Prediction of Acute Response to Cardiac Resynchronization Therapy by Means of the Misbalance in Regional Left Ventricular Myocardial Work.

BACKGROUND: Patients with left ventricular (LV) dyssynchrony have a marked misbalance in LV myocardial work distribution, with wasted work in the septum and increased work in the lateral wall. We hypothesized that a low septum-to-lateral wall (SL) myocardial work ratio at baseline predicts acute LV pump function improvement during cardiac resynchronization therapy (CRT). METHODS AND RESULTS: Twenty patients (age 65 ± 10 y, 15 men) underwent cardiac magnetic resonance (CMR) tagging for regional LV circumferential strain assessment and invasive pressure-volume loop assessment at baseline and during biventricular pacing. Segmental work at baseline was calculated from regional strain rate and LV pressure. Subsequently, the SL work ratio was calculated and related to acute pump function (stroke work [SW]) improvement during CRT. During biventricular pacing, SW increased by 33% (P <.001). SL work ratio at baseline was found to be significantly related to SW improvement by means of CRT (R = -0.54; P = .015). Moreover, it proved to be the only marker that was significantly related to acute response to CRT, whereas QRS duration and other measures of dyssynchrony or dyscoordination were not. CONCLUSIONS: The contribution of the septum to LV work varies widely in CRT candidates with left bundle branch block. The lower the septal contribution to myocardial work at baseline, the higher the acute pump function improvement that can be achieved during CRT.

Bifocal left ventricular stimulation or the optimal left ventricular stimulation site in cardiac resynchronization therapy: a pressure-volume loop study.

AIMS: Several implantation strategies have been proposed to improve response to cardiac resynchronization therapy (CRT), including bifocal left ventricular (LV) stimulation and optimal single-LV lead placement. This study aimed to compare these two strategies during invasive pressure-volume (PV) loop measurements. METHODS AND RESULTS: Thirty-three patients eligible for CRT were included [21 (64%) men, 20 (61%) ischaemic aetiology, QRS 155 ± 23 ms], and underwent cardiac magnetic resonance (CMR) imaging and invasive PV loop measurements. Left ventricular pump function was characterized by stroke work (SW) and dP/dtmax (5.1 ± 3.4 L mmHg and 856 ± 190 mmHg/s, respectively). Haemodynamic response was assessed during stimulation at single-LV sites and during bifocal LV [anterolateral and posterolateral (PL)] stimulation. Response during bifocal LV stimulation was not significantly higher compared with standard PL pacing (SW; ß = 9.4 ± 5.4, P = 0.080; dP/dtmax, ß = 0.2 ± 1.9, P = 0.922). However, mean pump function improvement was significantly higher during stimulation at the optimal LV site compared with bifocal LV stimulation (SW; ß = 12.7 ± 5.1, P = 0.012; dP/dtmax, ß = 3.3 ± 1.2, P = 0.020). Myocardial tissue properties were assessed by CMR tissue tagging. Mechanical activation at the optimal LV site was significantly more delayed compared with the worst LV site (431 ± 93 ms vs. 326 ± 127 ms; P = 0.004). CONCLUSION: Stimulation at the optimal LV site showed a significantly higher pump function improvement compared with bifocal LV stimulation. Mechanical activation at the optimal LV site was significantly more delayed compared with the non-optimal LV site. In general, these results suggest that implantation of a second LV lead yields no additional benefit over implantation of one optimally placed LV lead. However, a bifocal approach might be beneficial in the individual patient.

Scar tissue-guided left ventricular lead placement for cardiac resynchronization therapy in patients with ischemic cardiomyopathy: an acute pressure-volume loop study.

