Studies on ergometer exercise testing. II. Effect of previous myocardial infarction, digoxin, and beta-blockade on exercise electrocardiography

The results of exercise electrocardiography were studied in a random sample of 317 subjects with clinical suspicion of coronary artery disease. In 278 patients with coronary artery disease the rate of false negative tests was 18% with and 12% without previous myocardial infarction. If ST elevation was considered a negative response, the corresponding values were 25% and 13%, respectively, p less than 0.01. The greatest prevalence of negative tests was seen after anterior myocardial infarction: 27% or 42% when ST elevation was not included into positive responses. The sensitivity of exercise-induced ST depression for the presence of multivessel disease was lower after anterior infarction (67%) than in other patients with previous infarction (86%), p less than 0.01. The corresponding specificities were 71% and 22%, respectively, p less than 0.005. If ST elevation was included into positive responses these differences were abolished. In subjects without myocardial infarction the sensitivity was 89% and specificity 43%. Digitalized patients had somewhat higher sensitivity in the exercise electrocardiogram than those without digoxin, 90% vs. 81% (p less than 0.05), but the difference was not seen with exclusion of ST elevation. The specificity was not influenced by digitalis. beta-blockade had no effect on the sensitivity or specificity, but the prevalence of postexercise ST evolution was lower with (11%) than without (30%) beta-blockade. The prevalence of slowly ascending ST depression was reduced by three factors: the presence of digitalis in patients without previous myocardial infarction, infarction itself, and the extent of coronary artery disease. We conclude that exercise electrocardiography has only a limited value in prediction of multivessel disease.(ABSTRACT TRUNCATED AT 250 WORDS)

Studies on ergometer exercise testing. I. Significance of the type of ST-segment response, sex, and chest pain

Ergometer exercise electrocardiographic (EECG) data were surveyed in a series of 328 patients (277 men and 51 women) subjected to coronary arteriography. The sensitivity and specificity of EECG for coronary artery disease (CAD) were 84% and 54%, respectively. The predictive accuracy of a positive test for CAD was 95% in men and 81% in women. The predictive accuracy of a negative test was 25% in men and 62% in women. When slowly ascending ST depression was considered insignificant, the sensitivity of EECG declined to 71%, with an increase in specificity to 64%. CAD was present in 89% of the patients with slowly ascending ST depression and 65% of them had a multivessel disease. Seventy-two subjects had postexercise ST-segment elevation. The predictive value of this sign for CAD was 94%. Exercise-induced chest pain had quite a similar diagnostic significance as EECG. The prevalence of CAD in patients with a history of typical angina was 94% in both sexes. Atypical chest pain was associated with normal coronary arteriography in 59% of males and 100% of females.

Conversion of paroxysmal atrial fibrillation to sinus rhythm by intravenous pirmenol. A placebo controlled study

The efficacy of pirmenol (a class I antiarrhythmic agent) as a converter of paroxysmal atrial fibrillation was investigated. Forty patients without congestive heart failure or a history of sinus node disorder were randomly allocated to receive either intravenous pirmenol (50-100 mg) or placebo in a double blind trial. In 12 of 20 patients sinus rhythm was restored 2-16 minutes after pirmenol, and in 3 of 20 patients in the control group it returned within one hour. A nodal escape rhythm was seen during sinus slowing in one patient, but in other patients there was no sinus arrest, atrioventricular conduction disturbance, or hypotension. The ventricular rate was slightly increased in patients in whom sinus rhythm was not restored by pirmenol. The results indicate that pirmenol has an antifibrillatory effect on the atria. Sinus rhythm was restored rapidly after intravenous administration. It was well tolerated in patients with atrial fibrillation of recent onset.

