Effects of Nifedipine and Nitroglycerin on Left Ventricular Systolic Dysfunction and Impaired Diastolic Filling After Exercise-Induced Ischemia in Humans

Objectives. This study sought to determine whether calcium antagonist, compared with nitroglycerin, administration attenuates left ventricular dysfunction after exercise-induced ischemia in humans.Background. Exercise-induced ischemia impairs left ventricular systolic function and diastolic filling after exercise. The mechanism of this phenomenon is unknown but may relate to intracellular calcium overload.Methods. Echocardiography was performed in 131 patients before and 30 min, 2 h and 4 h after exercise stress test. Ischemia was defined as a reversible thallium stress defect. No medication, sublingual nitroglycerin or nifedipine was randomly given to each patient at peak exercise.Results. Isovolumetric relaxation time was significantly prolonged from rest (100 ± 19 ms [mean ± SD]) to 30 min (118 ± 20 ms, p < 0.0005), 2 h (117 ± 18 ms, p < 0.0005) and 4 h (110 ± 22 ms, p < 0.05) after exercise in 21 patients with exercise-induced ischemia who received no medication (ischemia-none group). Isovolumetric relaxation time similarly increased after exercise in 23 patients who received nitroglycerin and had exercise-induced ischemia (ischemia-NTG group) but was unchanged in 20 patients with exercise-induced ischemia who received nifedipine (ischemia-nifedipine group). Peak early filling velocity decreased in the ischemia-none and ischemia-NTG groups from rest to 30 min and 2 h after exercise, but peak early filling velocity was unchanged in the ischemia-nifedipine group. Ejection fraction decreased from rest to 30 min after exercise in the ischemia-none group (59 ± 12% vs. 51 ± 13%, p < 0.025) and ischemia-NTG group (59 ± 14% vs. 49 ± 14%, p < 0.005) but was unchanged in the ischemia-nifedipine group (50 ± 19% vs. 64 ± 18%, p = NS). A new regional left ventricular wall motion abnormality occurred more frequently 30 min after exercise in the ischemia-none group (11 [52%] of 21) and ischemia-NTG group (9 [39%] of 23) compared with the ischemia-nifedipine group (2 [10%] of 20, both p < 0.05). No change occurred in left ventricular systolic function and diastolic filling after exercise in the control groups.Conclusions. Exercise-induced ischemia impairs systolic function and diastolic filling after exercise. Sublingual nifedipine but not nitroglycerin attenuates this process and suggests that altered calcium homeostasis may play a role in left ventricular dysfunction that occurs after exercise-induced ischemia.     

Exercise-induced QTc-interval changes for predicting improvement in regional blood flow in ischemic myocardium and cardiac output after coronary angioplasty in patients with right bundle-branch block

BACKGROUND: We have previously shown that QT-interval changes are more useful than ST-T changes in evaluating the severity of exercise-induced myocardial ischemia in patients with right bundle-branch block (RBBB). HYPOTHESIS: The purpose of this study was to evaluate whether the improvement in regional myocardial blood flow (RMBF) in ischemic areas and cardiac output after percutaneous transluminal coronary angioplasty (PTCA) can be predicted by exercise-induced QT-interval changes prior to PTCA. METHODS: The RMBF and cardiac output were quantified with nitrogen-13 ammonia positron emission tomography at rest and during exercise in 20 patients with RBBB and ischemic heart disease before and 6 months after PTCA, and in 9 healthy volunteers. RESULTS: Before PTCA, exercise-induced prolongation by < 20 ms or shortening of the Bazett-corrected QT (QTc) interval (454 +/- 38 to 451 +/- 41 ms, p = NS) was observed in 13 patients (Group 1) and prolongation by > or = 20 ms (429 +/- 44 to 466 +/- 50 ms, p < 0.002) was observed in 7 (Group 2). The number of regions of exercise-induced ischemia was significantly greater in Group 2 than in Group 1 (4.0 +/- 1.2 vs. 2.1 +/- 1.2, p < 0.01). The RMBF in regions of exercise-induced ischemia and cardiac output at rest was not significantly different between Groups 1 and 2, whereas during exercise both the parameters were significantly lower in Group 2 than in Group 1 (both p < 0.05). After successful PTCA, RMBF both at rest and during exercise improved significantly in Group 1 (0.67 +/- 0.04 to 0.71 +/- 0.06 ml/min/g, 0.74 +/- 0.05 to 0.84 +/- 0.08 ml/min/g; both p < 0.0001), but did not improve significantly in Group 2 (0.63 +/- 0.05 to 0.65 +/- 0.07 ml/min/g, 0.65 +/- 0.04 to 0.69 +/- 0.11 ml/ min/g; both p = NS). Cardiac output during exercise improved significantly in Group 1 (6.4 +/- 0.7 to 7.4 +/- 0.9 l/min; p < 0.002) but not in Group 2 (5.7 +/- 0.6 to 5.9 +/- 0.6 l/min; p = NS). CONCLUSIONS: Our results suggest that the marked prolongation of the QTc interval induced by pre-PTCA exercise may predict a lack of improvement in RMBF in ischemic areas and cardiac output after PTCA in patients with RBBB and ischemic heart disease.     

