n.9 – I123-MIBG PROGNOSTIC VALUE IN A SELECTED PATIENTS POPULATION WITH IDIOPATHIC CARDIOMYOPATHY CANDIDATE TO AICD IMPLANT: UPDATE OF A PILOT STUDY



Abstract

BACKGROUND-AIM
Chronic heart failure is characterized by an high percentage of arrhythmic cardiac sudden death. Currently doesn’t exist a reliable screening test to select effectively patients candidate to the AICD implant. Guidelines recommend AICD implant to the patients with an optimal medical therapy, EF persistently <35%, functional NYHA class II-III and at least 1 year of life expectancy. An high percent among them will never utilize the device or it will operate in a inappropriate manner with increased costs.
The MIBG scintigraphy demonstrated to be useful about prognostic stratification ability among Patients with an high arrhythmic risk. More trials have always enrolled patients with extremely heterogeneous features, mixing patients’ data both with CAD and idiopathic CMP.
METHODS
Our pilot study has selected an homogeneous group of 32 patients with idiopathic dilatative cardiomyopathy (EF<35% in optimal medical therapy at least from 3 months). Diagnostic angiography excluded in all of them coronary disease. They were all candidates to the AICD implant. We have studied cardiac innervation after MIBG scintigraphy through the Heart/Mediastinum late rate, the wash-out rate background and evaluating a possible correlation with the left ventricular diameter and the left atrium sizes. The aim of our study is to verify if these collected data could be connected with arrhythmic events which had request the AICD intervention and to identify a cut-off in H/M late and wash-out rate.
RESULTS
We have highlighted a medium H/M rate late about 1.62 (range 1.27-2.1), a medium wash-out rate background corrected 34.6 (range 16.64-59.26). During pre-programmed AICD control after a 28 months follow-up, we have observed 3 ventricular fibrillation episodes treated with shock and 1 sustained ventricular tachycardia resolved by overdrive stimulation (ATP).In remaining cases, the device doesn’t reported arrhythmic events and/or worsening of clinical conditions. Ventricular sizes seem to have a good proportional correlation with the H/M late rate and with the cardiac events. This correlation isn’t so reliable with the atrium sizes.
Patients with arrhythmic events showed a late H/M late ratio respectively around 1.48, 1.31, 1.35 and 1.23; a ventricular diameter around 70 mm and a wash-out rate bkg corrected respectively of 32.27, 40.15, 47.8, 38.2. Other 28 patients with a regular clinical course showed an H/M late ratio >1.4 (mean 1.76, range 1.43-2.10) and ventricular diameters <65mm.
Subdividing Patients with ADMIRE cut-off (H/M late 1.6), we observed no events in Patients group with H/M late >1.6, while 4 arrhythmic events occurred in Patients with H/M late <1.6.
CONCLUSION
Our experience seems to endorse the prognostic validity of this method and it’s comparable with ADMIRE study data where an H/M late >1.6 identify a group of patients with a low risk of arrhythmic events. In these patients it should be possible procrastinate AICD implant while an H/M late <1.6 should identify a group with an high arrhythmic risk and the AICD implant is soon indicated.

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