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This study evaluated a possible placebo effect by pacemaker implantation. The study design was a 3-month multicenter, double-blind, randomized cross-over study to compare the effects of atrioventricular (AV) synchronous pacing with an optimal AV delay to inactive pacing in patients with obstructive hypertrophic cardiomyopathy (HC). Quality of life and left ventricular (LV) outflow tract obstruction were evaluated after the first study period in 40 patients assigned to inactive pacing. Data were compared with the corresponding results among the 41 subjects assigned to a first study period of active pacing. During inactive pacing, there was a significant improvement in perceived chest pain, dyspnea, and palpitations. Moreover, LV outflow tract gradient decreased from 71 +/- 32 mm Hg to 52 +/- 34 mm Hg (p = 0.04). In patients assigned to active pacing the reduction of the gradient was significantly more pronounced (70 +/- 24 mm Hg to 33 +/- 27 mm Hg; p <0.0001). The difference in gradient reduction between the groups was highly significant (p <0.00001). In the group assigned to active pacing there was also significant improvement in perceived symptoms as well as in alertness, the ability to be self-autonomous, and strenuous physical exercise. The improvements in the latter were significantly greater in those paced actively compared with patients paced inactively, whereas the changes in perceived symptoms did not differ between groups. In conclusion, pacemaker implantation had a placebo effect on objective and subjective parameters in this group of patients with obstructive HC. [ABSTRACT FROM AUTHOR]

Atrioventricular (AV) synchronous pacing reduces left ventricular (LV) outflow tract obstruction and symptoms in patients with obstructive hypertrophic cardiomyopathy (HC). The duration of gradient reduction, if pacing is discontinued for a prolonged period of time, is unknown. This question is addressed in the present randomized double-blind crossover study comparing continued with inactivated pacing. Ten patients, successfully paced for > or = 6 months, were randomized to continue pacing or to have their pacemakers inactivated after baseline examinations, including echo-Doppler imaging, exercise testing, and a quality-of-life questionnaire. When entering the study, the patients were in New York Heart Association functional classes I to II. After pacemaker programming, examinations were repeated at 1, 4, and 12 weeks. At the 12-week follow-up the alternate pacing mode was programmed, and the patient entered the second study arm. Premature pacemaker pacing occurred if severe clinical deterioration or a significant increase of the LV outflow tract obstruction were evident. Three patients started in the inactive mode and 7 patients in the active mode. All patients who started with the pacemaker inactivated required early reprogramming due to return of symptoms after 7, 10, and 13 days, respectively. All 7 patients who started in the active pacing mode completed the first period; however, after reprogramming to the inactive mode they required early activation after 1 to 20 days due to reappearance of intolerable subjective symptoms. The LV outflow tract gradient increased significantly after inactivation of pacing in all patients (22 +/- 21 mm Hg to 47 +/- 21 mm Hg). Thus, AV synchronous pacing effectively relieves symptoms and reduces the LV outflow tract gradient in patients with obstructive HC. This improvement, which is rapidly established with the initiation of cardiac pacing, is not persistent after cessation of pacing. Reinitialization of pacing promptly reduces the LV outflow tract obstruction and relieves symptoms to a preexisting extent. [ABSTRACT FROM AUTHOR]

To assess the impact of biventricular pacing on quality of life over 12 months of follow-up, 76 patients in the MUSTIC trial were evaluated by 2 instruments: The Minnesota Living with Heart Failure Questionnaire and the Karolinska Quality of Life Questionnaire. MUSTIC is a randomized, controlled study to evaluate the effects of biventricular pacing in patients in New York Heart Association class III heart failure with intraventricular conduction delay. Following a single, blind, crossover comparison of 3 months of biventricular pacing to inactive pacing (sinus rhythm group) or ventricular-inhibited pacing (atrial fibrillation group), 85% of patients preferred and were programmed to biventricular pacing and were followed for 12 months. In parallel with clinical improvements, substantial benefits in quality of life for most broad domains of quality of life and cardiovascular symptoms were found during biventricular pacing already within the crossover phase with a maintained benefit over the 12-month follow-up. Biventricular pacing improved quality of life in patients with heart failure and intraventricular conduction delays. The benefits were sustained over 12 months of follow-up. [Copyright &y& Elsevier]

Cardiac resynchronization therapy (CRT) can improve global left ventricular (LV) function. However, limited data are available on regional LV contractility at rest and during exercise. The aim of the present study was to prospectively investigate the effects of CRT on regional LV ejection fraction (EF), global LVEF, and dyssynchrony, during rest and exercise, using radionuclide angiography. A total of 32 consecutive patients with heart failure and nonischemic cardiomyopathy underwent technetium-99m radionuclide angiography with bicycle exercise immediately after CRT implantation (during spontaneous rhythm and after CRT activation) and 3 months later. The regional EF was assessed in the interventricular septum and the lateral wall (LW). Intraventricular dyssynchrony was evaluated using Fourier phase analysis. During spontaneous rhythm, the EF was severely depressed in the septum compared to in the LW. CRT improved septal EF at rest and during exercise both at baseline (p <0.001) and after 3 months (p <0.05). The basal LW EF decreased during CRT (p <0.05, both at rest and during exercise). LV dyssynchrony decreased both at baseline and during follow-up, and the global LVEF showed improvement only at 3 months (p <0.001). In conclusion, in patients with nonischemic cardiomyopathy, CRT affects regional LV function by increasing the septal EF and reducing LW contractility, both at rest and during exercise. This was associated with an improvement in global LVEF and dyssynchrony. [Copyright &y& Elsevier]

To assess the impact of biventricular pacing on quality of life over 12 months of follow-up, 76 patients in the MUSTIC trial were evaluated by 2 instruments: The Minnesota Living with Heart Failure Questionnaire and the Karolinska Quality of Life Questionnaire. MUSTIC is a randomized, controlled study to evaluate the effects of biventricular pacing in patients in New York Heart Association class III heart failure with intraventricular conduction delay. Following a single, blind, crossover comparison of 3 months of biventricular pacing to inactive pacing (sinus rhythm group) or ventricular-inhibited pacing (atrial fibrillation group), 85% of patients preferred and were programmed to biventricular pacing and were followed for 12 months. In parallel with clinical improvements, substantial benefits in quality of life for most broad domains of quality of life and cardiovascular symptoms were found during biventricular pacing already within the crossover phase with a maintained benefit over the 12-month follow-up. Biventricular pacing improved quality of life in patients with heart failure and intraventricular conduction delays. The benefits were sustained over 12 months of follow-up. [ABSTRACT FROM AUTHOR]