of this paper is to review the randomized controlled trial (RCT) data investigating cardiac medical therapy for patients after coronary artery bypass grafting (CABG). We identified RCTs with > or =100 enrolled patients that examined the impact of cardiac medical therapy on outcomes > or =1 year after CABG. The MEDLINE database was searched for trials conducted between 1966 and 2004 on the following medications: aspirin, antilipid agents, beta-blockers, calcium channel blockers (CCBs), nitrates, and angiotensin-converting enzyme (ACE) inhibitors. Both aspirin and antilipid agents were found to reduce the progression of atherosclerosis and the occurrence of graft occlusion. Cardiovascular events were decreased with antilipid agents. In small trials, beta-blockers and CCBs failed to decrease the incidence of cardiovascular events. No RCTs examined nitrates, and one small RCT documented a reduction in cardiovascular events among patients treated with ACE inhibitors. We conclude that few RCTs have examined the efficacy of cardiac medical therapy in post-CABG patients. Based on current RCT evidence, aspirin and antilipid agents should be used routinely after CABG. However, current data do not support the use of beta-blockers, CCBs, and nitrates, and more evidence is needed regarding the use of ACE inhibitors.     

Myocardial ischaemia and angina in the early post-infarction period: a comparison with patients with stable coronary artery disease.

OBJECTIVE--To evaluate Holter and treadmill responses in patients with stable angina or recent myocardial infarction in order to compare the mechanisms of ischaemia and its symptomatic expression in these two groups. PATIENTS--75 patients with ischaemic ST segment depression on both a treadmill stress test and ambulatory Holter monitoring. Group A comprised 35 patients with stable angina, and group B comprised 40 patients in the early period after infarction. SETTING--The coronary care unit and cardiology department of a district general hospital. DESIGN--A prospective, between group, comparative study. RESULTS--Treadmill test showed demand driven ischaemia in both groups. Although ST depression occurred at comparable rate-pressure products and workloads, it was associated with angina in 80% of group A compared with only 40% of group B (p < 0.005). During Holter monitoring, ST depression was associated with an attenuated increase in rate in group A and almost no increase in rate in group B (18.2% v 3.7%; p < 0.005), suggesting that reductions in myocardial oxygen delivery were contributing to the ischaemic episodes, particularly in group B. Ischaemic episodes were more commonly silent during Holter monitoring, particularly patients in group B, only two of whom experienced angina in association with ST depression. Spectral and non-spectral measures of heart rate variability were significantly reduced in group B compared with group A. Patients with silent exertional ischaemia in group A had significantly less heart rate variability than patients who experienced angina but this difference was not seen in group B. CONCLUSION--In stable angina, myocardial ischaemia is usually painful and demand driven, whereas in the early period after infarction silent, supply driven ischaemia predominates. The failure of myocardial ischaemia to provoke symptoms in some patients with stable angina may be related to autonomic dysfunction affecting the sensory supply to the heart. In the early period after infarction despite clear evidence of autonomic dysfunction, other mechanisms must also be important as there was no tendency for the reduction in heart rate variability to be exaggerated in the subgroup with silent exertional ischaemia.     

Comparison of costs of percutaneous transluminal coronary angioplasty and coronary bypass surgery for patients with angina pectoris

To determine the costs of a procedure, the total costs of the department that provides the service must be considered and, in addition, the direct cost of the specific procedure. Applying this principle to the cost accounting of angioplasty and bypass surgery results in a direct, i.e. procedural, cost, including the initial hospital stay, of respectively 8694 Dfl and 20,987 Dfl. A review of the follow-up data for the first year after the original intervention revealed a 2% reintervention rate for bypass surgery, while this percentage was 29% for angioplasty. Adding the first year costs involved with reinterventions to the procedural costs results in a 1-year cost of angioplasty and bypass operation of 13,625 Dfl and 21,363 Dfl, respectively. It is concluded that because of reinterventions in the first year, a mark up of 57% on the procedural cost of angioplasty must be added to cover 1-year costs, while for bypass surgery this is only 1%. Nevertheless, the 1-year cost for angioplasty is still 36% less than for bypass surgery. As reinterventions after PTCA may stay considerably higher than for CABG for several years, the mark-up percentages will be substantially higher for longer time spans. This may tend to equalize the total costs of PTCA and CABG over time spans of perhaps 5-8 years. Sufficient data are not available to verify this statement. Clinicians must realize that choosing the most appropriate procedure is not only a matter of medical assessment but also a matter of cost effectiveness. CABG can be seen as an 'investment decision' while PTCA tends to become a decision with characteristics of 'maintenance planning'!     

