Time domain analysis of the signal averaged electrocardiogram in patients with a conduction defect or a bundle branch block

Doubts have been expressed about the clinical usefulness oftime domain analysis of the signal averaged electrocardiogramin patients with prolonged QRS complex duration. We studied147 patients using a signal averaged ECG (40–250 Hz) whoseQRS complex was longer than 100 ms. A baseline electrophysiologystudy was also performed in 128 of these patients. Seventy-sevenpatients had a minor (QRS <120 and >100 ms) conductiondefect. Thirty-seven of these 77 had either induced or spontaneoussustained ventricular tachycardia (group I) and 40 had no sustainedventricular tachycardia (group II). Seventy patients had a major(QRS120 and >100 ms) conduction defect, 44 of whom had sustainedventricular tachycardia (group A). The remaining 26 withoutthis condition formed Group B. Group I compared to group IIpatients had a longer filtered QRS duration (120·8 ±14 vs 104·5 ± 9·5 ms, P<0·001),a longer low amplitude signal duration (41 ± 12·1vs 31 ± 12·6 ms, P<0·0001) and a lowerroot mean square of the last 40 ms of the filtered QRS complex(27 ± 29·8 vs 35 ± 25·3 µV,P=ns). Group A compared to group B had a longer filtered QRSduration (157·7±20·2 vs 140·7±15·7 ms, P<0·001), a longer low amplitude signalduration (57·3 ±24·9 vs 37·8 ±20·3 ms P<0·001) and a lower root mean squareof the last 40 ms of the filtered QRS complex (14·3 ±11·2 vs 22·0 ± 10·5 1 P<0·01).Using conventional late potential criteria, the sensitivityand specificity of the signal averaged ECG for the detectionof sustained ventricular tachycardia patients with a minor conductiondefect were 89% and 75%, respectively. The same criteria appliedto patients with a major conduction defect were sensitive (sensitivity:87%) but non-specific (specificity: 50%). However, by usingmodified late potential criteria, such as the presence of twoof any of the following three signal averaged parameters: filteredQRS duration 145 ms, low amplitude signal duration 50 ms,root mean square of the last 40 ms of the filtered QRS complex17·5µV, we derived a non-optimal but still acceptablecombination of sensitivity (68%) and specificity (73%). We concludethat traditional late potential criteria can be applied in patientswith a minor conduction defect, but modification of these criteriais necessary to derive useful clinical information for riskstratification of patients with a QRS complex duration 120ms.     

Successful radiofrequency ablation of accessory pathways with the first energy delivery: the anatomic and electrical characteristics

Successful ablation of accessory pathways has been achievedat the first energy delivery site in some patients, but factorspermitting success at the first site are unclear. Accessorypathway location, surface and endocardial electrogram characteristicsin each location were analysed and compared between the patientswith first site block (group A, 34 patients) and those in whommultiple sites (median seven sites) were required (group B,133 patients). No patients with right free-wall pathways hadfirst site block. In group A surface electrocardiograms weremore pre-excited (QRS duration: 132±20 vs 120 ±l7ms, P<0·0l). For left free-wall and septal pathways,the interval from the onset of the earliest delta wave on surfaceelectrocardiogram to local ventricular activation (QRS-V) wasmore negative and the local atrioventricular interval (AV) wasshorter in group A; the positive predictive value of a QRS-V0 ms, an AV 30 ms and the presence of a possible accessory pathwaypotential was 67% for left free-wall and of a QRS-V -10 ms withan AV 30ms was 100% for septal pathways. During retrograde mappingof concealed left free-wall and right anteroseptal pathways(first site block was not achieved in other locations) the positivepredictive value of a local ventriculoatrial interval 30 mswas 55%. Accessory pathway location correlated strongly with the chancesof first site block, suggesting that anatomical features areimportant. Maximizing pre-excitation may be of benefit in achievingfirst site block. Delivery of energy to a site with specialendocardial electrogram features was associated with an increasedlikelihood of first site block.     