BACKGROUND: Response to cardiac resynchronization therapy (CRT) is hampered by the extent and location of left ventricular (LV) scar tissue. It is commonly advised to avoid scar tissue while placing the LV lead. However, whether individual patients benefit from this strategy remains unclear. METHODS: Thirty-two CRT candidates with ischemic cardiomyopathy were enrolled from 2 successive clinical trials (TBS and E-pot study). Magnetic resonance imaging with late contrast enhancement was performed to assess location, degree and transmurality of LV scar tissue. Patients underwent invasive pressure-volume loop measurements to assess acute LV pump function changes during pacing at posterolateral (PL) and anterolateral LV sites. RESULTS: In the study population (26 [81%] men, ejection fraction [EF] 22% ± 8%, QRS 149 ± 20 milliseconds), baseline mean stroke work (SW) and dP/dtmax were 4.4 ± 2.2 L∙mmHg and 849 ± 212 mmHg/s, respectively. The extent of scar tissue was inversely related to the acute increase in SW during pacing (R = -0.53, P = .002). Stimulating PL scar tissue resulted in deterioration of pump function (∆SW -17% ± 17%, P = .018), whereas pacing PL viable tissue led to an increase in pump function (∆SW +62% ± 51%, P < .001). Switching from pacing at the location of scar tissue, irrespective of the scar location, to viable tissue showed a significant increase in SW (-8% ± 20% vs +20 ± 40, P = .004). CONCLUSIONS: The extent of LV scar tissue is inversely related to acute pump function improvement during CRT. Pacing at the location of (transmural) scar tissue at any site of the LV will generally deteriorate LV pump function. Placing the LV lead over viable myocardium significantly improves pump function as compared with pacing at the location of scar tissue in patients with ischemic cardiomyopathy.

Implantable cardioverter-defibrillators have reduced the incidence of resuscitation for out-of-hospital cardiac arrest caused by lethal arrhythmias.

BACKGROUND: Over the last decades, a gradual decrease in ventricular fibrillation (VF) as initial recorded rhythm during resuscitation for out-of-hospital cardiac arrest (OHCA) has been noted. We sought to establish the contribution of implantable cardioverter-defibrillator (ICD) therapy to this decline. METHODS AND RESULTS: Using a prospective database of all OHCA resuscitation in the province North Holland in the Netherlands (Amsterdam Resuscitation Studies [ARREST]), we collected data on all patients in whom resuscitation for OHCA was attempted in 2005-2008. VF OHCA incidence (per 100 000 inhabitants per year) was compared with VF OHCA incidence data during 1995-1997, collected in a similar way. We also collected ICD interrogations of all ICD patients from North Holland and identified all appropriate ICD shocks in 2005-2008; we calculated the number of prevented VF OHCA episodes, considering that only part of the appropriate shocks would result in avoided resuscitation. VF OHCA incidence decreased from 21.1/100 000 in 1995-1997 to 17.4/100 000 in 2005-2008 (P<0.001). Non-VF OHCA increased from 12.2/100 000 to 19.4/100 000 (P<0.001). VF as presenting rhythm declined from 63% to 47%. In 2005-2008, 1972 ICD patients received 977 shocks. Of these shocks, 339 were caused by a life-threatening arrhythmia. We estimate that these 339 shocks have prevented 81 (minimum, 39; maximum, 152) cases of VF OHCA, corresponding with 33% (minimum, 16%; maximum, 63%) of the observed decline in VF OHCA incidence. CONCLUSIONS: The incidence of VF OHCA decreased over the last 10 years in North Holland. ICD therapy explained a decrease of 1.2/100 000 inhabitants per year, corresponding with 33% of the observed decline in VF OHCA.

Electrocardiographic changes in therapeutic hypothermia.

INTRODUCTION: During therapeutic hypothermia (TH), electrocardiographic (ECG) abnormalities such as Osborn waves and/or ST-segment elevation have been described. However, the incidence and prognostic value of these ECG changes are uncertain given the small-scale studies that have been carried out to date. The aim of this study is to further evaluate the electrocardiographic changes during TH. METHODS: During a period of 3 years, 81 patients (age 63 ± 14 years) were included retrospectively. All patients underwent TH after being resuscitated. ECG registrations before, during and after TH were collected and analyzed. Patients were divided into two groups based on the presence or absence of transmural ischemia ST elevation on the first representative ECG upon arrival at the hospital (ST-segment elevation myocardial infarction (STEMI) and non-STEMI). RESULTS: A total of 243 ECGs were analyzed. During TH 24 patients (30%) had Osborn waves, which disappeared in 22 patients (92%) after regaining normal body temperature. The presence of Osborn waves was not associated with age, gender, average pH, electrolytes, or lactate levels and was not associated with excess in-hospital mortality. In 10 patients (12%, six non-STEMI patients) new STEMI was observed during TH, which disappeared after TH discontinuation. The STEMI group (44 patients) had significantly more Osborn waves during TH than the non-STEMI group (38.6% vs. 15.2%, odds ratio = 3.508; 95% confidence interval = 1.281 to 9.610). CONCLUSIONS: Hypothermia-induced Osborn waves are relatively common and are not associated with an unfavorable short-term outcome. TH is associated with ECG changes that may mimic STEMI.