Acute haemodynamic effects of the antiarrhythmic agent pirmenol in cardiac patients: a comparison with lidocaine

The acute haemodynamic effects of pirmenol, a new Class 1 antiarrhythmic agent, were investigated in a double-blind comparison with lidocaine and placebo. Three groups of 10 patients each received either pirmenol as a 50 mg intravenous injection followed by a 2.5 mg min-1 infusion, or lidocaine as a 75 mg injection followed by a 3 mg min-1 infusion, or placebo. Mean plasma pirmenol concentrations during the 30 min infusion period were 2.3-2.5 mg l-1, and were considered to be therapeutically effective. Compared to measurements taken during a baseline phase of 15 min duration, pirmenol increased heart rate by 10 beats min-1 (P less than 0.001) and mean arterial pressure (MAP) by 5 mmHg (P less than 0.001). It also increased systemic vascular (P less than 0.05) and pulmonary arterial resistances (P less than 0.01). Left ventricular end-diastolic pressure (LVEDP) was not increased significantly. Cardiac index and left ventricular work index remained unchanged. Lidocaine induced a comparable increase in MAP (6 mmHg; P less than 0.001) and elevated LVEDP (2.8 mmHg; P less than 0.05) and did not affect left ventricular work index. Echocardiographic left ventricular ejection fraction was reduced more by pirmenol (-0.05; P less than 0.001) than by lidocaine (-0.03; P less than 0.05), but the greater reduction may partly be explained by the increase in heart rate. Primenol did not induce excessive circulatory responses or side-effects in any patient. Intravenous administration of pirmenol results in increased heart rate and afterload but has little effect on preload. The myocardial depressant effect is relatively slight, and comparable to that of lidocaine.

A long-term double-blind comparison of doxazosin and atenolol in patients with mild to moderate essential hypertension

The efficacy and safety of doxazosin and atenolol were compared following once-daily administration for up to 1 year, with a minimum of 20 weeks' active treatment. According to response, patients received doxazosin 1-16 mg day-1 or atenolol 50-100 mg day-1. Mean daily doses at the final efficacy assessment (between 20 weeks and 1 year) were doxazosin 11.8 mg and atenolol 94.2 mg. Atenolol produced somewhat greater falls in blood pressure than doxazosin. The differences were statistically significant in the supine but not in the standing position. A small mean reduction in heart rate was produced by doxazosin whereas atenolol produced a marked bradycardia. Analysis of the same patient group at 20 weeks revealed similar overall profiles of activity except that atenolol produced greater falls in blood pressure than in the longer term analysis. Serum concentrations of HDL/total cholesterol ratio were raised in the doxazosin treatment group and lowered in the atenolol group. Triglyceride concentrations fell in the doxazosin group and rose in the atenolol group. Significant differences (P less than 0.001) were observed between treatment groups for these parameters, all differences being in favour of doxazosin. Pharmacokinetics of doxazosin, measured at steady state in 36 patients, showed dose-related plasma concentrations, a mean half-life of about 12 h and relatively low intersubject variation. The incidence of side-effects was slightly greater for patients in the doxazosin group. Drug-related side-effects were mostly mild to moderate in severity with no serious drug-related occurrences in either treatment group. No serious drug-related abnormalities in laboratory biochemistry and haematology tests were observed in either treatment group.

Antiarrhythmic efficacy of pirmenol in the treatment of premature ventricular complexes

We assessed the antiarrhythmic effectiveness, therapeutic plasma concentrations and adverse effects of pirmenol in 16 patients with frequent (mean 933 h-1) premature ventricular complexes (PVC). Progressive increase in dose to a maximum of 200 mg twice daily suppressed PVC in a majority of patients. By preset criteria 11 patients (69%) exhibited an effective suppression of PVCs whereas in 5 patients (31%) the suppression was inadequate despite therapeutic plasma concentrations. The responders exhibited an 87% mean reduction of PVCs and a 97% reduction in repetitive PVC. This therapeutic effectiveness was verified against placebo by repetitive 24-hour ECG monitorings recorded in a double-blind cross-over fashion. The plasma trough concentration during the effective dose averaged 1.31 +/- 0.67 mg-1 (SD). The efficacy was maintained with the twice daily regimen despite an elimination half life of 6.3 +/- 1.7 h (SD) but a slight decrease in PVC suppression was observed towards the end of the administration interval. Pirmenol was well tolerated but aggravation of the arrhythmia occurred in one patient who shared an associated excessive prolongation of the Q-T interval, a feature observed with quinidine-like class I agents.