Effects of transluminal coronary angioplasty on left ventricular systolic and diastolic function at rest and during exercise

The left ventricular global and regional systolic function, ventricular volumes, and peak diastolic filling rate (PDFR) were studied in 30 patients with coronary artery disease, before and 2 to 5 days after transluminal coronary angioplasty (PTCA), utilizing equilibrium radionuclide angiography at rest and during exercise. At rest, the global ejection fraction (EF) was unchanged before (60 ± 9%) and after PTCA (62 ± 10%). During exercise, global EF increased from 59 ± 11% pre PTCA to 67 ± 10 post PTCA (p < 0.001). Twenty-two patients had abnormal EF response to exercise pre PTCA, versus seven post PTCA (p < 0.001). Improvements in exercise regional EF paralleled the changes in global EF. End-systolic volume was unchanged at rest but decreased significantly with exercise post PTCA (60 ± 36 ml pre vs 49 ± 32 ml post PTCA, p < 0.01). At rest, the PDFR was unchanged post PTCA (2.4 ± 0.9 end-diastolic volume (EDV)/sec pre vs 2.5 ± 0.8 EDV/sec post). During exercise, PDFR increased from 2.1 ± 0.7 EDV/sec pre PTCA to 2.5 ± 0.7 EDV/sec post PTCA (p < 0.02). In conclusion, in patients with coronary artery disease, successful PTCA improves global and regional systolic function during exercise. Diastolic function is improved during exercise, a fact not previously demonstrated.     

Exercise-induced prolongation of the infarct-related Q-waves as a marker of myocardial viability in the infarcted area

OBJECTIVE: It is known that exercise-induced ischemia in patients with coronary artery disease (CAD) may produce QRS prolongation in the surface electrocardiogram (ECG). To investigate the presence of exercise-induced Q-wave prolongation in patients with single-vessel CAD and Q-wave myocardial infarction (MI), in association with the presence of reversible perfusion defects during thallium scintigraphy in the infarcted area. METHODS: 107 consecutive patients (89 males, mean age 56+/-8 years) were evaluated. All patients underwent coronary arteriography, maximal treadmill exercise testing and thallium-201 scintigraphy. Q-wave duration was measured both before exercise testing and during maximal heart rate from 12-lead ECGs recorded with a paper speed of 50 mm/s. RESULTS: Only 57 out of the 107 studied patients showed reversible perfusion defects in the infarcted area during thallium scintigraphy. Q-wave duration was significantly increased from the resting to the stress ECG (DeltaQ-wave duration) in patients with reversible perfusion defects in the infarcted areas (10+/-13 ms), but not in patients with fixed defects in the infarcted zone (-2.0+/-5 ms, p<0.01). The sensitivities and the specificities of Q-wave prolongation, ST segment elevation, and the combination of ST segment elevation with ST segment depression in the reciprocal leads for the detection of myocardial viability in the infarcted area were 82%, 48%, 29% and 88%, 50%, and 90%, respectively. CONCLUSIONS: Exercise-induced Q-wave prolongation is demonstrated in those patients with single-vessel CAD and a recent MI who show reversible perfusion defects in thallium scintigraphy. Exercise-induced Q-wave prolongation was found to be a sensitive and specific ECG marker for the detection of myocardial viability in the infarcted area.     