Effects of pacing rates on global and regional myocardial blood flow.

BACKGROUND: Information is scarce on the effects of right ventricular apical (RVA) pacing on regional and global myocardial blood flow (MBF). The purpose of this study was to assess the relationship between pacing rate and both regional and global MBF. METHODS: Four patients with exclusive atrial pacing and six patients with exclusive RVA pacing underwent three consecutive H(2) (15)O positron emission tomography scans at 60, 90, and 130 pulses per minute (ppm). For each pacing rate, regional and global MBF was determined. In all patients, the left ventricular (LV) function was normal. RESULTS: By varying the atrial pacing rate from 60 to 130 ppm, the mean global MBF increased from 0.94 to 1.40 mL/g/min, whereas the mean septal to lateral MBF ratio decreased from 1.09 to 0.83. In ventricular-paced patients at corresponding rates, the mean global MBF also increased from 1.07 to 1.52 mL/g/min but here the mean septal to lateral MBF ratio increased from 0.83 to 1.0. CONCLUSIONS: During both acute atrial and RVA pacing, regional and global MBF increases with higher pacing rates. However, the septal to lateral MBF ratio decreases with atrial pacing and increases with RVA pacing in patients with normal LV function. In RVA pacing, these different rate-dependent effects on regional MBF can be considered as a favorable factor that helps to understand why in some long-term paced patients, LV function is preserved.

Risk stratification for ventricular arrhythmias in ischaemic cardiomyopathy: the value of non-invasive imaging.

The introduction of the implantable cardioverter defibrillator (ICD) has had a major impact on survival and treatment of patients with ischaemic cardiomyopathy. However, only a third of patients receive appropriate ICD discharges during the first 3 years of follow-up, hence creating opportunities for improvement in patient care as well as for health care costs containment. Therefore, refinement of ICD implantation criteria is needed. Evaluation of pathophysiological substrates related to electrical instability with imaging modalities such as nuclear imaging, cardiac magnetic resonance imaging, and echocardiography might yield important prognostic information. This review discusses the currently available literature regarding the value of these imaging modalities for prediction of ventricular arrhythmias in patients with ischaemic cardiomyopathy.

Loss of opposite left ventricular basal and apical rotation predicts acute response to cardiac resynchronization therapy and is associated with long-term reversed remodeling.

BACKGROUND: Normal left ventricular (LV) torsion is caused by opposite basal and apical rotation. Opposite rotation can be lost in heart failure, but might be restored by pacing; therefore, the predictive value of the loss of opposite base-apex rotation in heart failure patients for the response to cardiac resynchronization therapy (CRT) was studied. METHODS AND RESULTS: In 34 CRT candidates and 12 controls, basal and apical LV rotations were calculated using magnetic resonance image tagging. Loss of opposite rotation was quantified by the correlation between both rotation curves: a negative correlation indicates normal, opposite rotation and a positive correlation indicates that base and apex rotate in the same direction. In patients, LV pressure was measured invasively during biventricular stimulation. Acute response to CRT was defined by >10% increase in dP/dt(max) relative to baseline. LV volume was determined at baseline and 8 months follow-up using echocardiography. The base-apex rotation correlation (BARC) was significantly higher in acute responders (n=22) than in nonresponders (n=12) and controls (0.64+/-0.51, -0.23+/-0.67, and -0.68+/-0.22, respectively; P=.001). The sensitivity and specificity for prediction of acute response were 82% and 83%, respectively, at a cutoff value of 0.5. At follow-up, volumes could be analyzed in 18 patients. In the group with BARC >0.5, end-diastolic volume decreased by 7% (NS), end-systolic volume by 16%, and ejection fraction increased by 28% (both P=.02), whereas in the group with BARC <0.5, no significant changes were observed. CONCLUSIONS: The loss of opposite base-apex rotation in patients eligible for CRT is an excellent predictor of acute response and is associated with LV reverse remodeling.

Stroke work or systolic dP/dtmax to evaluate acute response to cardiac resynchronization therapy: are they interchangeable?

