Cardiac resynchronization therapy is an essential tool for treating patients with heart failure in different types of dilatative cardiomyopathy with bundle branch block. This technique is wildly used with significant benefits in terms of quality of life and effort tolerability along with optimized medical therapy. In spite of its benefits, several factors may influence its efficacy such as etiology, lead position, or device settings. In some cases, the anatomical variance of the coronary sinus could create technical difficulties for advancing the left ventricular lead. This case report describes a female patient presenting with decompensated heart failure, known with complicated sclerosis multiplex and a fibrous tissue in the coronary sinus, which created a critical obstruction leading to impossibility to advance the left ventricular lead. This case underlines the importance of appropriate imaging investigation for optimal interventional approach in these difficult cases.