The Predictive Value of Exercise QRS Duration Changes for Post‐PTCA Coronary Events

Background: The sensitivity and predictive values of exercise ECG testing using ST‐T criteria after percutaneous transluminal coronary angioplasty (PTCA) are low, precluding its routine use for screening for restenosis. The predictive value of QRS duration criteria during exercise testing (ET) ECG after PTCA for future coronary events has not been reported. The aim of the study was to compare QRS duration changes with ST‐T criteria during ET, as a predictor of coronary events after PTCA. Methods: A prospective study of 206 consecutive patients who underwent ET at a mean of 34 ± 14 days after their first PTCA, and were the followed for a mean of 23 ± 9 months. Patients were divided by QRS duration into two groups—Q1: ischemic response (QRS duration prolongation of more than 3 ms relative to the resting duration), and Q2: normal response (QRS duration shortening or without change from resting duration). Patients were also divided by their ST‐T response, S1: ischemic response, and S2: normal response. Results: During follow‐up 52 patients (58%) experienced restenosis or MI, or underwent CABG—Q1: 44 (85%), Q2: 8(15%) (P < 0.0002), S1: 8 (15%), S2: 44 (85%), (P < 0.641) , two patients died—Q1: 1 (1%) and Q2: 1 (1%). For QRS and ST‐T, the relative risk of having at least one of the coronary events was 4.02 (CI 2.1–9.9) versus 1.13 (CI 0.8–2.9), respectively. The sensitivity for future coronary events was 85% and 52% and the specificity was 48% and 98% for the QRS and ST‐T criteria, respectively. Conclusion: QRS prolongation during peak ET ECG after PTCA is a more sensitive marker than ST‐T criteria for detection of patients at risk for later coronary events.     

QRS Changes During Percutaneous Transluminal Coronary Angioplasty and Their Possible Mechanisms

Objectives. The purpose of the study was to describe the configuration, and investigate the mechanisms, of QRS changes occurring during percutaneous transluminal coronary angioplasty (PTCA).Background. QRS changes during PTCA have been attributed to both a passive ST segment shift and conduction disturbances (peri-ischemic block). The direct relation between ST segment shift and QRS changes, however, has not been established, and the definition of conduction disturbances remains to be clarified.Methods. Twelve-lead electrocardiograms (ECGs) were recorded before PTCA, at the end of 2 min of PTCA and after return to baseline values in 29 patients (left anterior descending coronary artery [LAD] in 13 patients, right coronary artery [RCA] in 14 and left circumflex coronary artery in 2). Electrocardiographic complexes before and during PTCA were superimposed to determine the amplitudes of initial, terminal and total QRS deflection; the relations of QRS changes to baseline (TP segment) and ST segment shift; and the duration of QRS and corrected QT intervals.Results. 1) The direction of the initial QRS deflection was unchanged, but changes of its amplitude occurred. 2) Terminal QRS deflection changed in all patients with a ST segment shift >17% of the R amplitude, and the correlation between the decrease in the S amplitude and ST segment shift was significant (r = 0.9, p < 0.01) in patients with LAD PTCA. Correlation between changes in total QRS amplitude and ST segment shift in patients with RCA PTCA was weaker (r = 0.54, p = 0.056). 3) Transient conduction disturbance manifested by QRS widening in selected leads occurred in 2 of 29 patients.Conclusions. 1) Changes in terminal QRS deflection during PTCA are proportional to the magnitude of the ST segment shift. 2) Conduction disturbances manifested by increased QRS duration occurred infrequently. We suggest that the term peri-ischemic block be applied only to changes in QRS configuration associated with QRS widening.     