Sequential internal mammary artery (IMA) grafts in coronary artery bypass surgery

Since 1972, double or triple left IMA bypasses have been made on 61 consecutive patients with a total of 123 distal anastomoses to the LAD or to the LD branches of the LAD. There were 54 additional vein grafts with 102 distal anastomoses. The number of single IMA grafts in the same period of time was 400. Hospital mortality was 2 patients (3.3%), with a late mortality of 7 patients (11.3%), 2 of them being heart-related, one of hypernephroma, one suicide, and of unknown cause in the remaining 3 patients. Five patients refused postoperative angiography. There were 50 patients with one or more postoperative angiograms available for the analysis after a mean follow-up time of 35.1 (0.5 to 128) months. The late patency of the left IMA anastomoses was 97% (98/101) and 82.4% (84/102) of the vein anastomoses. There were 2 anastomotic left IMA occlusions to the LD at 2 weeks and 10 months, respectively, and to LAD at 13 months. No left IMA graft had become completely occluded. According to the trend analysis, there was a 97.5% patency at 5 years, and 95.7% at 10 years with left IMA grafts compared to 78.4 and 67.9, respectively, with vein grafts. Ten left IMA grafts were dilated, 2 narrowed and 36 unchanged at the late angiography. Sequential left IMA graft, in appropriate cases seems to result in the most superior patency rate of all types of grafts.

Prevention of progression of coronary atherosclerosis by treatment of hyperlipidaemia: a seven year prospective angiographic study

The progression of coronary atherosclerosis was assessed by repeat angiography in 28 patients and 20 controls with hyperlipidaemia (serum cholesterol concentration greater than 7.2 mmol/l (278 mg/100 ml) or serum triglyceride concentration greater than 2.0 mmol/l (177 mg/100 ml), or both) and symptomatic coronary artery disease of two or three vessels. Twenty eight patients (26 men and two women) were treated with diet and drugs (clofibrate or nicotinic acid, or both) to lower lipid concentrations. Twenty men taking part in a simultaneous study served as non-randomised controls. They received medical treatment for coronary artery disease but no treatment to reduce lipid concentrations. The initial levels of coronary risk factors and the angiographic state were comparable in the two groups. In the 28 patients total cholesterol, total triglyceride, and low density lipoprotein cholesterol concentrations were reduced by an average 18%, 38%, and 19% respectively by treatment for hyperlipidaemia and high density lipoprotein cholesterol concentration was increased on average by 10%. The treatment maintained these concentrations during a follow up of seven years. By all criteria coronary lesions progressed significantly less in the patients than the controls: the angiographic state remained completely unchanged in nine (32%) of the patients compared with only one (8%) of the surviving controls; of the arterial segments at risk, 46 (16.5%) progressed in the patients compared with 50 (38.2%) in the controls (p less than 0.001); and the coronary obstruction increased less in patients than in controls (p less than 0.05). Cardiac survival was 89% in seven years in the patients compared with 65% in five years in the controls (p less than 0.01). The anginal symptoms diminished or remained stable in 16 of the 24 patients who survived until the end of the study. The progression of coronary atheromatosis was significantly greater in those patients who during the seven years of treatment had an average total cholesterol concentration, VLDL plus LDL cholesterol concentration, or ratio of LDL to HDL cholesterol concentration above the respective median value than in those with the corresponding values below median. On the other hand, the patients with HDL cholesterol concentrations above the median during treatment showed less progression than those with lower HDL cholesterol concentrations. The increase in coronary obstruction was inversely related to the average HDL cholesterol concentration during treatment. The progression was not, however, related to LDL cholesterol concentration during treatment.(ABSTRACT TRUNCATED AT 400 WORDS)

The effect of dipyridamole and warfarin on the patency rate of coronary artery bypass grafts

Seventy consecutive patients who had undergone coronary artery bypass surgery were postoperatively treated with either dipyridamole or warfarin for 6 months. The dipyridamole series consisted of 28 patients given 150 mg dipyridamole 3 times daily and the warfarin series, of 42 patients who received the appropriate daily dose of warfarin needed to maintain the prothrombin time within the therapeutic range. The majority of patients in both series belonged to the NYHA class III. Sixty-one percent of the patients in the dipyridamole series and 66% of those of the warfarin series had triple vessel disease. In all, 70 and 105 coronary artery branches were bypassed in the dipyridamole and warfarin series, respectively. This resulted in 2.5 distal anastomoses per patient in each series. The patency of the grafts was confirmed angiographically. There was no mortality during the 23.6 +/- 2.4 months follow-up period in the dipyridamole series or the 12.8 +/- 2.7 months in the warfarin series. The patency rates were 95.7% and 88.6% in the dipyridamole and warfarin series, respectively. It is apparent that dipyridamole is not less effective than warfarin in preventing postoperative coronary graft occlusion.