Echocardiographic wall motion abnormalities and the signal averaged electrocardiogram in the acute phase of a first myocardial infarction

We studied the relationship between wall motion abnormalitiesdetermined by echocardiography and the signal-averaged electrocardiogramin 82 consecutive patients during the acute phase of a firstmyocardial infarction. An abnormal signal-averaged electrocardiogramwas defined as the presence of two of the following criteria:a QRS duration 114 ms, a root mean square voltage (RMS) ofthe last 40 ms 25 µV and an amplitude signal lower than40µV lasting 39 ms. The left ventricle was divided into13 segments and the contraction pattern divided into akinesiaalone (including dyskinesia) (group A), hypokinesia alone (groupB) and both hypokinesia and akinesia (group C). An abnormal signal-averaged electrocardiogram was found in 14/82patients (17%) and was correlated with the persistence of occlusionof the infarct-related vessel (32% vs 9%. P < 0.02). In patientswith a patent vessel, the incidence of an abnormal signal-averagedelectrocardiogram was 14% in group A, 9% in group B and 0% ingroup C (NS). In patients with an occluded vessel an abnormalsignal-averaged electrocardiogram was found in 10% of groupA patients, in 36% in group B patients and in 75% of group Cpatients (P = 0.05). Our study suggests that the presence of hypokinetic areas duringthe acute phase of a first myocardial infarction and an abnormalsignal-averaged electrocardiogram indicate an occluded infarct-relatedvessel.     

When should we diagnose incomplete right bundle branch block?

An rSr' pattern with QRS duration of less than 0.12 s in theright precordial leads can be due to incomplete right bundlebranch block (which may progress to complete right bundle branchblock) or can be a normal electrophysiological variant. To identifyother ECG features that may help to distinguish between thesetwo possibilities, ECGs of 15 patients who progressed from normalto complete right bundle branch block through an intermediaterSr' pattern of incomplete right bundle branch block were analysed.The following features in the right precordial leads (V₁, V₂)that preceded or accompanied the appearance of the rSr' wereidentified: diminution of the S wave depth (100%), inversionof ratio of the S wave depth to SV₁,/SV₂ (93%), slurring ofthe downstroke or upstroke of the S wave (27%) and prolongationof the QRS duration to 0.10 s (73%). When a further 79 subjectswith rSr' pattern in the right precordial leads and QRS durationof <0.12 s were divided into those with SV₁/SV₂ ratio >1.0 and those with SV₁/SV₂ < 1.0, compared with the latterthe subjects with SV₁/SV₂ ratio > 1.0 were found to be significantlyolder (59.8±18.4 years vs 32.8±18.1 years, P<0.001),to exclusively show S wave slurring (37% vs 0%), and to morelikely have a QRS duration 0.10s (74% vs 7%). The findings indicatethat when faced with a single ECG showing an rSr' pattern inthe right precordial leads and QRS duration 0.12 s, severalother features, and in particular the relative sizes of theS waves in V₁ and V₂, may be useful in distinguishing rSr' dueto incomplete right bundle branch block from ‘normal’rSr'.     

Evaluation and prognostic significance of left ventricular diastolic function assessed by Doppler echocardiography in the early phase of a first acute myocardial infarction

AIM: To study the prognostic significance of left ventricular diastolicfunction evaluated by transmitral and pulmonary venous flowvelocities obtained in the early phase of a first acute myocardialinfarction in relation to later development of congestive heartfailure. METHODS: Pulsed Doppler echocardiography of transmitral and pulmonaryvenous flow was assessed in 65 consecutive patients with a firstmyocardial infarction within 1 h of arrival in the coronarycare unit. RESULTS: A univariate regression analysis identified age, left ventricularejection fraction 45%, mitral E deceleration time 130 ms, E/Aratio >1·5, peak pulmonary venous atrial flow velocity30 cm . s^–1 and a difference between mitral and pulmonaryvenous atrial flow duration >0 ms as variables significantlyrelated to the development of congestive heart failure. However,in a multivariate analysis only mitral E deceleration time 130ms and age were significant independent variables related tothe development of congestive heart failure during the firstweek following a first acute myocardial infarction. CONCLUSION: Assessment of left ventricular diastolic function complementsmeasurements of systolic function in the evaluation of cardiacfunction, and mitral deceleration 130 ms best identifies patientsat risk of development of congestive heart failure followingacute myocardial infarction.     