QRS波时限延长在冠心病患者运动试验中的意义

目的　探讨冠心病患者运动试验中QRS波时限变化的意义。方法　分析经冠状动脉造影 (冠脉 )证实的6 2例冠心病患者和 16例冠脉造影正常者运动试验前后QRS波时限变化。结果　冠脉正常组运动后QRS波时限较运动前缩短 (P <0 0 5 ) ;冠心病组运动后QRS波时限变化较运动前延长 (P <0 0 1) ;以运动后QRS波时限延长判断为异常 ,诊断冠心病的敏感性为 72 6 % ,特异性为 93 8% ,准确性为97 8%。结论　冠心病患者运动后QRS波时限延长是心肌缺血的一个标志 ,QRS波时限可能是运动试验中诊断冠心病心肌缺血敏感而特异的指标。     

A new screening method to diagnose coronary artery disease using multichannel magnetocardiogram and simple exercise

Background: Magnetocardiography (MCG) is a non-contact mapping technique to record cardiac action currents. The Master's two-step electrocardiogram (ECG) test is a simple exercise method for screening coronary artery disease (CAD), but it is inadequate concerning the sensitivity. Our aim was to develop a new screening method using multichannel MCG instead of ECG. Methods: Thirty subjects (aged 54 ± 16 years, 27 males), 17 of whom had CAD confirmed by coronary angiography, underwent the Master's exercise ECG test. After the exercise, MCG signals were acquired every minute during recovery with a 64-channel MCG system (MC-6400, Hitachi Ltd). We integrated tangential components of the MCG signals within QRS (during 20, 40, 80, and 120 ms centering on R-wave peak) immediately after exercise (Iex) and 5 minutes after exercise (Irec). The exercise-induced change of currents [(Iex-Irec)/Irec] was determined and normalized for each channel, and the maximal change among 64 channels, maximal QRS integral change, was used as a diagnostic index for myocardial ischemia. Results: The maximal QRS integral change during 40 ms was significantly higher in the CAD group than in the control group (0.81 ± 0.51 vs. 0.36 ± 0.19, p < 0.01). A sensitivity and specificity for predicting CAD by the change > 0.44 were 82 % and 85 %, respectively, yielding a diagnostic accuracy of 83 %. The conventional Master's ECG test identified the CAD patients with a diagnostic accuracy of 63 % (sensitivity 47 %, specificity 85 %). Conclusion: The Master's two-step exercise test with a 64-channel MCG system showed the high diagnostic accuracy, despite of non-contact recording and simple exercise. The magnetic field in the depolarization process has the potential to detect the subtle myocardial ischemia induced by exercise. Received: 20 June 2002, Returned for 1. revision: 11 July 2002, 1. Revision received: 3 September 2002, Returned for 2. revision: 25 September 2002, 2. Revision received: 10 October 2002, Accepted: 14 October 2002 Correspondence to: S. Nakatani, MD, PhD     

QRS prolongation: a sensitive marker of ischemia during percutaneous transluminal coronary angioplasty.

The purpose of this study is to measure QRS duration changes in the human model of ischemia during percutaneous transluminal coronary angioplasty (PTCA) and compare these results to the commonly used ischemia markers, chest pain, and classical ST-T changes. Using a computerized method, QRS duration was measured in 51 patients undergoing elective PTCA. Three milliseconds (msec) or more prolongation of the QRS at peak inflation was considered to be an ischemic response. The results were compared to chest pain and ST-T changes and were analyzed for inflation site within individual coronary arteries. Forty-two patients had a pathological prolongation of the QRS during PTCA. Thirty-two patients developed chest pain, while 19 had ischemic ST-T changes. QRS duration was more prolonged in PTCA to proximal or middle segments of major arteries or their large branches, while it was less prolonged in distal segments or smaller branches. Using our method, QRS prolongation was an ischemia marker in most patients during PTCA and was more sensitive than chest pain or ST-T changes. QRS duration was more prolonged with occlusion of proximal and middle segments of major arteries. Cathet. Cardiovasc. Intervent. 50:177-183, 2000.     