BACKGROUND: Cardiac resynchronization therapy (CRT) is characterized by a approximately 30% non-response. Invasive haemodynamic measurements are a traditional method to evaluate response to CRT. This study evaluates the correlation between acute changes in dP/dt(max) and Stroke Work (SW) during CRT. METHODS: Thirty-four CRT candidates were haemodynamically evaluated by pressure-volume loop analysis during biventricular pacing. RESULTS: Mean dP/dt(max) and SW at baseline were 854 +/- 198 and 5186 +/- 2349, and displayed an increase during pacing of 106 +/- 117 mmHg/s (13% +/- 14%) and 1303 +/- 3039 mL/mmHg (30% +/- 52%), respectively. No correlation was found between the percentage change in dP/dt(max) and SW (R = 0.06, P = ns). When defining response an augmentation of 10% relative to baseline for both parameters, 16 patients demonstrated an ambiguous response. CONCLUSION: Although both parameters display an average increase during pacing, the change relative to baseline values of SW and dP/dt(max) is not related.

Usefulness of a pacing guidewire to facilitate left ventricular lead implantation in cardiac resynchronization therapy.

BACKGROUND: Intraoperative measurements of left ventricular (LV) pacing and sensing values were assessed using a novel 0.014-inch guidewire (Visionwire, Biotronik GmbH, Berlin, Germany) enabling pacing and sensing at the distal tip before final LV lead implantation. METHODS: Twenty-two consecutive patients selected for cardiac resynchronization therapy were studied. RESULTS: Significant correlation was found between the LV pacing threshold as assessed by the Visionwire and values after final LV lead implantation (r = 0.92, P < 0.001). Correlation for LV sensing was also significant (r = 0.72, P < 0.001). No significant correlation was present with respect to phrenic nerve stimulation. However, no phrenic nerve stimulation at 10 V/0.5 ms using the Visionwire identified 88% of patients without phrenic nerve stimulation at 10 V/0.5 ms with subsequent LV lead measurements. CONCLUSION: This technique may facilitate transvenous LV lead implantation by preventing implantation in a unsuitable target vessel with respect to pacing and sensing values or phrenic nerve stimulation, thereby reducing procedure and fluoroscopy time.

Effects of breath-holding position on the QRS amplitudes in the routine electrocardiogram.

BACKGROUND: The effects of different breath-holding positions during electrocardiographic (ECG) recording on the QRS complex are unknown. METHODS: In 73 subjects, ECG recordings were made in 3 different breath-holding positions: normal expiration (rest), maximum inspiration, and maximum expiration. QRS wave excursions and changes in the frontal electrical heart axis were analyzed. RESULTS: The mean effect of respiration in most leads was small (> or =1 mm only in the S wave in V(4) and in the R wave in V(5)), but the degree of interindividual variability was often substantial, with standard deviations of > or =1.5 mm in multiple leads. CONCLUSION: The effect of different extreme breath-holding positions on the QRS complex is on average small but may be substantial in individuals. Lack of standardization of breathing instructions during recording of the ECG may result in differences in application of amplitude criteria and poorer reproducibility.

High dose adenosine for suboptimal myocardial reperfusion after primary PCI: A randomized placebo-controlled pilot study.

OBJECTIVES: This study was designed to investigate the influence of high dose intracoronary adenosine on persistent ST-segment elevation after primary percutaneous coronary intervention (PCI). BACKGROUND: After successful PCI for acute myocardial infarction 40-50% of patients show persistent ST-segment elevation indicating suboptimal myocardial reperfusion. Adenosine has been studied to ameliorate reperfusion and is frequently used in a variety of doses, but there are no prospective studies to support its use for treatment of suboptimal reperfusion. METHODS: We conducted a blinded, randomized, and placebo-controlled study with high dose intracoronary adenosine in 51 patients with <70% ST-segment resolution (STRes) after successful primary PCI. All patients were treated with stents and abciximab. RESULTS: Immediately after adenosine, significantly more patients showed optimal (>70%) STRes compared with placebo (33% versus 9%, P < 0.05). Mean STRes was higher after adenosine (35.4% versus 23.0%, P < 0.05). In addition, TIMI frame count was significant lower (15.7 versus 30.2, P < 0.005), Myocardial Blush Grade was higher (2.7 versus 2.0, P < 0.05) and resistance index was lower in the adenosine group (0.70 versus 1.31 mm Hg per ml/min, P < 0.005). CONCLUSIONS: Intracoronary adenosine accelerates recovery of microvascular perfusion in case of persistent ST segment elevation after primary PCI.