Spectral turbulence analysis of the signal-averaged electrocardiogram for predicfing inducible sustained monomorphic ventricular tachycardia in patients with and without bundle branch block

Spectral turbulence analysis of the signal-averaged electrocardiogramis a new method for identifying patients prone to sustainedmonomorphic ventricular tachycardia. In contrast to analysisin the time domain, it has been claimed to be applicable inpatients with bundle branch block. The aim of this study wasto assess the predictive value of spectral turbulence analysis,in relation to the inducibility of sustained monomorphic ventriculartachycardia, in patients with and without bundle branch block.One hundred and sixty nine patients, of whom 120 had a QRS duration 120 ms, were studied Forty-seven patients had inducible sustainedmononwrphic ventricular tachycardia and were compared to 122control patients. The overall sensitivity of the spectral turbulenceanalysis for predicting inducible ventricular tachycardia was77%, the spectficity 35% and the total predictive accuracy 47%.The limited predictive accuracy was mainly due to a lack ofd between patients with and without ventricular tachycardiain patients with a QRS duration 120 ms. In patients with QRS 120 ms, however, there were significant differences in allspectral turbulence parameters and the method had a sensitivityof 75%, a specificity of 72% and a total predictive accuracyof 73%. The diagnostic usefulness of spectral turbulence analysis isdependent upon normal QRS duration and the method is applicableonly to patients without bundle branch block.     

Balloon occlusion during coronary angioplasty as a model of myocardial ischaemia: reproducibility of sequential inflations

In order to evaluate the potential of balloon occlusion duringcoronary angioplasty as a model of myocardial ischaemia in manwe have measured coronary sinus blood flow (CSBF), myocardialoxygen consumption (MVO₂), lactate extraction (LER) and electrocardiographicchanges in 11 patients undergoing left anterior descending artery(LAD) angioplasty. Baseline measurements were made before ballooncrossing and between inflations. Four consecutive inflationseach of 60 s duration were made; 5 min return to baseline wasallowed between inflations. There was a significant reduction in CSBF and MVO₂ (ml min^–1)during inflations 2, 3 and 4 (CSBF: 121±6694±53,113±4999±42, 124±66102±41, P<0.02;MVO₂:11.3±6.6–9.1±3.9, 10.4±3.7–8.7±2.4,12.2±4.49.4±2.8, P<0.05). However during thefirst period of balloon occlusion there were inconsistent changesin coronary flow with an overall rise in mean flow (97±35128±80ml min^–1, P = NS) and an overall rise in mean myocardialoxygen consumption (9.6 ± 3.812.5 ± 7.5 ml min^–1,P = NS). There was lactate production during all four inflationsbut the changes during the first one did not achieve statisticalsignificance. These inconsistent changes during the first inflation were thoughtto be due to partial obstruction of the stenosis by the deflatedballoon before primary dilatation. The changes due to crossingand during the first two inflations were further investigatedin another group of 12 patients undergoing LAD angioplasty.Great cardiac vein flow (GCVF), CSBF, MVO₂ and LER were recordedat baseline, during crossing and during the first two inflations.With the deflated balloon across the stenosis there were nochanges in CSBF or MVO₂ but there was a fall in GCVF (103±2877±50,P = NS) and a significant fall in LER (77±5716±37,P<0.01). Although there was a fall during the first inflationin CSBF, GCVF, MVO₂ and lactate extraction none of these changeswere significant. During the second inflation these changeswere of greater magnitude and achieved statistical significance. While balloon occlusion during coronary angioplasty has thepotential of providing a model of ischaemia in man we have foundthe first inflation period unreliable, due to the variable degreeof occlusion by the deflated balloon. We suggest that only subsequentinflations after the primary dilatation are used for observations.These findings are of significance when evaluating the effectsof therapeutic interventions during PTCA. Various refinementsin measurements of the effects of ischaemia will improve thespecificity of the model.     

