We implanted a Cardiac Contractility Modulation (CCM) device in a 66-year-old man with congestive acute heart failure (AHF) refractory to optimized medical therapy and non-responder to CRT-D since 2015. The patient was evaluated multiple times and declared ineligible for a new heart by several heart transplant centers. Effective periodic Levosimendan treatments were performed before the implantation.. However hospitalizations still occurred monthly. The Echo exam, on the day of the implant, showed a left ventricular ejection (LVEF) fraction of 25%, PAPS of 30 mmHg, and E/E’ of 26. Interrogation of the CRT-D revealed an AF burden of 35% and several episodes of tachyarrhythmia at high frequency (130 bpm). The benefits of CCM therapy were almost immediate with the disappearance of breathlessness and the absence of hospitalizations for seven months. Only in June 2022, the patient was admitted to the ER for HF symptoms. At the admission, the heart rate was 125 bpm and, by performing the follow-up of the CCM device, the percentage of delivered therapy was low (<20%) due to the high heart rate. The interrogation of the ICD showed a reduced AF Burden (19 %). However, in the two weeks before the admission, several episodes of organized supraventricular tachycardia (SVT) conducted 1:1, at a rate of around 140 bpm, were recorded and stopped the CCM the device from delivering any impulse, in the absolute refractory period. In the HF Diagnostics implemented in the ICD, we also noticed an indication of fluid overload consistent with a steep reduction of intrathoracic impedance in the exact same time frame. Consequently, we increased the dosage of BB to reduce the heart rate and allow CCM delivery to reach a percentage higher than 80% within the 24 hours timespan. The clinical status of the patient improved immediately in the next following days. The HF diagnostics of ICD, after three weeks from discharge, revealed an increase in intrathoracic impedance and a decrease in hypervolemia which were consistent with the improved symptoms reported by the patient. Finally, the echocardiographic exam at 6 months from the implant showed an EF of 32, PAPS of 30 mmHg, and E/E’ of 12 which justified a decrease in the score of the Minnesota Living with Heart Failure Questionnaire (MLWHF) from 80 (before CCM) to 36 after the implantation. A multiparametric evaluation of CCM delivery must be performed during the patient's follow-up to maximize the efficacy of the therapy itself.