Recurrent ventricular fibrillation caused by coronary artery spasm leading to implantable cardioverter defibrillator implantation.

Coronary artery spasm has been known to induce ischaemia and ventricular arrhythmias. We present a case of recurrent ventricular fibrillation caused by spasm-associated transmural myocardial ischaemia. During an intra-coronary acetylcholine provocation test, severe coronary spasm could be induced. The patient was treated with a hybrid approach of medication and an implantable defibrillator.

Low dose oral haloperidol does not prolong QTc interval in older acutely hospitalised adults: a subanalysis of a randomised double-blind placebo-controlled study.

BACKGROUND: Haloperidol is the most frequently prescribed antipsychotic for delirium symptoms. The risk of QTc prolongation often raises concerns, although the effect of haloperidol on QTc interval has not yet been investigated in a randomised placebo-controlled fixed-dose study. METHODS: A subanalysis of a randomised double-blind placebo-controlled study was conducted to evaluate the effect of prophylactic haloperidol 1 mg or placebo 1 mg orally twice-daily (maximum of 14 doses) on QTc interval in patients aged 70 years and over. Bedside, 12-lead ECGs were recorded before, during and after the one-week intervention period. Automatic QTc measurements were obtained in addition to manual measurements of QT and RR intervals, blinded for treatment status. Manual measurements were corrected (QTc) using Bazett (QTc-B), Framingham (QTc-Fa), Fridericia (QTc-Fi) and Hodges (QTc-H) methods. Mixed model analyses were used to test for differences in longitudinal course of QTc between patients receiving haloperidol and placebo. RESULTS: ECG recordings of 72 patients (haloperidol n = 38) were analysed, 45.8% male. Median (range) haloperidol serum concentration on day 4 was 0.71 (0.32-1.82) µg/L (n = 23). Longitudinal course of mean QTc did not significantly differ between treatment arms for any of the automatic or manually derived QTc values. CONCLUSIONS: Low dose oral haloperidol did not result in QTc prolongation in older acutely hospitalised patients. Results may not be generalizable to patients with existing ECG abnormalities such as atrial fibrillation.

Nationwide Longitudinal Follow-Up of Riata Leads Under Advisory at 3 Annual Screenings: Report From the Netherlands Heart Rhythm Association Device Advisory Committee.

OBJECTIVES: This study sought to determine prospectively the rate of conductor externalization (CE), and whether this was associated with electrical failure. BACKGROUND: The Riata family of defibrillator leads was placed under U.S. Food and Drug Administration advisory as of November 28, 2011 because of high rates of CE. METHODS: A nationwide cohort established in 2012 of 1,029 patients with recalled Riata leads with 147 CE were followed until death, lead discontinuation, or 3 annual screenings with fluoroscopy and device interrogation. RESULTS: Follow-up of 882 patients with normal baseline fluoroscopy revealed incident overt CE in 95 leads (11%) after median risk time of 2.9 years, yielding an incidence rate of 4.9 (95% confidence interval [CI]: 3.9 to 5.9) per 100 patient-years. The incidence rate was significantly higher in 8-F Riata leads than in 7-F Riata ST leads (7.0 vs. 3.2 per 100 patient-years; p < 0.001). Electrical follow-up demonstrated electrical abnormality in 77 leads, resulting in an incidence rate of 4.0 (95% CI: 3.2 to 5.0) per 100 patient-years. The incidence rate of electrical abnormalities was not different between leads without CE and those with CE (3.9 vs. 5.2 per 100 patient-years; p = 0.39). CONCLUSIONS: The development of CE is progressive in nature with an incidence rate of new CE of 4.9 per 100 patient-years, with a higher rate for 8-F Riata leads than for 7-F Riata ST leads. Despite the high rate of structural failure, no association between development of CE and electrical failure was observed.

Effects of cardiac resynchronization therapy on myocardial perfusion reserve.