Subjective symptoms and well-being differ in women and men after myocardial infarction

The frequency of subjective cardiac and psychological complaintsamong men and women a year after a confirmed diagnosis of myocardialinfarction (MI) were compared. Among 660 survivors, 595 patientscompleted mailed questionnaires at home one year after the MI.There were 421 men, mean age 67.1±10.7 years, and 174women, mean age 72.1±10.6 years. Controlling for the significantly higher mean age among thewomen, the latter more often had a previous history of anginapectoris, 54.6% (P0.05) versus 42.9%, and heart failure, 24.7%versus 13.5% (P0.01). Despite these facts, the women were significantlyless often referred to CCU, 82.2% versus 91.7% (P0.05). Oneyear after the MI, controlling for differences in age and co-morbidity,women reported significantly higher frequencies of psychologicaland psychosomatic complaints, including sleep disturbances.These differences may have clinical implications for diagnosisand treatment of women with coronary heart disease.     

Exercise training in heart failure improves quality of life and exercise capacity

Aims Benefit from exercise training in heart failure has mainly beenshown in men with ischaemic disease. We aimed to examine theeffects of exercise training in heart failure patients 75 yearsold of both sexes and with various aetiology. Methods and Results Fifty-four patients with stable mild-to-moderate heart failurewere randomized to exercise or control, and 49 completed thestudy (49% 65 years; 29% women; 24% non-ischaemic aetiology;training, n=22; controls, n=27). The exercise programme consistedof bicycle training at 80% of maximal intensity over a periodof 4 months.Improvements vs controls were found regarding maximalexercise capacity (6±12 vs –4±12% [mean±SD],P<0·01)and global quality-of-life (2 [1] vs 0 [1] units [median {inter-quartilerange}],P<0·01), but not regarding maximal oxygenconsumption or the dyspnoea–fatigue index. All of thesefour variables significantly improved in men with ischaemicaetiology compared with controls (n=11). However, none of thesevariables improved in women with ischaemic aetiology (n=5),or in patients with non-ischaemic aetiology (n=6). The trainingresponse was independent of age, left ventricular systolic function,and maximal oxygen consumption. No training-related adverseeffects were reported. Conclusion Supervised exercise training was safe and beneficial in heartfailure patients 75 years, especially in men with ischaemicaetiology. The effects of exercise training in women and patientswith non-ischaemic aetiology should be further examined.     

Lipoprotein(a) as a risk predictor for cardiac mortality in patients with acute coronary syndromes

Aims Raised lipoprotein(a) concentrations are considered to be arisk factor for atherothrombotic diseases. We examined whetherbaseline concentrations were a risk factor for an adverse outcomein patients admitted with acute coronary syndromes. Methods and Results Five hundred and nineteen patients admitted with suspected acutecoronary syndromes were studied and followed prospectively fora median of 3 years. The prognostic significance of a baselinelipoprotein(a) concentration of 30mg.dl^–1or lower forsubsequent cardiac death was assessed in patients with myocardialinfarction (266) and unstable angina (197) and compared withother variables in regression models. In patients with myocardialinfarction, a baseline lipoprotein(a) concentration of 30mg.dl^–1wasassociated with a 62% increase in subsequent cardiac death comparedto the lower concentration group (29·8% vs 18·6%,Log rankP=0·04). In a multivariate regression model abaseline lipoprotein(a) concentration of 30mg.dl^–1retainedits significance as an independent predictor of cardiac death(P=0·037). In patients with unstable angina, baselineconcentrations of 7·9mg.dl^–1were found to be significantpredictors of cardiac death in univariate (P=0·021) andmultivariate (P=0·035) regression models. Conclusion Baseline lipoprotein(a) concentrations in patients admittedwith acute coronary syndromes are associated with an increasedrisk of cardiac death. For patients with myocardial infarctiona concentration of 30mg.dl^–1appears appropriate as a riskdiscriminator; for patients admitted with unstable angina, however,much lower concentrations of lipoprotein(a) appear to be prognosticallyimportant.     