Progression of coronary artery disease in randomized medical and surgical patients over a 5-year angiographic follow-up

Progression of coronary artery disease (CAD) was assessed prospectively in a randomized series of 36 medically treated and 42 surgically treated patients with angina pectoris. The medical patients were reexamined after 5 years and the surgical patients 3 weeks, 1 year and 5 years after operation. Sixty-seven percent of the medical patients and 69% of the surgical patients had progression. The frequency of new lesions in initially normal segments after 5 years in the medical group was 6.7%, versus 4.1% in ungrafted normal segments in the surgical group (p = 0.05 less than 0.010). The frequency of progression in abnormal arteries was 24.1% in the medical group, versus 22.6% in the ungrafted arteries of the surgical group (p = 0.90 less than 0.95). The rate of progression of obstructed segments proximal to the graft over 5 years was 43%, versus 27% of the corresponding segments in the medical group (p less than 0.01). Progression took place in 11.6% of normal segments proximal to the graft, versus 2% of the corresponding segments in the medical group (p less than 0.05); 69% of progression occurring in segments proximal to the graft had reached total occlusion, versus 38% of the corresponding segments in the medical group (p less than 0.01). Progression developed in 3.9% of segments distal to the graft, versus 3.1% of the corresponding segments in the medical group. Progression takes place at identical rates in medically treated patients and in ungrafted arteries and segments distal to the graft in surgical patients. Proximal to the graft the rates differ and total occlusions appear as early as 3 weeks after operation.

Perioperative myocardial infarction in coronary bypass surgery

Thirteen of 199 consecutive patients undergoing coronary artery bypass surgery revealed definite perioperative myocardial infarction (PMI) in electrocardiography (ECG). The occurrence of PMI was not higher in the group of 44 patients who had intermittent aortic cross-clamping than in those patients treated with cold chemical cardioplegia. In 83 patients serum MB isoenzyme of creatine kinase (CK) and LD1 isoenzyme of lactic dehydrogenase were determined. Patients with unchanged ECG had peak CK-MB levels of 0 to 49 U/l (mean 18.7 U/l +/- 2.6 SEM) at 18 hours postoperatively while patients with PMI showed CK-MB levels of 64-350 U/l (mean 207 +/- 53 U/l); the difference was significant (p less than 0.01). In patients with unchanged ECG, LD1 was 139 +/- 19 U/l and 594 +/- 95 U/l in those with PMI (p less than 0.01). Risk factors for PMI were: age greater than or equal to 60 years, coronary endarterectomies, or cardiopulmonary bypass time greater than or equal to 100 minutes. One patient died of PMI while the remaining patients had postoperative courses comparable to those patients without PMI.

Persistent improvement after coronary bypass surgery: ergometric and angiographic correlations at 5 years

One hundred patients with angina pectoris who fulfilled specific entry criteria were randomly assigned to either medical therapy or bypass surgery. These groups were subjected to annual exercise testing during a 5-year follow-up period. The degree of revascularization was assessed by graft and native vessel angiography at 3 weeks, 1 year and 5 years after the operation. The exercise tolerance of the medical group remained largely unchanged during the follow-up. Eighty-five to 95% of the patients were using beta-blocking compounds at the successive testing situations. The surgical group exhibited a sustained improvement in exercise tolerance: Total work increased by 39-66% (p less than 0.02-0.001) and maximal ergometric load by 23-35% (p less than 0.01-0.001), and maximal ST depression decreased by 39-61% (p less than 0.05-0.001). The use of beta-blocking compounds in the surgical group steadily increased, from 44% at 6 months after operation to 63% of patients at 5 years. Division of the surgical group into subsets of complete and incomplete revascularization revealed that the improvement was confined to complete revascularization. Thus, the improved exercise tolerance after bypass surgery was a result of successful reestablishment of effective coronary perfusion; despite graft attrition (15% in 5 years) and new lesions in the native arteries, this improvement persisted for 5 years with appropriate medical therapy.