Troponin-T in patients with unstable and stable angina pectoris undergoing coronary bypass surgery

BACKGROUND: Troponin-T is a sensitive indicator of minor myocardial damage during coronary bypass surgery. METHODS: Troponin-T levels were assessed before and repeatedly for 64 hours after coronary bypass surgery in 100 patients with unstable and 100 with stable angina pectoris. RESULTS: Postoperative troponin-T levels rose significantly within 6 hours followed by a decline until 64 hours. In unstable patients who had pain within two days and an acute myocardial infarction within two weeks before the operation (Braunwald class IIIC), Troponin-T rose to high levels that persisted for 64 h. Sixty-seven percent of these patients had an elevated troponin-T >0.10 microg/l already before the operation and a perioperative myocardial infarction was recorded in 27%. In contrast, postoperative troponin-T levels in remaining patients classified as unstable were similar to those in patients with stable angina. Elective operations in the control group were performed with a low risk of adverse postoperative events. CONCLUSIONS: Patients with Braunwald class IIIC unstable angina suffered to a great extent myocardial cell damage following coronary bypass surgery.     

Medical treatment of patients with stable angina pectoris referred for coronary angiography: failure of treatment or failure to treat

BACKGROUND: Patients referred for elective coronary arteriography because of stable angina pectoris frequently do not receive appropriate medical therapy prior to arteriography. Persistence of symptoms due to lack of appropriate therapy may influence the decision to catheterize and the treatment chosen following catheterization. HYPOTHESIS: The present study evaluates whether patients with stable angina pectoris referred for cardiac catheterization received optimal therapy prior to the procedure. We also evaluated whether medical therapy was optimized as a result of the hospitalization for catheterization. METHODS: We evaluated prospectively the adequacy of medical therapy in 333 consecutive patients undergoing elective coronary arteriography. Of these, 160 had stable angina pectoris as their main problem and constituted the study group. RESULTS: Mean duration of angina was 7.5 +/- 6.3 months. Canadian Cardiovascular Society angina grade 1 was present in 20, grade 2 in 77, grade 3 or 4 in 63 patients. Arteriography showed a > or = 50% coronary stenosis in 141 of 160 patients. Aspirin was used by 96%, and 86% received at least one drug aimed at relieving anginal symptoms: beta blockers in 69%, calcium blockers in 30%, and long-acting nitrates in 29%. Antianginal drugs and drugs aimed at treating risk factors were usually taken at a low, subtherapeutic dosage. Only 35 of 110 patients taking beta blockers had a resting heart rate of <60/min. Following catheterization, 88 of 141 patients with coronary stenosis of > or = 50% underwent percutanous intervention and 5 had urgent surgery. Optimization of treatment was advised in only 7 of 48 patients for whom medical therapy or elective surgery was recommended. CONCLUSION: Patients with stable angina pectoris are frequently referred for cardiac catheterization without making a serious attempt to control their symptoms by medical therapy. Risk factors are undertreated. With proper pharmacotherapy, many patients might have become asymptomatic and have chosen not to undergo catheterization and subsequent percutaneous interventions.     

Long-term results of coronary artery bypass surgery for unstable angina: incidence of mortality,myocardial infarction,and angina resumption

To determine if routine treadmill testing would be helpful in identifying patients at high risk for subsequent events, the first 81 patients to undergo coronary artery bypass0 surgery for unstable angina pectoris at Stanford University Medical Center were reevaluated at four intervals after surgery. Evaluations, including assessment of angina pectoris and a treadmill test, were done at mean times of 18,40, and 72 months after surgery. At a mean time of 90 months postoperatively, angina status was determined in survivors. The prevalence of angina rose from 19% during the first year to 53% during the fourth and fifth postoperative years. Cardiac deaths and myocardial infarctions were frequent during the first postoperative year, and were more frequent in patients with three-vessel disease and those with one or more severely narrowed coronary arteries which were not bypassed. Cardiac events were rare between 12 and 36 months after operation; clinical and treadmill variables did not predict these events. During the fourth and subsequent postoperative years, the incidence of cardiac events increased. While the presence of stable angina pectoris was the clinical variable most useful prognostically, treadmill testing added additional independent prognostic information (p<0.0001). During the intervals between visits 1 and 2, and visits 2 and 3, cardiac events were ten times more frequent in persons with a maximal heart rate of 130 beats/min or less on the treadmill at 18 and 40 months. We conclude that the prevalence of angina increased steadily during the first 5 postoperative years. Myocardial infarction and cardiac death rates were high during the first postoperative year, low during the second and third postoperative years, and then began to rise thereafter. The early events were more frequent in persons with three-vessel disease and one or more severely narrowed coronary arteries which were unbypassed. The late events were more frequent in persons with a maximal heart rate of 130 beats/min or less on treadmill exercise testing. No other clinical or treadmill variables added additional independent prognostic information.