Angioscopic evaluation of prolonged vs standard balloon inflations during coronary angioplasty: A randomized study

To study the immediate effects of prolonged total balloon inflationduring PTCA, 41 patients (44 lesions) with chronic-stable anginawere randomized for prolonged sequential inflations (three tofive inflations of 3 to 5 min each, for a total duration of 12 min, group 1, n=20 lesions) or ‘standard’ sequentialinflations (three to five inflations of 1 min each, for a totalduration of 3 min, group 2, n-24 lesions). The mean durationof total balloon inflation time was 958 ± 129 s in group1 vs 205 ±46 s in group 2. Results of angioplasty wereassessed on both angiography and percutaneous transluminal coronaryangioscopy performed immediately after the procedure. High qualityimaging of the coronary lumen and lesion morphology was possibleon angioscopy in all patients without any complications. Post-PTCAangiographic percent diameter stenosis was significantly lessin group 1 compared to group 2: 26 ± 10% vs 36 ±8% (P<0.05). On angioscopy, flaps were seen in 16 patientsin group 2, but in only six in group 1 (P<0.02). There wasno difference in the incidence of thrombi on angioscopy betweenthe two groups (group 1: nine cases, group 2: 10 cases). Sensitivityof angiographic detection of flaps and thrombi was poor: 10%and 12% respectively. One patient in each group developed alongitudinal dissection, detected on both angiography and angioscopy. Conclusions: (1) prolonged sequential balloon inflations leadto less residual luminal stenosis after PTCA, with a decreasedincidence of intimal flaps in comparison with standard inflations.(2) Post-PTCA transluminal coronary angioscopy is safe and offersbetter assessment of luminal effects of PTCA than angiography.     

Autonomic balance in patients with angina and a normal coronary angiogram

The pathophysiology of angina pectoris in patients with a normalcoronary angiogram is not clear. Furthermore, the pathophysiologicalimpact of ST changes in syndrome X is controversial. The purposeof this study was to investigate cardiac autonomic function,by measuring 24 h heart rate variability, in patients with andwithout electrocardiographic evidence of ischaemia during exercise. Thirty-two patients with angina pectoris, a normal coronaryangiogram, echocardiogram, hyperventilation test and gastro-oesophagealinvestigation were studied. Fourteen healthy subjects servedas controls. Fifteen patients had significant ST segment depressionduring stress testing, whereas 17 had no electrocardiographicsigns of ischaemia. Heart rate variability was calculated as(1) mean RR= mean of all normal RR intervals, (2) the differencein mean RR level between when awake and when asleep (mean RRwake-sleep)—a tentative index of sympathetic activation,(3) the standard deviation (SD)—a broad band measure ofautonomic balance, and (4) a percentage of successive RR intervaldifferences 6% (pNN6%)—an index of vagal modulation. Thecoronary vascular resistance was measured at rest and duringpacing. Mean RR and autonomic indexes did not differ between patientswith a positive exercise test and controls (831/884 m 24 h SD125/134 m pNN6% 6.715.4%, respectively). Patients with a normalexercise test had shorter mean RR (758 ms vs 844 m P<0.05)and significantly reduced 24-h SD (103 ms vs 134 m P<0.05)than controls, whereas values for vagal index (6.5% vs 5.4%)did not differ from healthy controls. Mean RR wake-sleep alsotended to be lower in patients with a normal exercise test (–125 ms vs – 173 ms) compared to controls (P<0.1). Patientswith a positive exercise test had a significantly attenuatedreduction in coronary vascular resistance during pacing in comparisonto patients with a normal exercise test (–0.131–0.26mmHg x min. ml^{– 1}; P<0.05). The findings suggest the occurrence of general elevated sympatheticactivation in angina patients with a normal exercise test. Patientswith a positive exercise test exhibited no signs of autonomicdysfunction although these patients had altered coronary vascularresistance indicating microvascular angina. This supports thesuggestion that patients with a normal exercise test constitutean independent pathophysiological entity.     

Coronary risk factors in men occupationally exposed to vibration and noise

In a group of 481 men (group A ) exposed occupationally to vibration(exceeding by four times the permissible levels in the frequencyband 32–64–125 Hz) and noise (105–116 dB),and in a group of 303 men without contact with vibration andnoise at work (reference group R) the prevalence of coronaryrisk factors was assessed, Socioeconomic status, level of occupationalphysical activity and family history of heart disease were comparablein the two groups. Mean blood pressure values and the percentage with hypertensionwere significantly higher in the exposed than in the referencegroup(P0.01). Overweight and hypertrigliceridemia occurred lessfrequently in group A than in group R(P0.01 and P0.05 respectively).The prevalence of hypercholesterolaemia and smoking habits wassimilar in both groups. The results suggest that vibration andnoise may be factors which increase the risk of coronary heartdisease.     

