Stavros I. Chrysostomakis

Myocardial perfusion in patients with permanent ventricular pacing and normal coronary arteries

OBJECTIVES The purposes of this study were to test the specificity of dipyridamole myocardial perfusion scintigraphy in patients with permanent ventricular pacing (PVP) and to evaluate coronary blood flow and reserve in these patients. BACKGROUND Permanent ventricular pacing is associated with exercise perfusion defects on myocardial scintigraphy in the absence of coronary artery disease (CAD). On the basis of studies in patients with left bundle brunch block, coronary vasodilation with dipyridamole has been proposed as an alternative to exercise testing for detecting CAD in paced patients, but this approach has never been tested. METHODS Fourteen patients with a PVP and normal coronary arteries underwent stress thallium-201 scintigraphy and cardiac catheterization. In these patients and in eight control subjects, coronary flow velocities were measured in the left anterior descending coronary artery (LAD) and in the dominant coronary artery before and after adenosine administration. RESULTS In the paced patients, coronary flow velocities in the LAD and in the dominant coronary artery were significantly lower than those in the control subjects. In addition, seven patients showed perfusion defects on dipyridamole thallium-201 single-photon emission computed tomography, with a specificity of 50% for this test. The defect-related artery in these patients had lower coronary flow reserve (2.6 +/- 0.5) as compared with those without perfusion defects (3.9 +/- 1.0, p < 0.05) or the control group (3.5 +/- 0.5, p < 0.05). CONCLUSIONS Permanent ventricular pacing is associated with alterations in regional myocardial perfusion. Furthermore, abnormalities of microvascular flow, as indicated by reduced coronary flow reserve in the defect-related artery, are at least partially responsible for the uncertain specificity of dipyridamole myocardial perfusion scintigraphy.

Sleep patterns in patients with acute coronary syndromes

BACKGROUND Little is known about sleep quality in patients with acute coronary syndromes (ACS) admitted to the coronary care unit (CCU). The aim of this study was to assess nocturnal sleep in these patients, away from the CCU environment, and to evaluate potential connections with the disease process. METHODS Twenty-two patients with first ever ACS, who were not on sedation or inotropes, underwent a full-night polysomnography (PSG) in our sleep disorders unit within 3 days of the ACS and follow-up PSGs 1 and 6 months later. RESULTS PSG parameters showed a progressive improvement over the study period. There was a statistically significant increase in total sleep time (TST), sleep efficiency, slow wave sleep (SWS), and rapid eye movement (REM) sleep, while arousal index, wake after sleep onset (WASO) and sleep latency decreased. Six months after the acute event, sleep architecture was within the normal range. CONCLUSIONS Patients with ACS have marked alterations in sleep macro- and micro-architecture, which have a negative influence on sleep quality. The changes tend to disappear over time, suggesting a relationship with the acute phase of the underlying disease.

Amiodarone, Sotalol, or Propafenone in Atrial Fibrillation: Which Is Preferred to Maintain Normal Sinus Rhythm?

This randomized study compared the efficacy and safety of amiodarone, propafenone and sotalol in the prevention of atrial fibrillation. Methods: The population consisted of 214 consecutive patients (mean age 64 ± 8 years, 106 men) with recurrent symptomatic atrial fibrillation. After restoration of sinus rhythm, patients were randomized to amiodarone (200 mg/day), propafenone (450 mg/day) or sotalol (320 ± 20 mg/day). Follow‐up evaluations were conducted at 1, 2, 4 and 6 months, and at 3‐month intervals thereafter. The proportion of patients developing recurrent atrial fibrillation and/or experiencing unacceptable adverse effects was measured in the three groups by the Kaplan‐Meier method. Results: Recurrent atrial fibrillation occurred in 25 of the 75 patients treated with amiodarone compared to 51 of the 75 patients treated with sotalol and 24 of the 64 patients treated with propafenone. Fourteen patients treated with amiodarone, five with sotalol, and one with propafenone experienced adverse effects while in sinus rhythm, necessitating discontinuation of treatment (P < 0.001 for amiodarone and propafenone vs sotalol). The difference between amiodarone and propafenone was statistically nonsignificant when all events were included in the analysis. However, if the analysis was limited to recurrent atrial fibrillation events, amiodarone was more effective than propafenone (P < 0.05). Conclusions: Amiodarone and propafenone were superior to sotalol in maintaining long‐term normal sinus rhythm in patients with atrial fibrillation. Amiodarone tended to be superior to propafenone, though its long‐term efficacy was limited by adverse side effects.