BACKGROUND: Cardiac resynchronization therapy (CRT) is a relatively new treatment strategy for patients with heart failure and mechanical asynchrony. Reported effects of CRT on regional myocardial blood flow (MBF) are conflicting, and effects on hyperemic MBF are scarce. The aim of the present study was to assess serial changes of MBF and MBF reserve in patients receiving a biventricular pacemaker. METHODS AND RESULTS: Fourteen patients with heart failure (NYHA class III or IV; left ventricular ejection fraction <35%), QRS width >120 ms, and sinus rhythm were studied (mean age, 58+/-10 years; 8 men). MBF and hyperemic MBF were measured at baseline, 3 months after biventricular pacing (CRT on), and after cessation of pacing (CRT off) with PET and H2(15)O. CRT had no significant effect on resting MBF (baseline versus CRT on versus CRT off: 0.82+/-0.25 versus 0.69+/-0.24 versus 0.74+/-0.24 mL x min(-1) x mL(-1); P=NS). Hyperemic MBF increased during CRT (1.91+/-1.03 versus 2.66+/-1.66 versus 1.92+/-1.06 mL x min(-1) x mL(-1); P=0.01 by MANOVA), as did MBF reserve (2.25+/-1.00 versus 3.76+/-2.38 versus 2.49+/-0.94 mL x min(-1) x mL(-1); P=0.023). CRT (reversibly) resulted in a more homogeneous distribution of regional resting MBF as demonstrated by the septal-to-lateral ratio. The decrease in the ratio of left ventricular end-diastolic volume to left ventricular mass, as a reflection of wall stress, was related to the increase in hyperemic MBF (r=0.53, P<0.05). Left ventricular ejection fraction increased from 25+/-7% to 37+/-9% (P<0.01). CONCLUSIONS: Resting MBF is unaltered by CRT despite an increase in left ventricular function. However, the distribution pattern of resting MBF becomes more homogeneous. Hyperemic MBF and consequently MBF reserve are enhanced by CRT.

Repeated assessment of coronary flow velocity pattern in patients with first acute myocardial infarction.

OBJECTIVES: The aim of this study was to evaluate the coronary blood flow velocity pattern immediately and 24 h after percutaneous transluminal coronary angioplasty (PTCA) for acute myocardial infarction (AMI) in relation to myocardial reperfusion and follow-up left ventricular (LV) function. BACKGROUND: Analysis of coronary blood flow velocity pattern after AMI may provide information about microvascular damage and the occurrence of a reperfusion injury. METHODS: Measurement of coronary blood flow velocity pattern was performed immediately after PTCA and after 24 h in 25 patients with first AMI using a Doppler guidewire. Measurements were related to reperfusion determined by intravenous myocardial contrast echocardiography (MCE) performed before PTCA and at 24 h and to LV function at four weeks. RESULTS: Using MCE, 13 patients showed reperfusion and 12 patients showed nonreperfusion. Compared with patients with reperfusion, patients with MCE nonreperfusion had a lower systolic peak flow velocity immediately after PTCA (10.0 +/- 0.3 cm/s vs. 19.3 +/- 0.8 cm/s, respectively) and after 24 h (12.3 +/- 0.4 cm/s vs. 21.3 +/- 0.1 cm/s, respectively, p = 0.0022), more frequent early systolic retrograde flow (6/12 vs. 0/13, p = 0.0052 immediately after PTCA and 24 h later) and a shorter diastolic deceleration time immediately after PTCA (483 +/- 6 ms vs. 737 +/- 0 ms, respectively) and after 24 h (551 +/- 9 ms vs. 823 +/- 2 ms, respectively, p = 0.0091). Similarly, patients with impaired LV function at four weeks had altered coronary flow pattern compared with patients with preserved function. The coronary flow velocity pattern showed a tendency for improvement after 24 h in the reperfusion and the nonreperfusion groups. CONCLUSIONS: The coronary flow velocity pattern immediately and 24 h after PTCA for AMI relates to myocardial perfusion determined by MCE and LV function at four weeks. The flow velocity pattern shows slight improvement during the first 24 h after revascularization, indicating the absence of a major reperfusion injury.

Prognostic value of coronary blood flow velocity and myocardial perfusion in intermediate coronary narrowings and multivessel disease.