Exercise producing alterations in the signal-averaged electrocardiogram in patients after myocardial infarction

Late potentials are considered to be a marker for regional slowconduction which might predispose to reentrant ventricular arrhythmias.Since these arrhythmias may be induced by ischaemia it may bespeculated that exercise-induced myocardial ischaemia may triggerlate potentials. Exercise testing was performed in 53 patients early after myocardialinfarction and in 20 healthy controls. Typical 12 lead ECG andsignal averaged ECG (SA-ECG) from 12 leads were recorded beforeand after exercise testing. Changes in filtered QRS (QRS) andlow amplitude signal durations, and in the root mean squarevoltage of the last 40 ms of the QRS complex (RMS40) were analysed.Tliirty patients developed ST changes, consistent with transientischaemia, that persisted during the SA-ECG recording afterexercise. There were significant differences between baselineSA-ECG and SA-ECG after exercise in patients with positive exercisetests (QRS, 102 ± 15 ms vs 114 ± 15 ms (P<0.01),LAS, 36 ± 12 ms vs 42 ± 11ms (P<0.05), andRMS40, 29± 14µV vs 20 ± 13µV (P<0.01)).No differences were observed in SA-ECG parameters in eitherpatients with negative exercise tests or in controls. During follow-up, four patients died suddenly; all four hadpositive exercise tests and in three of them late potentialswere induced by exercise. We conclude, that in post-infarction patients with positiveexercise tests SA-ECG parameters deteriorate after exercise.This suggests tltat exercise-induced ischaemia triggers developmentof late potentials.     

A QRS score versus ST-segment changes during exercise testing: which is the most reliable ischaemic marker after myocardial revascularisation?

BACKGROUND: The diagnostic ability of exercise testing based on ST-segment changes is low for the detection of restenosis after percutaneous transluminal coronary angioplasty (PTCA) or ischaemia after bypass surgery (CABG). The aim of this study was to improve the diagnostic accuracy of exercise testing in patients with a history of PTCA or CABG, with the implementation of a QRS score. METHODS: We studied 128 post-PTCA patients (aged 49 +/- 8 years) and 104 post-CABG patients (aged 54 +/- 8 years), who had either positive exercise tests with or without angina, or negative exercise tests with continuing angina-like symptoms, and underwent cardiac catheterisation. RESULTS: The univariate risk ratio of exercise-induced ST-segment deviation to detect restenosis was 3.05 (p = 0.005) and 0.83 (p = 0.690) in group A and group B patients, respectively. The univariate risk ratios of abnormal QRS score values to detect restenosis were 32.1 (p < 0.001) and 18.8 (p < 0.001) for group A and group B patients, respectively. The univariate risk ratios of the combination of exercise-induced ST-segment changes and of abnormal QRS score values to detect restenosis was 9.43 (p < 0.001) and 3.77 (p < 0.044) for group A and group B patients, respectively. The value of the area under the ROC curves is higher for the QRS score in group A patients, group B patients and for the whole study population. CONCLUSIONS: QRS score values significantly improve the diagnostic ability of ST-segment change-based exercise testing, for the assessment of restenosis after PTCA or ischaemia after CABG.     

运动试验阴性的男性患者QT离散度的变化对冠心病的诊断价值

目的 观测运动试验中QT离散度的改变是否能够增加运动试验对冠心病的检出率。方法分析60例因有明显的临床指征而行冠状动脉造影的男性患者,术前患者运动试验均未诱发ST段压低。其中34例为两年期间连续冠状动脉造影结果未见显著狭窄者(对照组),26例为两年期间连续冠状动脉狭窄者(实验组)。两组分别测量运动试验前及运动试验后1、3、5分钟12导心电图最长和最短的QT间期的差值,即QT离散度(QTd)。结果 运动停止即刻实验组QTd明显较对照组大。以运动停止即刻QTd大于60ms为指标诊断冠心病的敏感性为84.6％,特异性为76.5％,符合率为87.7％。结论 对运动试验未能诱发出ST段压低的人群。以运动停止即刻QTd大于60ms作为诊断冠心病的指标,可以提高诊断的准确性。     

The diagnostic value of QRS changes for prediction of coronary artery disease during exercise testing in women: false-positive rates