AAIR Versus DDDR Pacing in Patients with Impaired Sinus Node Chronotropy: An Echocardiographic and Cardiopulmonary Study

The aim of this study was to compare AAIR and DDDR pacing at rest and during exercise. We studied 15 patients (10 men, age 65 ± 6 years) who had been paced for at least 3 months with activity sensor rate modulated dual chamber pacemakers. All had sick sinus syndrome (SSS) with impaired sinus node chronotropy. The patients underwent a resting echocardiographic evaluation of systolic and diastolic LV function at 60 beats/min during AAIR and DDDR pacing with an AV delay, which ensured complete ventricular activation capture. Cardiac output (CO) was also measured during pacing at 100 beats/min in both pacing modes. Subsequently, the oxygen consumption (VO2at) and VO2at pulse at the anaerobic threshold were measured during exercise in AAIR mode and in DDDR mode with an AV delay of 120 ms. The indices of diastolic function showed no significant differences between the two pacing modes, except for patients with a stimulus‐R interval > 220 ms, for whom the time velocity integral of LV filling and LV inflow time were significantly lower under AAI than under DDD pacing. At 60 beats/min, CO was higher under AAI than under DDD mode only when the stimulus‐R interval was below 220 ms. For stimulus‐R intervals longer than 220 ms, and also during pacing at 100 beats/min, the CO was higher in DDD mode. The stimulus‐R interval decreased in all patients during exercise. The time to anaerobic threshold, VO2at ond VO2at pulse showed no significant differences between the two pacing modes. Our results indicate that, at rest, although AAIR pacing does not improve diastolic function in patients with SSS, it maintains a higher CO than does DDDR pacing in cases where the stimulus‐R interval is not excessively prolonged. On exertion, the two pacing modes appear to be equally effective, at least in cases where the stimulus‐R interval decreases in AAIR mode.

Autonomic nervous system changes in vasovagal syncope: is there any difference between young and older patients?

Spectral analysis of heart rate variability was used to compare the changes in autonomic function during tilting in young and older patients with vasovagal syncope. Twenty‐four young (age 28 ± 8 years) and 31 older (56 ± 5 years) patients with unexplained syncope and a positive tilt test and 25 controls (age 48 ± 12 years) were included in the study. Frequency‐domain measurements of the low (LF) (0.06–0.15 Hz) and high (HF) (0.15–0.40 Hz) frequency bands and the ratio of LF to HF were computed from Holter recordings for 4‐minute intervals before and immediately after tilting and just before the end in all groups. Syncopal patients showed a different pattern of response to tilting from controls in all spectral indexes. Young and older patients showed the same pattern of changes in all measurements, even though certain differences were observed. The LF after tilting reduced more in the older (‐20 ± 7% vs ‐14 ± 5%, P < 0.001), while HF reduced more in young patients (‐17 ± 8% vs ‐8 ± 3%, P < 0.001). Young patients showed mainly a cardioinhibitory type (71%) of response whereas a vasodepressor type response predominated (68%) in the older patients. The autonomic nervous system appears to play an important role in the pathophysiological mechanism of vasovagal syncope. This role is similar in young and in older patients and this should be taken into account in the therapeutic approach to the condition. Specific differences between age groups may be related to the type of vasovagal syncope.

Reproducibility of Time-Domain Indexes of Heart Rate Variability in Patients With Vasovagal Syncope

The aim of this study was to examine whether the indexes of heart rate variability (HRV) are stable from day-to-day in patients with vasovagal syncope and whether the stability of the HRV indexes is linked with that of the clinical results of the tilt test. Nineteen patients with a history of syncopal episodes and a positive tilt test underwent a second test 1 week later. Of these, 11 (group P-P) also had a positive second test, whereas 8 (group P-N) had a negative second test. Fifteen healthy volunteers served as a control group. Five time domain indexes were derived: the mean of all coupling intervals between normal beats (mean NN), the SD about the mean of all coupling intervals between normal beats (SDNN), the mean of all 5-minute standard deviations of NNs (SD), the proportion of adjacent normal RR intervals differing by >50 ms (pNN50), the root-mean-square of the difference between successive RRs (rMSSD) and the standard deviations of 5-minute mean NN intervals (SDANN). The control group showed good reproducibility of all HRV indexes (slope 0.86 to 0.97). The syncopal patients taken as a whole had significantly less reproducibility than the controls in the pNN50 parameter. This difference was due entirely to the patients in the P-N group, who had a remarkable lack of reproducibility in both the pNN50 and rMSSD measures (slope pNN50, 0.52; rMSSD, 0.78), whereas the P-P group had a reproducibility of all HRV indexes, which was no different from that in controls (slope 0.83 to 1.04). In patients with vasovagal syncope, certain HRV measures that express parasympathetic tone did not show the high reproducibility found in normal subjects. Syncopal patients who lack reproducibility in these HRV parameters also show a lack of reproducibility in the clinical result of tilt testing.

Is There Increased Sympathetic Activity in Patients with Mitral Valve Prolapse

The aim of this study was to investigate autonomic nervous system tone in patients with mitral valve prolapse (MVP). Heart rate variability (HRV) was assessed from 24‐hour ambulatory Holter recordings in 28 patients with primary MVP and in 28 age and sex matched normal control subjects in a drug‐free state. Sixteen of the MVP patients were symptomatic and 12 asymptomatic. Spectral HRV was calculated in terms of low (LF: 0.06–0.15 Hz) and high (HF: 0.15–0.40 Hz) frequency components using fast Fourier transform analysis, and the ratio LF/HF was calculated. Spectral analysis of HRV showed that the MVP patients, taken as a single group, had lower HF and LF and a higher LF/HF ratio than the controls. No significant difference in HRV was found between the 16 symptomatic and the 12 asymptomatic patients, but the symptomatic patients had a significantly higher LF/HF ratio than the controls. Our observations suggest that, during normal daily activities, patients with MVP experience a significant deviation in autonomic nervous system tone with predominance of the sympathetic branch. This predominance is more marked in symptomatic patients.