Coronary risk factors in men occupationally exposed to vibration and noise

In a group of 481 men (group A ) exposed occupationally to vibration(exceeding by four times the permissible levels in the frequencyband 32–64–125 Hz) and noise (105–116 dB),and in a group of 303 men without contact with vibration andnoise at work (reference group R) the prevalence of coronaryrisk factors was assessed, Socioeconomic status, level of occupationalphysical activity and family history of heart disease were comparablein the two groups. Mean blood pressure values and the percentage with hypertensionwere significantly higher in the exposed than in the referencegroup(P0.01). Overweight and hypertrigliceridemia occurred lessfrequently in group A than in group R(P0.01 and P0.05 respectively).The prevalence of hypercholesterolaemia and smoking habits wassimilar in both groups. The results suggest that vibration andnoise may be factors which increase the risk of coronary heartdisease.     

Correlation between inducibility of sustained ventricular tachycardia and QRS duration

Some studies provide a link between the width of QRS complexesand late potentials occurring at the end of the QRS complexin signal-averaged recordings. The purpose of this study wasto compare three methods of QRS duration measurement: the conventional12 lead ECG. the Frank vectorcardiogram (VCG) and the signal-averagedelectrocardiogram. The recordings were made at a similar timein 121 consecutive patients with the Cardionics PC-based system(ECG and VCG) and the ardionics high resolution ECG, based onmethods described by Simson. Patients with bundle branch blockwere excluded. All patients had presented a myocardial infarctionand were studied either for spontaneous ventricular arrhythmiasor systematically 3 to 6 weeks after an acute myocardial infarction. The signal-averaged ECG and VCG QRS durations were similar in41 patients without inducible ventricular arrhythmias and withnormal signal-averaged ECG but were longer (P<0·001)than the conventional ECG QRS duration. In 36 patients withspontaneous and inducible ventricular tachyarrhythmias, theQRS duration was significantly longer on signal-averaged ECGthan on VCG (P<0·05) and longer on VCG than on conventionalECG (P<0·05). The QRS duration was also significantly(P<0·001) longer with the three techniques in patientswith spontaneous ventricular tachycardia (VT) than in patientswithout spontaneous and inducible VT. A QRS duration on VCG 110 ms and on conventional ECG 100 ms had a sensitivity of93% and 77% and a specificity of 83% and 85% respectively forpredicting an abnormal signal-averaged ECG. In conclusion, the measurement of QRS duration with the conventionalECG, VCG or the signal-averaged ECG could be a simple methodto detect the patients with myocardial infarction prone to VT.     

Spectral turbulence analysis of the signal-averaged electrocardiogram for predicting inducible sustained monomorphic ventricular tachycardia in patients with and without bundle branch block

Spectral turbulence analysis of the signal-averaged electrocardiogramis a new method for identifying patients prone to sustainedmonomorphic ventricular tachycardia. In contrast to analysisin the time domain, it has been claimed to be applicable inpatients with bundle branch block. The aim of this study wasto assess the predictive value of spectral turbulence analysis,in relation to the inducibility of sustained monomorphic ventriculartachycardia, in patients with and without bundle branch block.One hundred and sixty nine patients, of whom 120 had a QRS duration 120 ms, were studied Forty-seven patients had inducible sustainedmononwrphic ventricular tachycardia and were compared to 122control patients. The overall sensitivity of the spectral turbulenceanalysis for predicting inducible ventricular tachycardia was77%, the spectficity 35% and the total predictive accuracy 47%.The limited predictive accuracy was mainly due to a lack ofd between patients with and without ventricular tachycardiain patients with a QRS duration 120 ms. In patients with QRS 120 ms, however, there were significant differences in allspectral turbulence parameters and the method had a sensitivityof 75%, a specificity of 72% and a total predictive accuracyof 73%. The diagnostic usefulness of spectral turbulence analysis isdependent upon normal QRS duration and the method is applicableonly to patients without bundle branch block.     