Patency of sequential versus single vein grafts in coronary bypass surgery

The patency and graft flow of sequential (seq. SVBG) and single saphenous vein bypass grafts (single SVBG) in coronary bypass surgery were compared angiographically (mean follow-up 26 months) in 76 patients with 36 seq. SVBG (75 distal anastomoses) and 85 single SVBGs. The late patency of all seq. SVBGs anastomoses (94.7%) was higher than that of single SVBGs (80.0%). No early or late graft occlusions were seen in the side-to-side (SSA) anastomoses of the seq. SVBGs. The cine-angiographically determined mean volume flow in the proximal segments of the seq. SVBGs was significantly higher (p less than 0.001) than that in the distal segments of the seq. SVBGs or in the single SVBGs at both early and late follow-up. Despite the higher late patency rate (88.9% vs 80.0%) in the end-to-side anastomoses (ESA) of the seq SVBGs, the mean graft flow was significantly lower in the distal segments of seq SVBGs than in the single SVBGs (71 ml/min vs. 109 ml/min, p less than 0.05).

The effect of sequential versus single vein aortocoronary bypass surgery on resting left ventricular function

To study the effectiveness of sequential vein grafts in coronary bypass surgery, left ventricular (LV) function was serially estimated in 28 patients with sequential grafts and compared with that in 24 patients with multiple single vein grafts. Early patency of sequential grafts was 98% vs. 94% for single veins. Late patency (mean 28 months after operation) of sequential veins was 97% vs. 85% for single vein grafts (mean 32 months after operation). Various parameters of resting LV function (pressure, volumes, ejection fraction, regional contraction score, mean velocity of fiber shortening) showed only slight and non-significant changes during the angiographic follow-up in the sequential vein graft group, with the exception of LVEDP, which was significantly lower at the late follow-up (p less than 0.05). There was an apparently spurious highly significant decline in fiber shortening velocity in the sequential graft group (p less than 0.001). Division of the series into subgroups of complete or incomplete revascularization did not improve the predictive power of resting LV function. The data reveal that sequential vein grafts are comparable to multiple single vein grafts as far as the influence on LV function at rest is concerned.

Response of blood pressure and plasma norepinephrine to propranolol, metoprolol and clonidine during isometric and dynamic exercise in hypertensive patients

The effects of metropolol (beta 1-selective), propranolol (nonselective) and clonidine (central alpha-stimulant) on plasma norepinephrine, blood pressure and heart rate were assessed at rest, during isometric work and dynamic exercise in 15 patients with moderate hypertension. Metroprolol resulted in a lower diastolic blood pressure during isometric and dynamic exercise that propranolol, which was paralleled by a lower plasma norepinephrine level during dynamic work; both beta-adrenergic blocking compounds resulted in a lower heart rate in all test situations than that obtained with clonidine; clonidine produced similar control of diastolic blood pressure to that obtained with the beta-adrenergic blocking agents, but did not clearly attenuate the systolic blood pressure response to dynamic exercise. Plasma norepinephrine concentrations tended to be lowest following clonidine, especially during dynamic work. The findings support the hypothesis that the central action of clonidine inhibits peripheral release of norepinephrine, but is insufficient to attenuate cardiac stimulation by physical exercise. The fact that propranolol caused higher plasma norepinephrine concentrations than metoprolol during exercise may explain the difference in the blood pressure responses during exercise.

Antiarrhythmic significance of dosing intervals in beta receptor blocking therapy of hypertension with acebutolol