OBJECTIVES: The false positive rate of electrocardiographic exercise testing (ET) for coronary artery disease (CAD) in women ranges from 38 to 67%, using the ST-T changes (ST-T) criteria. The aim of this study was to compare the diagnostic accuracy of QRS duration change criteria with ST-T change criteria during ET. METHODS: We studied 234 women (mean age 58+/-17 years, range 27-83 years), of whom 160 were pre-menopausal (PrMW; mean age 41+/-9, range 27-56) and 74 were post-menopausal (PoMW; mean age 65+/-7, range 57-83). All participants underwent ET to rule out CAD, followed by thallium stress testing (TL). QRS duration, measured with a computerized optical scanner and ST-T changes at peak ET were compared with TL. An ischemic QRS response was defined as an exercise-induced prolongation of QRS duration >3 ms. RESULTS: The sensitivities of QRS duration changes for the entire study group, the PrMW group and the PoMW group in comparison with TL, were 93, 88 and 92%, respectively, while the corresponding rates of specificity were 91, 85 and 91%, respectively. The sensitivities of ET ST-T changes for the entire study group, for the PrMW group and for the PoMW group were 48, 46 and 54%, respectively, while the corresponding rates of specificity were 62, 75 and 79%, respectively. The false-positive rate was 20% for ischemic ST-T and 4% for ischemic QRS duration for the entire study population. CONCLUSIONS: Computer-measured QRS duration changes during ET are more sensitive and specific than ST-T changes for the detection of ischemia in women.     

Reduced delayed rectifier K+ current, altered electrophysiology, and increased ventricular vulnerability in MLP-deficient mice

BackgroundMice with a knockout (KO) of muscle LIM protein (MLP) exhibit many morphologic and clinical features of human cardiomyopathy. In humans, MLP-expression is downregulated both in ischemic and dilative cardiomyopathy. In this study, we investigated the effects of MLP on the electrophysiologic phenotype in vivo and on outward potassium currents.Methods and ResultsMLP-deficient (MLPKO) and wild-type (MLPWT) mice were subjected to long-term electrocardiogram (ECG) recording and in vivo electrophysiologic study. The whole-cell, patch-clamp technique was applied to measure voltage dependent outward K⁺ currents in isolated cardiomyocytes. Long-term ECG revealed a significant prolongation of RR mean (108 ± 9 versus 99 ± 5 ms), P (16 ± 3 versus 14 ± 1 ms), QRS (17 ± 3 versus 13 ± 1 ms), QT (68 ± 8 versus 46 ± 7 ms), QTc (66 ± 6 versus 46 ± 7 ms), JT (51 ± 7 versus 34 ± 7 ms), and JTc (49 ± 5 versus 33 ± 7 ms) in MLPKO versus MLPWT mice (P < .05). During EP study, QT (80 ± 8 versus 58 ± 7 ms), QTc (61 ± 6 versus 45 ± 5 ms), JT (62 ± 9 versus 43 ± 6 ms), and JTc (47 ± 5 versus 34 ± 5 ms) were also significantly prolonged in MLPKO mice (P < .05). Nonsustained VT was inducible in 9/16 MLPKO versus 2/15 MLPWT mice (P < .05). Analysis of outward K⁺ currents in revealed a significantly reduced density of the slowly inactivating outward K⁺ current IK, slow in MLPKO mice (11 ± 5pA/pF versus 18 ± 7pA/pF; P < .05).ConclusionMice with KO of MLP exhibit significant prolongation of atrial and ventricular conduction and an increased ventricular vulnerability. A reduction in repolarizing outward K⁺ currents may be responsible for these alterations.     

Rate-independent QT shortening during exercise in healthy subjects: terminal repolarization does not shorten with exercise

Introduction: QT interval for a given heart rate differs between exercise and recovery (QT hysteresis) due to slow QT adaptation to changes in heart rate. We hypothesized that QT hysteresis is evident within stages of exercise and investigated which component of the QT contributes to hysteresis. Methods and Results: Nineteen healthy volunteers performed a staged exercise test (four stages, 3 min each). Continuous telemetry was analyzed with software to compare QT intervals in a rate‐independent fashion. QRST complexes during each minute were sorted by RR interval, and complexes in bins of 20 ms width were signal‐averaged. QT and QTp (onset of QRS to peak T wave) were measured, and terminal QT calculated (peak to end of T wave, Tpe = QT – QTp). QT, QTp, and Tpe at the same heart rate were compared between the first and last minute of each stage. QT shortened from the first to last minute of exercise in each stage (Stage I: 358 ± 30 to 346 ± 25 ms, P < 0.001; Stage II: 342 ± 27 to 331 ± 24 ms, P = 0.003; Stage III: 329 ± 21 to 322 ± 18 ms, P = 0.03; Stage IV: 313 ± 22 to 303 ± 23 ms, P = 0.005). QTp also shortened in each stage, while Tpe was unchanged. Conclusion: QT hysteresis occurs during exercise in normals, and the major determinant is shortening of the first component of the T wave. Terminal repolarization (peak to end of T wave), a surrogate for transmural dispersion of repolarization, does not shorten significantly with exercise.     