Effects of amlodipine on transient myocardial ischaemia in patients with a severe coronary condition treated with a beta-blocker

The purpose of this trial was to study the additional anti-ischaemiceffects of amlodipine in coronary patients with ambulant ischaemiadespite beta-blocker therapy. Beta-blockers are the most effectivedrug therapy for reducing the frequency and duration of ambulatoryischaemic episodes. However, the therapeutic advantage of combinedcalcium antagonist-beta-blocker treatment remains questionable. Three hundred and thirteen patients with documented coronaryartery disease, a positive exercise test within 6 months beforeentry and background beta-blocker therapy, were screened. Inclusioncriteria (4 episodes of transient ST segment depression of 1.0 mm and/or 20 min of ischaemia) were demonstrated in a 48h ECG during the placebo run-in period in 84 (25%) of the patients.Eighty-nine percent of the ischaemic episodes were silent. Theeligible patients were then randomized in a 2-week, double-blind,parallel group study comparing placebo to amlodipune 10 mg dailyadded to the beta-blocker. The anti-ischaemic efficacy of thecombination therapy was assessed by 48 h ECG monitoring andexercise tests. Compared to placebo, amlodipine did not significantly reduceeither the frequency (3.7±4.3 vs 4±4.8 episodesin the amlodipune group) or the duration of ambulatory ischaemia(mean duration: 43.9±57.1 vs 39.6±65.7 min, totalduration 3.1±6.7 vs 2.8±6.1 h). Exercise-inducedST segment depression tended to decrease with amlodipine (58%vs 73% in the placebo group) and the ischaemia-free workloadcapacity was increased (+1.7 stage vs 0.7 stage in the placebogroup, P=0.08). These results suggest that 2 weeks treatment with amlodipinemay not provide any additional anti-ischaemic benefit in patientswith ambulant ischaemia resistant to a beta-blocker therapy.     

Protective effect of beta-blockade on dipyridamole-induced myocardial ischaemia: Role of heart rate

This study was designed to investigate the effect of heart ratechanges on dipyridamole echocardiographic tests in patientswith coronary artery disease treated with propranolol. We prospectively studied 12 patients (8 men and 4 women; meanage 56.5 ± 8.7 years) selected by: (a) angiographic evidenceof significant coronary artery disease; (b) adequate echocardiographicwindow; (c) positive dipyridamole echocardiography test resultsin baseline conditions (step I); (d) test reproducibility inthe absence of treatment; (e) negative dipyridamole echocardiographytest results after 7 days of treatment with propranolol (120mg. day^–1) in twice divided doses daily (step II). In all patients treated with propranolol, dipyridamole echocardiographictesting was repeated 24 h after the last negative test. In thesepatients, transoesophageal atrial pacing was performed at peakdipyridamole infusion to increase heart rate to values similarto those observed at baseline (step III). At baseline, heartrate and rate-pressure product were significantly lower in patientstreated with propranolol (–20.3% and –22.5% in groupII, P<0–001 vs step I; –24.3% and –26.4%in group III, P<0.05 vs step I), but the different treatmentsdid not produce significant differences in systolic and diastolicblood pressure. At peak dipyridamole infusion, heart rate andrate-pressure product increased with either placebo or propranololtreatments with respect to baseline, while remaining significantlylower with propranolol as compared to placebo ( –29.6%and –29.5% in step II, P<0001). During treatment withpropranolol plus transoesophageal pacing to maintain heart rateat values attained with placebo, the rate-pressure product didnot change significantly with respect to placebo, nor did systolicblood pressure. Transoesophageal atrial pacing performed duringpropranolol treatment to restore heart rate to baseline valuesdid not affect the dipyridamole echocardiographic test in eightpatients (group I), and induced transient wall abnormalitiesin four patients (group II) (P=ns). Our data suggest that the anti-ischaemic effect of propranololin man is not correlated only to reduction of heart rate.     

