Freddy M. Abi-Samra

Determinants of left ventricular hypertrophy and function in hypertensive patients: An echocardiographic study

Hypertensive patients present a wide spectrum of echocardiographic alterations. A review of these changes in 74 patients (37 untreated and 37 treated) revealed left ventricular hypertrophy in 43 (58 percent). There was no significant difference between treated and untreated patients in regard to either the prevalence of left ventricular hypertrophy or of its various subtypes [concentric left ventricular hypertrophy in 15 (20.3 percent), asymmetric septal hypertrophy in 16 (21.6 percent), and combined left ventricular hypertrophy and dilation in 12 (16.2 percent)]. None of the patients who showed asymmetric septal hypertrophy had abnormal motion of the mitral valve. Cardiac performance as judged by left ventricular percent shortening was related inversely to end-systolic stress (p less than 0.001) and positively to the ratio of end-systolic pressure/end-systolic volume (an index of myocardial contractility) (p less than 0.01). Multiple regression analysis showed an increased dependence on afterload (end-systolic stress), when left ventricular hypertrophy developed and especially when it was associated with left ventricular dilation.

Clinical variables affecting recovery of left atrial mechanical function after cardioversion from atrial fibrillation

OBJECTIVES We sought to evaluate the effect of clinical factors on recovery of atrial function after cardioversion for atrial fibrillation. BACKGROUND Lack of effective mechanical atrial function (EMAF) after cardioversion of atrial fibrillation predisposes to thromboembolic complications and delays improvement in functional capacity. METHODS Fifty-two patients underwent cardioversion (group I, electrical cardioversion, n = 40; group II, pharmacologic or spontaneous cardioversion, n = 12) for atrial fibrillation. Serial transmitral inflow Doppler variables were recorded after cardioversion until EMAF (atrial filling velocity > 0.50 m/s) was seen. Clinical variables (age, duration of atrial fibrillation, left ventricular ejection fraction, left atrial diameter, underlying cardiovascular disease, antiarrhythmic drug therapy and mode of cardioversion) were tested for an association with the outcomes of recovery of atrial function by day 3 and day 7. RESULTS Effective mechanical atrial function recovered in 68% of patients by day 3 and in 76% by day 7 after cardioversion. The mode of cardioversion was significantly associated with recovery of atrial function by day 3 in bivariate and multivariate analyses (odds ratio 0.12, 95% confidence interval 0.01 to 1.0, for electrical cardioversion). None of the variables had an association with recovery of atrial function by day 7. Group I patients took a longer time to recover atrial function than group II patients (p = 0.012). In addition, group I patients had a significantly lower peak atrial filling velocity (mean [+/-SD] 0.39 +/- 0.19 m/s vs. 0.56 +/- 0.16 m/s) and a higher early filling to atrial filling velocity ratio (2.5 +/- 1.2 vs. 1.5 +/- 0.5) after cardioversion. CONCLUSIONS A high proportion of patients recover EMAF within 1 week after cardioversion. Patients who undergo electrical cardioversion display a greater degree and a longer duration of mechanical atrial dysfunction than those who convert pharmacologically or spontaneously.

Mechanical dysfunction of the left atrium and the left atrial appendage following cardioversion of atrial fibrillation and its relation to total electrical energy used for cardioversion