Six hypertensive patients with daily ventricular arrhythmias underwent a double-blind crossover study to examine whether a once daily regimen of beta receptor blockade was equipotent in antihypertensive and antiarrhythmic activity to a twice daily regimen. Acebutolol, a relatively cardioselective beta blocking compound with intrinsic sympathomimetic properties, was given in two regimens: 200 mg twice daily or 400 mg once daily. Ventricular ectopic beats were analyzed both during physical exercise and with multiple 24 hour ambulatory electrocardiographic (Holter) recordings. Serum concentrations of acebutolol and its acetyl metabolite were determined using high pressure liquid chromatography. The two regimens of acebutolol were equally potent in reducing the blood pressure and heart rate at rest and during physical exertion. The hourly heart rates during 24 hours were reduced to the same extent by both regimens. The single daily 400 mg dose did not significantly reduce the incidence of arrhythmias, whereas 200 mg twice daily evoked a significant reduction during 24 hours. Serum concentrations of acebutolol were twice as great with the twice daily regimen as with the single dose. Both treatments significantly shortened the Q-Tc interval. The data suggest that, despite apparent beta receptor blockade and good blood pressure control, beta blocking agents with a relatively short plasma half-life lose their antiarrhythmic potency when administered on a once daily basis. This property seems to be more related to the plasma concentration of the compound than to the degree of clinically assessed beta receptor blockade.

Red cell flexibility and oxygen affinity in patients with angina pectoris and normal coronary arteries

Plasma viscosity, haemoglobin-oxygen affinity and red cell flexibility were determined in 16 patients who had angina pectoris but no objective evidence for spasms or obstructions in the coronary arteries. Reference data were obtained from healthy controls and from a group of patients with angina pectoris and multivessel coronary artery disease. In the non-coronary angina group mean plasma viscosity (+/- SD) was in the normal range (1.3 leads to 0.06 centipoise). The same was true for haemoglobin-oxygen affinity (P50: 25.9 +/- 1.7 mmHg). Both red cell rigidity (71 +/- 20 mmHg) and red cell fragility (142 +/- 95 mg/l) were significantly higher (p les than 0.0025) than in the control group (54 +/- 10 mmHg and 63 +/- 29 mg/l, respectively). The group with coronary artery obstructions did not differ from the controls. Thus rigid red cells appear to be related to the syndrome of angina pectoris despite normal coronary arteries. In the light of previous findings of local perfusion abnormalities in these patients, inflexible erythrocytes could be an additional factor compromising myocardial capillary flow.

Prevention of early reocclusion by dipyridamole and ASA in arterial reconstructive surgery

In this prospective study 364 patients were subjected to different types of arterial reconstructive surgery. The patients were randomly divided into four groups according to the type of antithrombotic medication given. During the hospitalization period there were no reocclusions in the dipyridamole/ASA group of 93 patients compared with 12 reocclusions in the control group of 86 patients. The difference was statistically highly significant. The difference between the control group and the given dipyridamole or ASA was not statistically significant. Dipyridamole and ASA were tolerated well by the patients in this clinical trial. This was the first clinical investigation to prove the effectiveness of dipyridamole and ASA medication in the prevention of reocclusions in arterial reconstructive bypass surgery.

Prevention of deep venous thrombosis and thrombo-embolism by dipyridamole and acetylsalicylic acid after reconstructive arterial surgery

A series of 400 consecutive patients subjected to reconstructive arterial surgery were randomly allocated into four equal groups in order to study the effect of dipyridamole and acetylsalicylic acid (ASA) in the prevention of deep venous thrombosis and pulmonary embolism. There were 11 drop-outs. In the dipyridamole-ASA group there were no thrombotic complications while in the control group without antithrombotic therapy five cases of deep venous thrombosis and two cases of fatal pulmonary embolism were encountered (p < 0.05). In the groups receiving either dipyridamole or ASA alone two and four cases of deep venous thrombosis, respectively, were found. It is concluded that treatment with dipyridamole and ASA combined is useful in preventing postoperative thrombotic complication after peripheral vascular reconstructive surgery.

A follow-up study of coronary bypass patients without patent grafts

A series of 295 coronary bypass patients who had early and late postoperative coronary angiography included 6 cases (2%) whose grafts had all become occluded. These patients were followed up using both functional classification and repeated exercise testing. In three patients the functional classification improved early after surgery (less than or equal to 1 year) with improved exercise capacity in two. Two of these patients had perioperative myocardial infarction. During follow-up (3--8 years after surgery) only one of the patients who improved initially retained the improved capacity. There were three deaths. It is concluded that some unsuccessfully revascularized patients exhibit initial improvement which is only exceptionally maintained over longer periods. The likely explanation for pain relief is perioperative myocardial infarction.