Does reducing unnecessary right ventricular pacing improve sympathetic activity and innervation of heart in sinus node disease patients? MVP and SafeR study.

Ventricular desynchronization imposed by ventricular pacing causes regional disturbances of adrenergic innervation in the left ventricular myocardium and increases the risk of heart failure and atrial fibrillation (AF) in patients with sinus node disease (SND). As a result, decreased iodine-123 metaiodobenzylguanidine (I-(123 )MIBG) uptake occurs in patients with an implanted permanent pacemaker. Fourteen SND patients with an implanted pacemaker equipped with an algorithm for reducing unnecessary right ventricular pacing (RURVP) were enrolled. Pacemakers were programmed to RURVP mode for the first 12 weeks, and then reprogrammed to DDD for the last 12 weeks. At the end of each mode, data on cumulative percent ventricular pacing (%Vp), atrial high rate episodes (%AHR), I-(123 )MIBG myocardial scintigraphy, brain natriuretic peptide (BNP), human atrial natriuretic peptide (hANP), and myocardial damage indices typified by troponin T and C-reactive protein (CRP) were collected. %Vp was lower in RURVP than in DDD (0.2% versus 95.7%, P = 0.00098). BNP, hANP, troponin T, and CRP did not differ significantly between the pacing modes. However, I-(123 )MIBG findings of patients with full ventricular pacing in DDD improved in RURVP. In contrast, among patients without full ventricular pacing in DDD, their I-(123 )MIBG findings did not differ significantly between the pacing modes. In SND patients with normal cardiac function and intact atrioventricular conduction, the reduction of %Vp in RURVP was due to the reduction of ineffective pacing and fusion pacing in DDD. Therefore, these 2 types of pacing do not affect cardiac pump function.

Impact of renal insufficiency on long-term clinical outcome in patients with heart failure treated by cardiac resynchronization therapy.

BACKGROUND: Renal insufficiency is recognized as a predictor of mortality and adverse outcome in heart failure (HF) patients. However, the long-term clinical outcome of cardiac resynchronization therapy (CRT) in Japanese HF patients with renal insufficiency remains uncertain. METHODS: We evaluated 67 consecutive patients who underwent CRT at our hospital. The patients were divided into two groups according to a baseline estimated glomerular filtration rate (e-GFR) cut-off value of 50ml/min, which is defined as the time at which patients should be referred to a nephrologist, by the Japanese Society of Nephrology. Follow-up echocardiographic findings and renal function were examined at 3-6 months after CRT. Then, we compared long-term clinical outcomes between the two groups, and analyzed the effect of CRT on renal function, echocardiographic parameters and cardiac survival. RESULTS: During a mean follow-up period of 30.3 months, patients with advanced renal insufficiency (e-GFR<50ml/min) had significant higher all-cause mortality (log-rank p=0.033) and higher cardiac mortality combined with HF hospitalization (log-rank p=0.017) than patients with e-GFR≥50ml/min. Multivariate analysis revealed that advanced renal insufficiency was an independent predictor of cardiac mortality combined with HF hospitalization (odds ratio=3.01, p=0.008). Subgroup analysis in the baseline advanced renal insufficiency group revealed that patients with preserved renal function by CRT (<10% reduction in e-GFR) had a higher rate of decrease of left ventricular end-systolic diameter (-14.0% vs. -0.8%, p=0.023) and lower cardiac mortality combined with HF hospitalization (log-rank p=0.029) compared with patients with deterioration of renal function (≥10% reduction in e-GFR). CONCLUSIONS: The present study suggests that advanced renal insufficiency is quite useful for the prediction of worsening clinical outcomes in HF patients treated by CRT. Preservation of renal function by CRT brings about better cardiac survival through prevention of adverse cardiac events, even in HF patients with advanced renal insufficiency.