In 39 patients undergoing electrical cardioversion for atrial fibrillation (AF), we examined the effect of total electrical energy used for cardioversion on postcardioversion peak left atrial (LA) rapid filling velocity (A) and the atrial emptying fraction, and recovery of LA effective mechanical atrial function (defined as peak A velocity > or = 0.50 m/s), as assessed by transthoracic echocardiography. In a subset of 27 patients who underwent pre- and postcardioversion transesophageal echocardiography, we assessed the relation between total electrical energy and LA appendage filling and emptying velocities and spontaneous echo contrast. Patients were randomized to receive an initial shock of 1.5 J/kg based on body weight, or 2.5, 3.5, 5 J/kg, or 360 J, followed sequentially by higher shock intensities until sinus rhythm was achieved. Patients were classified into 4 groups based on quartiles of total energy delivered for cardioversion. Conversion to sinus rhythm was associated with a significant decrease in the LA appendage filling velocities (0.42 +/- 0.20 m/s vs 0.29 +/- 0.14 m/s; p = 0.002) and LA appendage emptying velocities (0.40 +/- 0.22 m/s vs 0.29 +/- 0.18 m/s; p = 0.03), but no change in the incidence of spontaneous echo contrast (61% vs 70%, p = 0.08). The 4 groups of patients did not differ with respect to postcardioversion LA appendage filling velocities, LA appendage emptying velocities, incidence of spontaneous echo contrast, or worsening of spontaneous echo contrast. Similarly, the change in LA appendage filling and emptying velocities associated with cardioversion was not different between the groups. Furthermore, postcardioversion peak A velocity and atrial emptying fraction and recovery of effective mechanical atrial function were similar between the 4 groups. These results suggest that in patients undergoing electrical cardioversion for AF, the total electrical energy used for cardioversion has no effect on the mechanical function of the left atrium or LA appendage following cardioversion.

Relationships between the T-peak to T-end interval, ventricular tachyarrhythmia, and death in left ventricular systolic dysfunction

AIMS The interval between the T-waves peak and end (Tpe), an electrocardiographic (ECG) index of ventricular repolarization, has been proposed as an indicator of arrhythmic risk. We aimed to clarify the clinical usefulness of Tpe for risk stratification. METHODS AND RESULTS We evaluated 327 patients with left ventricular ejection fraction (LVEF) ≤ 35% (75% male, LVEF 23 ± 7%). All patients had an implanted implantable cardioverter-defibrillator (ICD). Clinical data and ECGs were analysed at baseline. Prospective follow-up for the endpoints of appropriate ICD therapy and mortality was conducted via periodic device interrogation, chart review, and the Social Security Death Index. During device clinic follow-up of 17 ± 12 months, 59 (18%) patients had appropriate ICD therapy, and during mortality follow-up of 30 ± 13 months, 67 (21%) patients died. A longer Tpe(c) predicted appropriate ICD therapy, death, and the combination of appropriate ICD therapy or death (P< 0.01 for each endpoint). On multivariable analysis correcting for other univariable predictors, Tpe(c) remained predictive of ICD therapy [hazard ratio (HR) per 10 ms increase: 1.16, P= 0.02], all-cause mortality (HR per 10 ms: 1.14, P= 0.03), and the composite endpoint of ICD therapy or death (HR per 10 ms: 1.16, P< 0.01). CONCLUSIONS In patients with left ventricular systolic dysfunction and an implanted ICD, Tpe(c) independently predicts both ventricular tachyarrhythmia and overall mortality.

Lifestyle modification in the prevention and treatment of atrial fibrillation.

Atrial fibrillation (AF) is the most common arrhythmia worldwide and has a significant impact on morbidity and mortality. Additionally, the incidence and prevalence of AF is expected to increase in the United States and worldwide over the next few decades. While the pathophysiology concerning the development of AF is not completely understood, multiple modifiable, as well as non-modifiable risk factors, for AF development have been discovered. The goal of this paper is to provide an overview of the modifiable risk factors that contribute to the development and recurrence of AF, in addition to discussing potential lifestyle changes that may aid in the prevention and treatment of AF.

The signal-averaged electrocardiogram in cardiac transplantation: A noninvasive marker of acute allograft rejection

Cardiac allograft rejection represents a major cause of morbidity and mortality in transplanted patients. Noninvasive markers of rejection have been sought, though transvenous endomyocardial biopsy remains the “gold standard” for the diagnosis of rejection. Sixty-one signal-averaged electrocardiograms (five in patients with rejection and 56 in patients without rejection) were obtained on 41 patients and prospectively analyzed in frequency domain via fast Fourier transform (FFT). Patients with acute allograft rejection demonstrate a significant increase in the high-frequency components of the QRS complex upon FFT analysis (QRS area ratio 203±S7 vs. 66±10, P=0.0007) compared with patients without rejection. Thus, frequency domain analysis may be a useful noninvasive marker of acute cardiac allograft rejection.