Predictors for permanent pacing after transcatheter aortic valve implantation

Background : Transcatheter aortic valve implantation (TAVI) is a new treatment strategy for patients with symptomatic aortic stenosis who are high risk for traditional surgical aortic valve replacement. The incidence of conduction system abnormalities after the procedure is significant. We examine our experience with CoreValve TAVI focusing on electrocardiographic changes found pre‐, peri‐, and postintervention. Methods : During 2007–08 we undertook 33 cases utilizing the CoreValve revalving system (CoreValve, Paris, France). Assessment of ECGs, with particular reference to the PR and QRS duration, was made daily during each patient's hospital stay. Results : Patients were aged 81.7 ± 6.7 years and the majority were male (57%). Baseline cardiac rhythm was sinus (n = 28, 80%); atrial fibrillation (n = 6, 18%) or ventricular paced (n = 1, 3%). Following CoreValve implantation, prolongation of both the PR interval and QRS duration was seen. Preprocedural PR interval was 193.5 ± 38.7 ms and QRS interval preprocedure was 115.3 ± 24.8 ms. PR interval increased after the procedure by 23.5 ± 23.9 ms and peaked at day 4 with a mean increase of 66.1 ± 72.7 ms. QRS duration increased by a mean of 30.6 ± 26.1 ms postprocedure and remained stable thereafter during the remaining hospital stay. The need for PPM insertion was partially predicted by pre‐procedural QRS morphology: patients with pre‐existing right bundle branch block had an 83% chance of requiring a permanent pacemaker (P < 0.01 OR 28 95%CI 2.4–326.7); those with LBBB had a 33% chance of requiring a pacemaker (P = ns OR 2.3 95%CI 0.2–34.9). Patients undergoing the procedure later in our experience showed a decreased incidence of pacing (P = 0.046 OR 0.36 95% CI 0.07–1.82). Pre‐procedural annulus measurements also predicted the requirement for pacing with larger annulus sizes more likely to require a pacemaker (P = 0.044 OR 3.3 95% CI 0.63–17.6). The requirement for pacing was not predicted by age, baseline PR interval or gender. Requirement for pacing overall was 32% with an additional 13% having had a pacemaker inserted prior to the TAVI. Conclusion : CoreValve insertion was associated with an increase in PR interval and QRS duration. PR interval continued to rise during admission, peaking on Day 4 post procedure, making a prolonged period of monitoring highly desirable. There was a significant requirement for permanent pacing, which was predicted by pre‐procedural QRS morphology, annulus measurement, and the learning curve. © 2010 Wiley‐Liss, Inc.     

Electrocardiographic Markers of Late Sudden Death Risk in Postoperative Tetralogy of Fallot Children