Angiotensin II Type 1 Receptor Inhibition is Associated with Reduced Tachyarrhythmia-Induced Ventricular Interstitial Fibrosis in a Goat Atrial Fibrillation Model

BackgroundUsing a goat animal model, we tested the hypothesis that angiotensin-II inhibition reduces fibrotic degeneration of both the atrial and ventricular myocardium as well as AF induction susceptibility.MethodsWe studied three groups of five goats over a 6-month period. The study animals in the first two groups were implanted with a pacemaker capable of maintaining AF with burst pacing. Additionally, in one group, goats were administered candesartan (AF+candesartan group). The third group (SR group) of animals served as control. Animals were tested for AF induction on day 0, 1, 30, 90 and 180. A “Vulnerability Index” (VI) for AF induction was calculated, defined as the ratio of total time in AF per number of bursts needed to induce sustained AF, in each session. At the end of the study, all four heart chambers were examined and fibrosis quantified.ResultsBoth AF goat groups developed cardiomegaly due to tachy-cardiomyopathy. Although, the VI was significantly increased in AF group over time (28.8 ± 43 to 284.7 ± 291, p = 0.045), this was not the case for AF+candesartan group (30.3 ± 40 to 170.8 ± 243, p = 0.23). Histology revealed a significant increase of fibrous tissue in goats with induced AF, noticeable in all four heart chambers, compared to controls. However, the degree of fibrosis was significantly lower in AF animals on candesartan.ConclusionsOur study demonstrated a beneficial effect of angiotensin II inhibition on tachyarrhythmia-induced ventricular fibrosis. It is also consistent with previous studies indicating a reduction in burst-induced AF susceptibility in goats and confirms the favorable effects in atrial structural remodeling.

Electrocardiographic appearance of old myocardial infarction in paced patients.

KOCHIADAKIS, G.E., et al.: Electrocardiographic Appearance of Old Myocardial Infarction in Paced Patients. This study evaluated the possibility of diagnosing chronic myocardial infarction in the presence of the pacing electrocardiogram. Forty‐five patients with known myocardial infarction (anterior 23, inferior 22) and 26 healthy controls were studied. After coronary angiography, pacing was applied from the right ventricular apex, and the sensitivity, specificity, and average diagnostic accuracy of five criteria on the paced electrocardiogram were assessed: (1) Notching 0.04 second in duration in the ascending limb of the S wave of leads V3, V4, or V5 (Cabreras sign); (2) Notching of the upstroke of the R wave in leads I, aVL, or V6 (Chapmans sign); (3) Q waves > 0.03 second in duration in leads I, aVL, or V6; (4) Notching of the first 0.04 second of the QRS complex in leads II, III, and aVF; (5) Q wave > 0.03 second in duration in leads II, III, and aVF. The most sensitive criteria, for anterior and inferior myocardial infarctions were Cabreras and Chapmans (91.1 and 86.6%, respectively). All criteria had low specificity (range 42.3–69.2%). The combination of Cabreras and Chapmans sign decreased the sensitivity to 77.7%, but increased specificity to 82.2%. The sensitivity and specificity of all the criteria were independent of the myocardial infarction site. In paced patients, the application of electrocardiographic criteria, and especially the combination of Cabrera and Chapman, provides useful clinical information in recognizing prior myocardial infarction but not in assigning the specific infarct site.

Complications Related to Cardiac Rhythm Management Device Therapy and Their Financial Implication: A Prospective Single-Center Two-Year Survey

INTRODUCTION Cardiac rhythm management devices (CRMDs) have proven their clinical effectiveness for patients with heart rhythm disorders. Little is known about safety and complication rates during the implantation of these devices. This study demonstrated the complication rates related to CRMD implantation, and estimated the additional hospital stay and cost associated with the management of complications. METHODS During a period of one year, a total of 464 consecutive recipients underwent CRMD implantation and were followed for 2 years. Finally, data were analyzed for 398 patients who completed the two-year follow up, resulting in a total of 796 patient-years. RESULTS Of the 201 patients with initial pacemaker (PM) implantations, 6 (2.99%) had seven complications (5 patients had lead dislodgement, 1 of them twice), and 1 patient developed pocket infection. Of the 117 PM replacements, 1 (0.85%) patient developed a complication (pocket erosion). Two patients with complications (1 with an initial PM and 1 with a replacement) died before completing the follow up for reasons unrelated to cardiac causes. There were no complications in either initial implantations (69 patients) or replacements (11 patients) of implantable cardioverter-defibrillators. The average prolongation of the hospital stay was 7 days, ranging from 1 to 35 days, resulting in 17,411 of total additional direct hospital costs. CONCLUSION This study found relatively low rates of complications in patients undergoing CRMD implantation, initial or replacement, in our center, compared with other studies. The additional hospitalization days and costs attributable to these complications depend on the nature of the complication.