Effects of percutaneous balloon mitral valvuloplasty and exercise training on the kinetics of recovery oxygen consumption after exercise in patients with mitral stenosis

Aims Kinetics of recovery oxygen consumption after exercise playsan important role in determining exer-cise capacity. This studywas performed to assess the kinetics of recovery oxygen consumptionin mitral stenosis and evaluate the effects of percutaneousballoon mitral valvuloplasty and exercise training on the kinetics. Methods and Results Thirty patients with mitral stenosis (valve area 1·0cm²)and same sized age- and size-matched healthy volunteers wereincluded for this study. All subjects performed maximal uprightgraded bicycle exercise. Thirty consecutive patients who underwentsuccessful percutaneous balloon mitral valvuloplasty (valvearea 1·5cm²and mitral regurgitation grade 2), were randomizedto an exercise training group or non-training group. The exercisegroup performed daily exercise training for 3 months. Half-recoverytime of peak oxygen consumption was significantly delayed inmitral stenosis as compared to normal subjects (120±42svs 59±5,P<0·01). Peak oxygen consumption (ml.min^–1.kg^–1)was significantly increased in both the training (16·8±4·9to 25·3±6·9) and non-training groups (16·3±5·1to 19·6±6·0) 3 months after percutaneousballoon mitral valvuloplasty. Half-recovery time of peak oxygenconsumption was significantly shortened in the training group(124±39 to 76±13,P<0·01), but not inthe non-training group (114±46 to 109±44s,P=0·12)at 3 months follow-up. The degrees of symptomatic improvementafter percutaneous balloon mitral valvuloplasty were more closelycorrelated with the changes of the half-recovery time of peakoxygen consumption than those of peak oxygen consumption. Conclusion Kinetics of recovery oxygen consumption was markedly delayedin mitral stenosis, which was improved after exercise trainingbut not after percutaneous balloon mitral valvuloplasty alone.These results suggest that adjunctive exercise training maybe useful for improvement of recovery kinetics and subjectivesymptoms after percutaneous balloon mitral valvuloplasty.     

lschaemic heart disease: The QRS score: a promising new exercise score for detecting coronary artery disease based on exercise-induced changes of Q-, R- and S-waves: a relationship with myocardial ischaemia

BACKGROUND: Recently, a new exercise test criterion diagnosing coronaryartery disease was proposed, based on a composite of changesin Q-, R- and S-waves: the QRS score. We compared this new criterionwith conventional ST-segment depression and other compositionsof Q-, R and S-wave changes in patients and normals and relatedthe QRS score to reversible thallium-201 scintigraphic defectsand ST-segment depression as markers for ischaemia. The influenceof beta-blockade on the QRS score was also studied. METHODS: The study population consisted of 155 persons with 53 normals(group I) and 102 patients with documented coronary artery disease(group II). Another 20 patients (group III) with proven coronaryartery disease and a positive exercise test by ST-segment criteriawere studied for the influence of beta-blockade on the QRS score.A symptom-limited exercise protocol according to the modifiedBruce protocol was used. For the QRS score, Q-, R- and S-waveamplitudes which could be recovered immediately were subtractedfrom pretest values: Q, R, S respectively. The score was calculatedby the formula: (R – Q –S)AVF+(R –Q–S)V5. RESULTS: Using a cut-off point of >5 as normal, the QRS score resultedin a sensitivity of 88·2%, a specificity of 84·8%and a predictive accuracy of 87·1%. For ST-segment depressionthese values were 54·9% 83% and 64·5% respectively(P<0·00l compared to the QRS score.) Predictive accuraciesof changes in Q-, R- and S-waves in leads AVF and VS separately,combinations of changes and combining the two leads, resulted—withthe exception of solitary S-wave changes—in predictiveaccuracies higher than those of ST-segment depression, but allwere lower than the QRS score. We found a significant correlationbetween the QRS score, the summed ST-segment depres sion (P<0004)and the extent of reversible thallium-201 defects (P<0·004Applying Bayes' theorem, the combination of an abnormal QRSscore and ST-segment depression resulted in the highest post-testrisk for coronary artery disease and a normal QRS score withoutST-segment depression in the lowest post-test risk. The QRSscore and the maximal ST-segment depression changed significantlyunder the influence of beta-blockade (P<0·02 and P<0·001respectively). CONCLUSION: Our data suggest that an abnormal QRS score reflects myocardialischaemia. Furthermore, for the interpretation of the exercisetest, the combined analysis of ST-segments and the QRS scoreis of value for the prediction of the presence or absence ofcoronary artery disease and its follow-up.