Late Sudden Death Risk in Postoperative TOF. Following surgery for tetralogy of Fallot (TOP), children may develop late onset ventricular arrhythmias. Many patients have both depolarization and repolarization abnormalities, including right bundle branch block (RBBB) and QT prolongation. The goal of this study was to improve prospective risk-assessment screening for late onset sudden death. Resting ECG markers including QRS duration, QTc, JTc, and interlead QT and JT dispersion were statistically analyzed to identify those patients at risk for ventricular arrhythmias and sudden cardiac death. To determine predictive markers for future development of arrhythmia, we examined 101 resting ECGs in patients (age 12 ± 6 years) with postoperative TOF and RBBB, 14 of whom developed late ventricular tachycardia (VT) or sudden death. These ECGs were also compared with an additional control group of 1000 age- and gender-matched normal ECGs. The mean QRS (± SD) in the VT group was 0.18 ± 0.02 seconds versus 0.14 ± 0.02 seconds in the non-VT group (P < 0.01). QTc and JTc in the VT group was 0.53 ± 0.05 seconds and 0.33 ± 0.03 seconds compared with 0.50 ± 0.03 seconds and 0.32 ± 0.03 seconds in the non-VT group (P = NS). There was no increase in QT dispersion among TOF patients with VT or sudden death compared with control patients or TOF patients without VT, although JT dispersion was more common in the TOF groups. A prolonged QRS duration in postoperative TOF with RBBB is more predictive than QTc, JTc, or dispersion indexes for identifying vulnerability to ventricular arrhythmias in this population, while retaining high specificity. The combination of both QRS prolongation and increased JT dispersion had very good positive and negative predictive values. These results suggest that arrhythmogenesis in children following TOF surgery might involve depolarization in addition to repolarization abnormalities. Prospective identification of high-risk children may be accomplished using these ECG criteria.     

Effect of Reperfusion on P‐Wave Duration and P‐Wave Dispersion in Acute Myocardial Infarction: Primary Angioplasty versus Thrombolytic Therapy

Background: Atrial fibrillation (AF) is a common arrhythmia occurring in about 10–20% of patients with acute myocardial infarction (AMI). P‐wave dispersion (PWd) and P‐wave duration (PWD) have been used to evaluate the discontinuous propagation of sinus impulse and the prolongation of atrial conduction time, respectively. This study was conducted to compare the effects of reperfusion either by thrombolytic therapy or primary angioplasty on P‐wave duration and dispersion in patients with acute anterior wall myocardial infarction. Methods: We have evaluated 72 consecutive patients retrospectively (24 women, 48 men; aged 58 ± 12 years) experiencing acute anterior wall myocardial infarction (AMI) for the first time. Patients were grouped according to the reperfusion therapy received (primary angioplasty (PTCA) versus thrombolytic therapy). Left atrial diameter and left ventricular ejection fraction (LVEF) were determined by echocardiography in all patients. Electrocardiography was recorded from all patients on admission and every day during hospitalization. Maximum (P max) and minimum (P min) P‐wave durations and P‐wave dispersions were calculated before and after the treatment. Results: There were not any significant differences between the groups regarding age, gender, left ventricular ejection fraction, left atrial diameter and volume, cardiovascular risk factors, and duration from symptom onset to treatment. P‐wave dispersions and P‐wave durations were significantly decreased after PTCA [Mean P max was 113 ± 11 ms before and 95 ± 17 ms after the treatment (P = 0.007)]. Mean PWd was 46 ± 12 ms before and 29 ± 10 ms after the treatment (P = 0.001). Also, P max and PWd were significantly lower in PTCA group (for P max 97 ± 22 ms vs 114 ± 16 ms and for PWd 31 ± 13 ms vs 55 ± 5 ms, respectively). Conclusions: Primary angioplasty reduces the incidence of AF by decreasing P max and P‐wave dispersion.     

Significance of QRS Duration Changes in the Evaluation of ST‐Segment Depression Presenting Exclusively During the Postexercise Recovery Period

Background: The aim of this study was to evaluate the contribution of QRS prolongation in the diagnosis of coronary artery disease (CAD) in patients with exercise‐induced ST‐segment depression exclusively during the recovery period. Methods: The study population consisted of 107 patients (90 males and 17 females) aged 39–70 (mean 59 ± 7) years who underwent a treadmill exercise test using Bruce protocol and presented ST‐segment depression limited to the recovery period. Angiographic data were available for all studied patients. Results: Among studied patients, 74 (69%) were found to have hemodynamically significant CAD, while the remaining 33 (31%) had normal coronary arteries. Concomitant QRS prolongation was revealed in 61 (82%) of the patients with angiographically documented CAD, while in 13 (18%) patients QRS duration remained unchanged. On the contrary, only 4 (12%) of the 33 patients with normal coronary arteries showed prolonged QRS duration during ST depression, while in the remaining 29 (88%) QRS duration remained unchanged. Conclusions: The evaluation of the concomitant QRS duration changes may discriminate patients with truly ischemia‐induced ST‐segment depression limited to the recovery period.