Repeated dual external direct cardioversions using two simultaneous 360-J shocks for refractory atrial fibrillation are safe and effective.

Failure of cardioversion of atrial fibrillation (AF) to sinus rhythm (SR) by standard external direct current cardioversion (DCC) may be due to failure of delivery of enough defibrillating energy rather than to the true refractoriness of AF. Ninety‐nine patients with persistent AF (76 male; age 63.7 ± 0.4 years; weight 113.1 ± 25.1 kg) who failed standard DCC were included in this report. Under anesthesia, QRS synchronous shocks were delivered across anteroposterior electrodes in the following sequence: (1) a single 360‐J shock; (2) another single 360‐J shock within 2 minutes; (3) 30 minutes of rest, reinduction of anesthesia and delivery of two simultaneous monophasic 360‐J shocks. All patients underwent all three DCC steps. Sixty‐six (67%) patients converted to SR following the first dual simultaneous shock. Fourteen patients (14%) required more than one dual shock to achieve SR. This increased the overall success rate of resuming SR to 81%. Except for minor skin burns in three patients there were no procedure related complications. On follow‐up at 1 month, 55 (56%) patients were still in SR, whereas 50 (51%) patients maintained SR at 12 months. This was similar to our general DCC population (55% of the 1698 patients were in SR 6 months post‐DCC, P = ns). In conclusion, dual external monophasic 360‐J DCC is an effective rescue technique for restoration of SR in patients with AF refractory to standard DCC. AF in these patients seems to be as amenable to chronic suppression as AF in the general population of DCC patients.

Effect of rate-adaptive pacing on performance and physiological parameters during activities of daily living in the elderly: results from the CLEAR (Cylos Responds with Physiologic Rate Changes during Daily Activities) study

Aims For most elderly pacemaker patients, evaluation of rate-adaptive pacing using treadmill and bicycle tests is impractical and not representative of typical daily activities. This study was designed to compare the performance and physiological response of the closed-loop stimulation (CLS) rate-adaptive sensor to accelerometer (XL) and no rate sensor (DDD) during typical daily activity testing. Methods and results Subjects recently implanted with a Cylos pacemaker completed timed activities of daily life testing, which included walking, sweeping, and standing from a seated position. Activity performance and physiological response from each sensor mode was evaluated for subjects requiring ≥80% pacing. Overall, 74 subjects needed ≥80% pacing during at least one test. An increase in the area swept (CLS vs. XL, 1.67 m2 difference, P = 0.009; CLS vs. DDD, 1.59 m2 difference, P = 0.025) and a decrease in the prevalence of orthostatic hypotension (OH) after standing 1 min (CLS vs. XL, odds ratio = 0.16, P = 0.006; CLS vs. DDD, odds ratio = 0.18, P = 0.012) was observed in the CLS mode as compared with XL and DDD. No statistical difference in walk distance was observed between CLS and XL or CLS and DDD. Conclusion In acute testing, as compared with XL and DDD, CLS provides a more physiological response during the performance of activities of daily living for subjects with ≥80% pacing. This is clinically reflected in better performance during the sweep test as well as a decrease in the prevalence of OH in our elderly population. Clinicaltrials.gov identifier: NCT00355797

Long‐Term Mortality in Patients with Pauses in Ventricular Electrical Activity

Background: The long‐term significance of ventricular pauses of ≥3.0 seconds observed on Holter monitor is unclear, as previously conducted retrospective studies have been poorly controlled. We compared the prognosis of patients with pauses ≥3.0 seconds on Holter monitor with a well‐matched control group without such pauses.

CORRELATION BETWEEN POSITRON EMISSION TOMOGRAPHY STRESS MYOCARDIAL BLOOD FLOW AND VENTRICULAR TACHYARRHYTHMIA OR DEATH IN PATIENTS WITH CARDIOMYOPATHY

In patients with cardiomyopathy (CM) and an implantable cardioverter-defibrillator (ICD), the relationship between positron emission tomography (PET) stress myocardial blood flow (sMBF) and adverse cardiac events including ventricular arrhythmia (VT/VF) is unknown. Patients with CM with an ICD in