OBJECTIVES: This study aimed to investigate the roles of intracoronary derived coronary flow velocity reserve (CFVR) and myocardial perfusion scintigraphy (single photon emission computed tomography, or SPECT) for management of an intermediate lesion in patients with multivessel coronary artery disease. BACKGROUND: Evaluation of the functional significance of intermediate coronary narrowings (40% to 70% diameter stenosis) is important for clinical decision making and risk stratification. METHODS: In a prospective, multicenter study, SPECT was performed in 191 patients with stable angina and multivessel disease and scheduled for angioplasty (percutaneous transluminal coronary angioplasty, or PTCA) of a severe coronary narrowing. Coronary flow velocity reserve was determined selectively distal to an intermediate lesion in another artery using a Doppler guidewire. Percutaneous transluminal coronary angioplasty of the intermediate lesion was deferred when SPECT was negative or CFVR greater-than-or-equal 2.0. Patients were followed for one year to document major cardiac events (death, infarction, revascularization), related to the intermediate lesion. RESULTS: Reversible perfusion defects were documented in the area of the intermediate lesion in 30 (16%) patients; CFVR was positive in 46 (24%) patients. Percutaneous transluminal coronary angioplasty of the intermediate lesion was deferred in 182 patients. During follow-up, 19 events occurred (3 myocardial infarctions, 16 revascularizations). Coronary flow velocity reserve was a more accurate predictor of cardiac events than was SPECT; relative risk: CFVR 3.9 (1.7 to 9.1), p < 0.05; SPECT 0.5 (0.1 to 3.2), p = NS. Multivariate analysis revealed CFVR as the only significant predictor for cardiac events. CONCLUSIONS: Deferral of PTCA of intermediate lesions in multivessel disease is safe when CFVR greater-than-or-equal 2.0 (event rate 6%). This selective evaluation of coronary lesion severity during cardiac catheterization allows a more accurate risk stratification than does SPECT, which is important for clinical decision making in this patient cohort.

Perfusable tissue index as a potential marker of fibrosis in patients with idiopathic dilated cardiomyopathy.

UNLABELLED: A varying degree of interstitial and perivascular fibrosis is a common finding in idiopathic dilated cardiomyopathy (DCM). The perfusable tissue index (PTI), obtained with PET, is a noninvasive tool for assessing myocardial fibrosis on a regional level. Measurements of the PTI in DCM, however, have not been performed yet. This study was undertaken to test the hypothesis that the PTI is reduced in patients with DCM. METHODS: Fifteen patients with an advanced stage of DCM (New York Heart Association class III or IV and left ventricular ejection fraction [LVEF] < 35%) and 11 healthy control subjects were studied. PET was performed using H(2)(15)O and C(15)O to obtain the perfusable tissue fraction (PTF) and the anatomic tissue fraction (ATF), respectively. RESULTS: The PTI (=PTF/ATF) was reduced in DCM compared with control subjects (0.91 +/- 0.12 vs. 1.12 +/- 0.10; P < 0.01). Heterogeneity of the PTI, expressed as the coefficient of variation, was increased in DCM versus that of healthy control subjects (0.18 +/- 0.07 vs. 0.13 +/- 0.06; P < 0.05). There was no correlation between the PTI and echocardiographically derived LVEF in both groups. CONCLUSION: The PTI was reduced in patients with an advanced stage of DCM. Interstitial and perivascular fibrosis may be responsible for this reduction. Furthermore, the degree of the PTI reduction was variable in DCM patients, both on a regional level and between patients. Noninvasive assessment of fibrosis with the PTI offers the opportunity to evaluate the effects of fibrosis on regional myocardial function, correlate fibrosis with prognosis, and monitor pharmaceutical intervention.

Noninvasive mapping of left ventricular electromechanical asynchrony by three-dimensional echocardiography and semi-automatic contour detection.

A system for analyzing left ventricular (LV) electromechanical asynchrony based on transesophageal 3-dimensional echocardiography (3-DE) and semi-automatic endocardial contour detection is described. Eighteen consecutive patients underwent 3-DE. Using TomTec 4DLV software, a 3-dimensional endocardial surface was reconstructed throughout the cardiac cycle. Matlab software generated color-coded polar maps, displaying regional LV displacement and its timing. At the segmental level, Bland-Altmann assessment showed intraobserver variability of LV displacement of 0.1 +/- 3.0 mm and timing of -5.6 +/- 160 ms (bias +/- 2 SD) for all segments and -1.6 +/- 94 ms for the nonapical segments. The combination of 3-DE and semi-automatic contour detection is feasible and provides unique information for assessing regional LV endocardial displacement and electromechanical asynchrony.